Vitamin A deficiency is common among preschoolers in low-income settings and a serious public health concern due to its association to increased morbidity and mortality. The limited consumption of vitamin A-rich food is contributing to the problem. Many factors may influence children’s diet, including residential food environment, household wealth, and maternal education. However, very few studies in low-income settings have examined the relationship of these factors to children’s diet together. This study aimed to assess the importance of residential food availability of three plant-based groups of vitamin A-rich foods, household wealth, and maternal education for preschoolers’ consumption of plant-based vitamin A-rich foods in Addis Ababa. A multistage sampling procedure was used to enroll 5467 households with under-five children and 233 residential food environments with 2568 vendors. Data were analyzed using a multilevel binary logistic regression model. Overall, 36%  of the study children reportedly consumed at least one plant-based vitamin A-rich food group in the 24-h dietary recall period. The odds of consuming any plant-based vitamin A-rich food were significantly higher among children whose mothers had a higher education level , those living in the highest wealth quintile households , and in residentials where vitamin A-rich fruits were available . Further research in residential food environment is necessary to understand the purchasing habits, affordability, and desirability of plant-based vitamin A-rich foods to widen strategic options to improve its consumption among preschoolers in low-income and low-education communities. Vitamin A deficiency (VAD) is a serious public health problem and one of the nutritional challenges faced by children in low-income countries, especially among those from the poorest communities . Pre-schAlthough vitamin A supplementation (VAS) has been implemented via routine child health programs in an effort to address VAD in Ethiopia ,10,11, sThe food environment is increasingly recognized to play significant role in shaping the diet of the children and their families globally . A food A systematic review of evidence in low-and middle-income countries has shown the influence of household socio-economic status on fruit and vegetable intake . A recenUnderstanding the importance of food availability for preschoolers’ diet and comparing its significance with that of commonly addressed socio-economic characteristics can contribute with a more in-depth understanding of the factors which need to be addressed to promote healthy dietary habits.This study aims to examine the consumption level of plant-based vitamin A-rich foods among children under the age of five, and to assess to what extent the residential availability of vitamin A-rich plant-based foods, household wealth, and maternal education influence the consumption of these foods by children aged 6 to 59 months in Addis Ababa.Addis Ababa is the largest city in Ethiopia, and one of the fastest-growing cities in the African continent , with anAt the time of data collection, Addis Ababa was administratively divided into 10 sub-cities and 117 woredas , with each sub-city comprising of 10–15 woredas.This study utilizes data collected in the EAT Addis survey which collected data from households and vendors in residential areas in all woredas of Addis Ababa. Data collection was conducted in two rounds to account for seasonality, capturing July to August 2017, reflecting a wet season, and January to February 2018, reflecting the post-harvest period.We used a multistage sampling procedure. Each of the 117 woredas in Addis Ababa were included in the survey. Each woreda was divided into five clusters to simulate the enumeration procedure in the Ethiopian Demographic and Health Surveys . One cluTo identify eligible households with children under five years of age in the cluster, we used a systematic random sampling procedure visiting every third household from a random starting position until we reached a total of 60 households per cluster. These households were assessed for eligibility based on presence of at least one child under five years of age. In cases where an eligible household had more than one eligible child, one child was randomly selected to be the index child from whom dietary data was to be collected. The mother or caretaker of the index child was invited to participate in the survey and was also the main respondent at the household data collection. Mothers or caregivers not at home following three recruitment visits were declared unavailable. For the purpose of this study, household with children age below six months were not included.To identify a residential food environment representing the cluster, one household per cluster was randomly selected to serve as an index household, around which all vendors within a five-minute walk in all direction were surveyed. In total, 14 type of vendors such as kiosk, micro vendor, bakery, fruit/vegetable shop, four mill, butcher, cooperative shop, ET-Fruit, street food vendor, mini market, dairy shop, mobile micro-vendor, livestock market, and fish market were included in the survey. Vendors which were not open at the time of the visit were declared unavailable.Instruments were developed to collect data from households and vendors. These instruments were drafted in English and subsequently translated into Amharic. All data collectors and supervisors had extensive previous field research experience and received training on the data collection tools, interview procedures, and ethical conduct pertaining to the study . Pilot tAn overall aim in the EAT Addis survey was to evaluate the association between food availability in residential food environments and food consumption of the household and pre-school children. To facilitate comparison, we developed a common metric to assess food availability and food consumption. A frequently used type of indicator is diet diversity, and indicators have been developed for use in different population groups including children ,37,38. WThe household survey featured data collection on a number of aspects, but of relevance for this study is mainly infant and young child feeding, household wealth, maternal education, and distance between households and index household.Children aged 6–59 months were included in this study. The caregiver of the index child was asked to recall the child’s food consumption during 24 h recall period. In addition to the initial recall by the caretaker a photo gallery of locally available items was used to augment the listing of food groups to ensure a common understanding among our enumerators and participants. For the purpose of this study, three photos with common items representative of the food groups were used: vitamin A-rich vegetables , vitamin A-rich fruits , and dark green leafy vegetables . Consumption was categorized as yes or no to each of the three food groups.The household wealth index was developed by principal component analysis and categorized into wealth quintiles . This waDistance between households and index household were calculated based on geographical positioning system (GPS coordinates) of each household during the data collection. The Euclidian distance was calculated based on the geographical location points (latitude/longitude) using a trigonometric approach (distance formula) .A survey of all food vendors within a five-minute walking radius from the index household was conducted. The data collection tool for the residential food environment survey consists of the vendor characteristics, vendor properties, and food availability. The survey tool was pilot tested in three randomly selected residential food environments to assess the feasibility and the relevance of the terminology and typologies. The same food groups and photo gallery of locally available food items used in the household survey was also used in the survey of vendors in the residential area. Of relevance for this study, each vendor was categorized as selling or not selling any items from each of the three vitamin A food rich food groups, such as vitamin A-rich fruits, dark green leafy vegetables, and vitamin A-rich vegetables and roots. For each food group, the residential availability was defined as the presence of at least one vendor in the area selling any item from that particular group .We used STATA 14 software for data analysis. Frequencies and percentages were calculated to report descriptive statistics. The predictor of plant-based vitamin A-rich food consumption was assessed using a multilevel binary logistic regression analysis with meaningful nested hierarchy at household and residential food environment level . The intThis study was approved by the Ethical Review Board of Addis Continental Institute of Public Health (Ref No. ACIPH/IRB/004/2015), and the Ethical Review Board at University of Gondar (R.No.-V/P/RCS/05/355/2019). No identifying information was available for this study.A total of 14,018 households were visited, leading to the identification of 5467 eligible and consenting households. Among eligible households, 4911 children were in the age group 6 to 59 months and were eligible for inclusion in this study, while the remaining 556 children were under 6 month of age and therefore ineligible for this study, as exclusive breast feeding is recommended in this age group A. In theMale and female children were almost equally represented in the sample in all age groups. The mean (±SD) age of the children was 28.4 (±0.2) months. The majority (88%) of the children’s mothers were married. Approximately two-thirds (74%) of the mothers reported no income-earning activities. Approximately one-fifth of the mothers (19%) had a college education, an access of private toilet (23%), and lived in their own house (22%) Consumption of plant-based vitamin A-rich food was limited, with only 36% of the children having consumed at least one type of vitamin A-rich food in the previous 24 h. The highest consumed vitamin A-rich food item was vitamin A-rich vegetables and roots (20%), followed by dark green leafy vegetables (17%) and vitamin A-rich fruits (9%). Only 9% of the children had consumed more than one type of plant-based vitamin A-rich foods in the previous 24 h.The majority (78%) of residential food environments had at least one of the plant-based vitamin A-rich food available. The residential availability of vitamin A-rich fruits was low (36%), as compared with the other two vitamin A-rich food items . The mosp-value = 0.03). Similarly, children residing in residential food environments where vitamin A-rich fruits were available had significantly higher consumption of vitamin A-rich rich plant source foods (39%), compared to those residing in residential food environments where these foods were not available . The difference in the children’s consumption of vitamin A-rich plant source food between children from residentials with and without the availability of vitamin A-rich vegetables and roots, and dark green leafy vegetables was small , compared to those residing in residential food environments where these foods were not available (34%) . A similar pattern was observed in relation to maternal education: children whose mothers had college level education had a significantly higher consumption of at least one vitamin A-rich plant source food (48%) than children with lower maternal education (23%) . The consumption pattern showed a marked improvement as the wealth status of the household improves and maternal education status increases  than children from the lowest wealth quintile (25%) (ncreases .In the full model (Model III), the odds of consuming plant-based vitamin A-rich food was 19% higher among children residing in residential food environments with vitamin A-rich fruits available, compared to those residing in residential food environments without this food type available . However, the strength of this positive association was relatively weak when compared to the individual level influences on child consumption.Children’s consumption of vitamin A-rich food increased progressively with maternal education and household wealth. The odds of consuming plant-based vitamin A-rich food were 2.55 times higher for children whose mothers were college-educated, compared to those children whose mothers had no education . Similarly, the odds of consuming plant-based vitamin A-rich food were 2.37 times higher for children from households in the highest wealth quintile compared to children from households in the lowest quintile  . The assThe results of this study showed that only 36% of children had consumed plant-based vitamin A-rich food groups in the last 24 h during the survey. While residential availability of vitamin A-rich vegetables, roots, and dark green leafy vegetables had no association, the availability of vitamin A-rich fruits had a weak positive association with the children’s consumption of plant-based vitamin A-rich food. Higher household wealth and maternal educational status showed strong association with the consumption of plant-based vitamin A-rich food.We found the overall consumption of plant-based vitamin A-rich food to be low among children in Addis Ababa. In particular, the intake of vitamin A-rich fruit among children was low (<10% of the children) compared to vitamin A-rich vegetables and roots and dark green leafy vegetables, as reported by previous research. This finding supports several existing studies in Ethiopia that also supported low intake of vitamin A-rich foods; for example, a study in 736 children in Sinan woreda, northwest Ethiopia, found that 15% of children were consuming vitamin A-rich fruits and vegetables . AnotherIn this study, residential availability of plant-based vitamin A-rich items had no marked association with consumption, only a small effect of availability of vitamin A-rich fruits. This is contrary to the previous cross-sectional studies that found an association between availability fruits and vegetables in residential food environment and consumption ,53,54. IIn this study, maternal education was positively and strongly associated with children consumption of plant-based vitamin A-rich diet. Higher educational attainment is known to be an important factor for attitudes towards the consumption of the vitamin A-rich plant sources food groups ,26,62,63Children from the higher wealth status households had higher odds of consuming plant-based vitamin A-rich food. Household wealth status as measured in this study reflects on cumulative assets and resources  and coulAlthough we were not able to explore social norms related to food consumption in this study, there is a growing recognition of social norms as an important factor influencing food consumption in low-income settings . Social The strengths of the study include the inclusion of a large sample of preschool children and using observational checklist to assess the local residential food environment , as recoThe consumption of plant-based vitamin A-rich food groups was low in Addis Ababa and had a positive but weak association with residential availability of vitamin A-rich fruits in the residential food environment. Consumption of plant-based Vitamin A-rich food was strongly associated with household wealth and maternal education. Further mixed method research is highly recommended to fully understand food consumption in children; qualitative research is required to understand the culture, belief, and preferences, and prospective quantitative for precisely measuring accessibility and consumption.


As the rage of coronavirus disease 2019 (COVID-19) pandemic continues to spread globally, much effort is being directed to contain it through various efforts – genomic studies, drug discoveries, clinical trials, vaccine development, and the innovation of diagnostic techniques. However, some pertinent areas involving accurate and sensitive diagnostics, immunoglobulin specificity, evolution of mutant strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the drug combination strategy to combat it still require more attention.This review critically examines the COVID-19 response and containment operations. It also addresses some standing challenges involving the areas of diagnostics, vaccine development and prospect, and treatment strategies in relation to antiviral drug treatment and immunotherapy. Designated set of keywords such as “SARS-CoV-2;” “coronavirus;” “severe acute respiratory syndrome coronavirus;” “repurposed;” “vaccination;” “containment;” “laboratory diagnostic;” “immunotherapy;” “antiviral;” “antiparasitic;” “antibiotic;” “antiprotozoal;” “antibody;” “anti-inflammatory;” “antitumor;” “corticosteroid;” “hypertensive drug;” “statin;” “supplement;” and “biological” along with “COVID-19” were inserted on electronic databases to retrieve articles and clinical trial information relevant to the study objectives. The search databases included ClinicalTrials.gov, NIH.gov, PubMed, Scinapse, CINAHL, Medline, Google Scholar, Academic Search Premier, SAGE, EBSCO Host, and Scopus.The difficulties associated with SARS-CoV-2 rapid mutations are unceasingly evolving and re-evolving. These pose serious concerns and downplay the efficacy and effectiveness of the current pipeline antiviral drugs and vaccines. Entities encompassing immunotherapy, antiviral drug therapies, viral genomics, protein-protein interaction, and improved diagnostics as well as drug combination strategy against the emerging genetic variability of SARS-CoV-2 were critically appraised. This study suggests that robust collaborations in the development of more sensitive, rapid and accurate diagnostics, development of immunoglobulin specific agents and improved anti-viral treatment focus against multiple mutant genes of SARS-CoV-2 should be aggressively pursued for the overall benefits of COVID-19 patients. The year 2019 ended with a global alarm in the form of an outbreak of a new strain of coronavirus called the Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2). On December 31, 2019, the World Health Organization (WHO) alerted the global health community of the occurrence of a cluster of pneumonia cases in Wuhan city in the Hubei Province of China [Recently, a big concern erupted over the dynamic antigenic drift of SARS-CoV-2 due to the discovery of about 14 mutant strains. From the available report, the existing immunogens and diagnostic reagents are normal products of the sequence of spike proteins from the index strain from Wuhan . By indiMany therapeutic agents have also been tested against SARS-CoV-2, so far, very few remain hopeful. Even though there is currently no specific drug available to treat COVID-19, a number of clinical trials are premised on repurposed drugs, biologicals, and occasionally dietary supplementations. These therapeutic agents are believed to serve various curative and preventive purposes either alone or in combination. Major classes among these medications are: Antivirals ; broad spectrum anti-parasitics (such as nitazoxanide); broad spectrum synthetic serine protease inhibitor (such as nafamostat); antimalarials ; antibiotics (such as azithromycin); antibodies/biologicals (such as interferon b1b and tocilizumab); and antitumor drugs (such as ruxolitinib), among others -6, TableFurthermore, studies into the development of COVID-19 vaccines are underway with some vaccine trials showing promising outcomes. It is important to note that the emergence of SARS-CoV-2 rapid mutations may prompt various challenges against the success of the ongoing vaccines, including potential immunopathological reactions based on the knowledge of vaccine development from MERS and SARS ,41. It iThe present report, therefore, examines and addresses some current, budding and future challenges, which include diagnostics, vaccine development and prospect, and treatment strategies in relation to antiviral therapy. It also offers some useful research information to the body of available data, which may facilitate the containment and response operations against the global battle of COVID-19.Familial and nosocomial contacts and community spread fuel and sustain the current rapid human-human transmission of SARS-CoV-2 virus in many countries . DespiteThe SARS-CoV-2 virus is a Beta-coronavirus, same as MERS-CoV and SARS-CoV; all the three viruses have their origins in bats. However, in the case of SARS-CoV-2, it is pangolins that have somewhat cautiously been implicated as the intermediate hosts ,46. ReceBecause there is lack of a definite answer regarding whether the index case of COVID-19 was really due to zoonotic transmission, the current pandemic situation continues to generate misconceptions and misinformation in the public space . One of According to the Chinese Center for Disease Control and Prevention (China CDC), clinical manifestations of COVID-19 are used in categorizing the patients into three disease groups- mild, severe, and critical. The mild COVID-19 manifestation category involves 81% of the patients. They often show no signs of pneumonia, or occasionally develop a mild symptom. However, the severe and critical cases present with a wide range of symptoms and pulmonary dysfunctions. Severe cases of COVID-19 occur only in 14% of patients, with the critical ones occurring only in 5% . Asymptoet al. [Several laboratory diagnostic methods – RT-PCR, serological tests such as ELISA among others have been developed and are currently in use. However, studies show that there is still a serious concern about the reliability of the major diagnostic tools for COVID-19 detection ,53. The et al. .st day of symptom onset and 20% 3 days later [In a study that involved a systemic review of 957 patients, it was observed that false-negatives in RT-PCR assays could be as high as 29% . A similys later . MeanwhiIn addition to molecular diagnostics, various rapid point-of-care kits for testing SARS-CoV-2 antibodies have been manufactured and marketed far and wide. These tests are basically qualitative and thus can only detect whether SARS-CoV-2 antibodies are present or not . Besidesnd week following the manifestation of symptoms [Serology is fast evolving as a vital diagnostic tool for COVID-19 especially in spotting individuals with immunity against the SARS-CoV-2 infection, over time. Serological tests may be useful only for patients who present late, especially after the first 2 weeks following the onset of COVID-19 symptoms . Even mosymptoms . In otheThe common approaches of detecting asymptomatic patients are through massive screening and good follow-up. However, to wait for possible development of symptoms in both presymptomatic and “asymptomatic” individuals may not represent the best approach since these groups of patients could still fuel the contagion. Therefore, a rapid point-of-care test with improved sensitivity and specificity is the required tool. To achieve this, the Food and drug Administration (FDA) must lay down a “gold standard” test for all COVID-19 diagnostic tests as a reference point. Apart from the diagnostic methods, other challenges such as sampling and transportation problems are fast evolving and contribute to the unreliability of test outcomes. Among the sampling related factors are varying anatomic sites, improper labeling, and wrong virus cycle timing.While inaccurate diagnostic results constitute a challenge to the containment of the pandemic, it is suggested that researchers should focus inwards on a range of methodological expertise, where accurate and early detection of SARS-CoV-2 could be made possible soon after contracting the disease. A previous report showed the potential use of respiratory virus testing panel (RVTP) for rapid diagnosis of COVID-19 , especiaThe purpose of antiviral therapy is to lower viremia in patients in the acute phase of infection, to allow the body to recover, and to give the immune system time to mount up a specific response that will neutralize the pathogen and halt its continued spread. According to a recent report, there have been few completed clinical trials on the efficacy of antiviral therapy in the management of COVID-19 patients . One of Another antiviral agent Remdesivir, initially used in the therapeutic management of Ebola patients, is still undergoing wide-scale; multi-center clinical trials and the preliminary results suggest its efficacy in the treatment of patients with severe COVID-19 . RemdesiIn another recently concluded clinical trial, Veklury (Remdesivir) was superior to placebo in shortening the time to recovery in adults who were hospitalized with COVID-19 and had evidence of lower respiratory tract infection . To helpMoreover, other studies focusing on the structural genetics  and mRNA biological mechanisms of SARS-COV-2 pathogenesis and immune evasion of the host cell will be beneficial in unlocking regions for drug targets, vaccine delivery and host immunological response. By addressing the therapeutic challenges based on the therapies that target the host-virus interface, where the emergence of mutational resistance is arguably less likely, could potentially present durable, broad-spectrum treatment modalities . This coin vitro experiments demonstrated strong upregulation of inflammatory cytokines at the protein level. It is believed that these agents and diagnostic techniques could offer various potentials for viral inhibition; activation of host immunological response by T and B cells associated cellular proteins and the monitoring of disease duration.Scientists have been able to unwind the SARS-CoV-2 host infectivity fuelled by enzymatic and antibody kinetics. SARS-CoV2 infection regulates host kinase signaling and virus kinase phosphorylation with its activity driven by host proteome . The topThe use of intravenous immunoglobulin (IVIg) therapy shows potential value as an effective adjunct measure in the treatment of several acute infections, including viral pneumonias such as SARS-CoV-2 . AccordiHowever, a separate report implies that there is a limited benefit of IVIg therapy. It concluded that the treatment efficacy of IVIg would be better only if the immune IgG antibodies are pooled from the patients who recovered from COVID-19 in the same locality such as in the same city or the surrounding area. This can raise the possibility of neutralizing the virus . The inhad infinitum in cell culture vats using hybridoma technology. Hybridoma technology could circumvent the need to pool intravenously or recruit patients who recovered from the disease once the genetic variants are fully identified. This may remove the barrier of the limited amount of harvested sera, and obviate the problem of the evolving constant mutation by the virus, using specific monoclonal antibodies through this technology. In this process, an antigen (or its epitope) is injected into a mammal to stimulate its immune system’s B-cells and produces neutralizing antibodies specific to the antigen. Furthermore, the antibody-producing B-cells are harvested and fused with a myeloma  in vitro to produce a hybrid cell line (a hybridoma), which retains the antibody-producing ability of the B-cell and the reproducibility of the myeloma.At present, various Igs are showing fruitful experimental outcomes as a promising class of drugs, it is believed that these proteins can, therefore, be produced A collection of various SARS-CoV-2 hybridomas from varying genetic mutants and preparation of a range of serotypes from immunized cells, followed with a proper characterization and purification processes could be a novel idea to produce cocktails of SARS-CoV-2 blocking monoclonal antibodies. Likewise, the use of Ig combination specific to different antigenic sites from different strains may limit the problems of treatment resistance occasioned by genetic variants and immune escape and thus offer a useful treatment option.The SARS-CoV-2 has demonstrated a remarkable ability to mutate. There has been an identified unexpected relationship between the SARS-CoV-2 mutation densities and viral transmission dynamics at different levels among human populations. A total of 14 new strains of the virus apart from the one originally identified in Wuhan have been characterized, and each has reportedly fueled regional epidemics such as those witnessed in Asia, Europe, North America, and Latin America . Spike mIt is important at this juncture, to add that evolving mutational significance in SARS-COV-2 termed synonymous and non-synonymous mutations is imminent. About this, mutational changes have been identified from COVID-19 cases in the highest hit countries including the United State of America (USA) and United Kingdom (UK) . StudiesThere is good news about the emergency use authorizations (EUAs) of COVID-19 vaccines sponsored by the Pfizer/BioNTech, Moderna, and AztraZeneca. The U.S.- FDA has recently approved some new recombinant protein-based, non-replicating subunit RNA vaccines against COVID-19. So far, the Phase 3 clinical trial results show that these vaccines can be safe and effective for use. However, this is EUA and not a full approval. According to the FDA , EUA is It is believed that the current demanding COVID-19 situations in places like the United States and some parts of the Europe had called for the emergency authorization. Many questions in association with these vaccines are yet unanswered. It is reasonable to accept that there are potential risks and fears of unknown regarding these new vaccines. But making these vaccines hastily available faster than the usual process should be less contemplated against the risk of infection with COVID-19 itself. However, it is believed that when productions of these vaccines increase and become more readily available and when many populations are vaccinated, there could be possible emergence of unknowns at any time. These unknowns will prompt scientists to continue to ask questions. It is important that some of the puzzles about emergency use of COVID-19 vaccines be brought to the limelight of discussion, especially now that there seem to be inadequate time to follow-up with the trial participants before the emergency approval. Now that vaccination already kick started, how long will the vaccine protection last? From participant recruitment to FDA-emergency approval, the process of clinical trials of these vaccines took less than 6 months. Therefore, it is believed that there were no adequate follow-ups to answer this question. Similarly, there is no current available data to understand whether the vaccines will require booster shots and the perfect time these might be expected.Besides, the main goal of COVID-19 vaccines is to prevent personal infection. Then, will the vaccinated individuals still prevent the spread of SARS-CoV-2 virus to non-vaccinated individuals? Even with the high level of assurance being provided by the vaccine companies regarding their efficacies  against all forms of SARS-CoV-2 mutant strains, it remains to be acknowledged whether the vaccinated individuals can still spread the infection or not. While in the present situations, it may be virtually impossible to vaccinate everyone due to the logistic and economic reasons, this question demands immediate answer in containment operations.In addition, the available vaccines data did not provide information regarding effectiveness of the vaccines in specific groups of people such as asymptomatics, immunocompromised, previously infected individuals, pediatrics, pregnant, and breastfeeding women, among many others. It is important to note that “efficacy” in clinical trials is not tantamount to “effectiveness” in clinical applications to all population groups. As at the time of writing this report, none of the clinical trials have answered questions regarding these specific individuals, yet they were so listed in their exclusion criteria in clinical trial statement .Furthermore, with the euphoria of arrival of the first COVID-19 vaccines, the virus seems to continue “re-strategizing” its battle with the emergence of new mutant strains, rapidly spreading, and affecting younger populations . Now thaDetailed information about the biology of SARS-CoV-2 is currently unknown. However, more information on the ecology of the virus is now in the limelight. The problem of SARS-CoV-2 rapid mutations is an emerging area of concern demanding urgent consideration in clinical trials and patient management. Vaccines usually become ineffective when a virus mutates. Likewise, drug resistance ensues when the genetic component of a virus is unstable. Ongoing clinical trials and current patient management on COVID-19 would achieve landmark success if the following are considered: (i) Improved rapid, sensitive and accurate diagnostics and development of a standard test, (ii) addressing the constant evolution of SARS-CoV-2 mutant strains, (iii) addressing the problem of immunoglobulin specificity prospectively, and (iv) Improving antiviral combination strategy against emerging genetic variability.


Solid organ transplantation is the best therapeutic option for the patients who are suffered from end-stage organ failure. In practice, the organ transplantation is mainly used as either a form of life-saving or life-enhancing. However, due to the donor organ shortage crisis, not every patient on the waiting list can receive a donor organ. During the past few decades, with the great development of surgical skills, post-operative monitoring and care, and immunosuppressive agents, the short-term graft survival has been significantly improved after organ transplantation, indicated by as high as 95% of survival rate . NeverthA diversity of innate immune cells has received much attention towards the understanding of CAR. Increasing evidence focuses on the profound roles of innate immune cells, such as NK cells, macrophages, and neutrophils, in the late phase change of the allografts. Emerging attention has been paid to the intragraft macrophage infiltration in the immunopathological characteristics of CAR. It has been well established that M1-like macrophages are inclined to produce pro-inflammatory cytokines TNF-α, IL-6, and IL-1β, mediating IRI in the early stage after transplantation. As pro-/anti- inflammatory activation and tissue repair co-exist, grafts may undergo dynamic change. Failing to control or prevent acute inflammation may result in chronic inflammation, attributing to establishment of allograft inflammatory fibrosis and gradual deterioration in functions.Zhang et al. have reviewed the roles of macrophages as a pivotal part of innate immunity in CAR. In their review, the diverse functions of M1 and/or M2 macrophages that drive different pathophysiological mechanisms in the acute or CAR are elaborated. Importantly, despite the fact that the predominated effects of adaptive antibody-mediated rejection on the loss of the grafts, the innate-immune-mediated fibrotic rejection triggered by the macrophages should not be neglected. The pathogenesis of the tissue fibrosis is a shared and central part of numerous pathologies, including autoimmunity, metabolic disorders, and graft rejection. The M2 macrophages not only contribute to anti-inflammation in the very early stage of graft survival, but also promote fibrotic processes via producing TGF-β1 and VEGF. This review provides us with better insights into the crosstalk between the macrophages and CAR.+CD163+ macrophages (M2 macrophage) tend to increase in grafts with chronic antibody-mediated rejection as compared those with acute antibody-mediated rejection and T cell-mediated rejection, suggesting that these macrophages could promote the chronic progressive injury  functions as a newly identified chemokine that could interact with C-C motif chemokine receptor 2 so as to mediate macrophage infiltration in local tissue, which may recruit the macrophages and promote the intimal arteritis, resulting in allograft lost in cABMR. This study may indicate PSMP may be a potential histopathological diagnostic biomarker and therapeutic target for kidney transplant rejection. However, whether PSMP plays the same role as in other organ transplants is not clear.Nishi et al. for the first time have reported that hydrogen benefits long-term prognosis of kidney transplants in a minipig model of the ischemic kidney transplantation and can inhibit chronic rejection response under a strict multi-immunosuppressant protocol.At present, the organ donors for organ transplantation around the world are mainly from Donation after Cardiac Death (DCD) donors . HoweverGui et al. have shown that the autophagic activity temporarily increases at the early stages of allograft transplantation, and it gradually decreases as ATG16L declines. ATG16L-dependent autophagy, as a cytoprotective process, could attenuate the transplanted kidney interstitial fibrosis via the regulation of the EndMT induced by IL-1β, IL-6 and TNF-α.Autophagy is a cellular physiological process responsible for protein and organelle degradation as a mechanism of cytoprotection against stress . EndotheZhang et al. have reported an interesting phenomenon indicating that ST2 deficiency in either allografts or recipients oppositely affects the cardiac allograft vasculopathy/fibrosis via differentially altering immune cells infiltration, suggesting that interrupting IL-33/ST2 signaling locally or systematically in heart transplantation may benefit the prevention of cardiac allograft vasculopathy. Nian et al. have also demonstrated that treatment with αIL-21R shifts the Tfh/Tfr balance toward DSA inhibition, which means that αIL-21R may be a potential therapeutic agent to prevent the chronic antibody-mediated rejection in organ transplantation. Finally, Li et al. have reported that mTOR deficiency enhances the immunosuppressive function of M-MDSCs and prolongs mouse cardiac allograft survival.Yang et al. have reported that artemisinin, a well-known anti-malaria agent, can effectively inhibit multiple lymphocytes, resulting in prolongation of cardiac allograft survival in a rat model of cardiac allotransplantation, and Zhou et al. have showed that curcumin, a natural polyphenol compound extracted from turmeric alleviates IL-6–dependent EndMT by promoting autophagy in vitro and in vivo in a rat model of kidney transplantation.To suppress the host immune response to the graft and to improve the recipient’s tolerance to the transplant remain a primary focus in organ transplantation. Traditional Chinese medicine is an indispensable part in the health care in China. During the past decades, the extracts of Chinese medical herbs and their derivatives have been used in the treatment of immune- and non-immune-mediated diseases. via releasing cytokines, chemokines, and extracellular vesicles and so on -based therapy emerges as an effective method for immunomodulation after transplantation . MSCs arnd so on .Qin et al. have demonstrated that melatonin can synergize with MSCs in the inhibition of chronic allograft vasculopathy in a mouse model of heterotopic aortic transplantation via strengthening immunomodulatory effects of MSCs. Zheng et al. review the recent development of MSCs-derived exosomes in preventing the organ transplant rejection, which may provide new strategies for improving the long-term prognosis of organ transplantation patients. Surprisingly, Wei et al. have conducted a clinical trial to confirm the clinical efficacy of MSCs. In their clinical trial, kidney recipients with biopsy-proven chronic active antibody-mediated rejection (cABMR) are divided into Regimen 1  and Regimen 2 . Contemporaneous cABMR patients who did not receive Bone marrow-derived-MSCs are retrospectively used as a control group (n = 30). Kidney allograft recipients with cABMR are tolerable to BM-MSCs, and the immunosuppressive drugs combined with intravenous BM-MSCs can delay the deterioration of allograft function, probably by decreasing DSA level and reducing DSA-induced injury.We hope that this Research Topic could provide a different perspective towards a further understanding of CAR and novel therapeutic strategies for the prevention of the CAR in the post-transplant care in the near future.DK: first draft of manuscript writing. CD: manuscript editing. HW: financial support, administrative support, manuscript writing, final revision and approval of manuscript. All authors contributed to the article and approved the submitted version.This work was supported by grants to HW from National Natural Science Foundation of China (No. 82071802), Li Jieshou Intestinal Barrier Research Special Fund (No. LJS_201412), and Natural Science Foundation of Tianjin (No. 18JCZDJC35800)The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Since emerging in December 2019, the SARS-CoV-2 virus has caused over three and a half million deaths worldwide by coronavirus disease (COVID-19) at the time of writing. Despite impressive scientific progress, variants of concern continue to arise, and global distribution of vaccines and therapeutics is lacking, leading to devastating outbreaks in certain parts of the world. To combat this, the research community needs to utilise appropriate model systems to study the virus and disease. Disease Models & Mechanisms, as an open-access biomedical journal, advocates that this research, and the resulting resources that are generated, need to be accessible and shared globally.US government is now supporting a waiver of patent protection for COVID-19 vaccines to enhance accessibility to vaccines worldwide.The scientific community's response to the COVID-19 pandemic has been remarkable. Massive sequencing efforts help us track this novel virus and its variants, and a preprint has shown that rapid tests can now accurately identify up to 90% of cases within one hour . TreatmeCOVID-19 dashboard at the time of writing. This was linked to the emergence of the Delta variant that – data from COVID-19 Genomic Surveillance tool provided by the Wellcome Sanger Institute suggests – is more transmissible than the Alpha variant, first identified in the United Kingdom. The Delta variant is spreading globally, and Nepal now has more cases than India relative to population size. With equally devastating effects, the Gamma variant has emerged in Brazil, where the WHO COVID-19 dashboard stated the death toll had passed 400,000 at the time of writing. This variant is up to twice as transmissible, and evidence indicates it may be able to evade immunity acquired from previous infections.Despite these accomplishments, several countries are still overwhelmed with the scale of the pandemic and the WHO indicates that 2021 may be a worse year for the pandemic than 2020. A devastating second wave of COVID-19 in India has peaked with at least 400,000 daily cases and 28 million total cases, as stated on the WHO in vitro studies can help delineate the mechanisms of SARS-CoV-2 infection and transmission on a cellular level, and provide a platform for screening for therapeutic inhibitors chloroquine, which was identified in cell-line screens as a potential therapeutic for COVID-19 but proved ineffective in the clinic , cynomolgus macaques (Macaca fascicularis) and African green monkeys (Chlorocebus aethiops) – are considered the most-representative animal models for studying SARS-CoV-2. Despite displaying mostly mild clinical disease, a study – yet to be peer reviewed – found that high viral replication and histopathological changes can enable vaccine efficacy and safety studies in these models (Animal models are needed to study different stages of SARS-CoV-2 infection and COVID manifestation – including long COVID, as well as the demographic differences in humans, such as increased susceptibility to severe symptoms with age . Owing te models  preprinte models  preprinte models .Novel CACE2 mouse strain in 35 days, which is a significant development as rapid model generation is pertinent in a pandemic setting (Posing a challenge to the use of mouse models, wild-type mice are inherently resistant to SARS-CoV-2 infection because the spike protein does not effectively interact with the murine Ace2 receptor . Transge setting . Mouse m setting . Nonethe setting  preprintNo single model can fully capture the manifestation of COVID-19 in humans. Indeed, some approaches are incapable of modelling specific aspects of COVID-19 but remain useful for drug screens or vaccine efficacy studies. To combat this, many studies investigating COVID-19 are now using a combination of models owing to their individual benefits. This pandemic has also encouraged investigation of viruses in non-laboratory animals to understand the transmission between species and to study zoonotic viruses before they emerge as human pathogens. A recent outbreak in a mink breeding farm, reminds us of the potential consequences of transmission between species and the relevance of studying non-laboratory animal models  preprint700 scientists wrote to their government requesting easier access to clinical COVID-19 data and the data from a large-scale sequencing study that is monitoring SARS-CoV-2 variants. As an Open Access journal publishing research that strives to understand and model disease, including COVID-19, DMM aims to continue supporting this global scientific effort. The power of sharing data worldwide has been proven by scientists – such as Malik Peiris and Yi Guan, whose research into Influenza A H5N1 and SARS-CoV-1 was instrumental in containing and preventing previous pandemics – and has enabled formation of world-wide pandemic strategies for SARS-CoV-2, including vaccine development. However, a critical issue remains: although we have effective vaccines, they are not sufficiently accessible worldwide and mortality among unvaccinated individuals is still remarkably high. Therefore, we need to support the development of COVID-19 disease models to continue research into therapeutics and vaccines for global distribution. Access to this progress requires us to share vaccines, resources, therapeutics and knowledge worldwide, to enable swift and well-informed responses to this rapidly changing pandemic.With these crucial research studies emerging, the issue of accessibility of scientific discoveries and data within scientific communities and beyond has become more prominent. This has been highlighted in India, where more than


We present a case of a pediatric patient with symptomatic leukemia involving the heart without bone marrow involvement. The case is followed by a literature review of advances in leukemia treatment including immunotherapy, CAR T-cell therapy, improvement in the treatment of graft-versus-host disease, and the applicability of these treatments to leukemia involving areas outside of the bone marrow. We also explore the feasibility of treatments such as CAR T-cell therapy and blinatumomab and the associated risks for treating patients with leukemia infiltrating the heart.Isolated extramedullary relapse of acute lymphoblastic leukemia (ALL) occurs in soft tissues and various organs outside the testis and central nervous system. Treatments such as hematopoietic stem cell transplantation and more novel modalities such as immunotherapy have eradicated ALL at extramedullary sites. In some instances, survival times for relapsed ALL at these sites are longer than those for relapsed disease involving only the bone marrow. Isolated relapse of ALL in the myocardium is rare, especially in children, making diagnosis and treatment of it difficult. More recent treatment options such as chimeric antigen receptor T-cell therapy carry a high risk of cytokine release syndrome and associated risk of worsening cardiac function. Herein we present the case of an 11-year-old boy who presented with relapsed symptomatic B-cell ALL in the myocardium following allogeneic hematopoietic stem cell transplantation. This is an unusual presentation of relapsed ALL and this case demonstrates the associated challenges in its diagnosis and treatment. The case report is followed by a literature review of the advances in treatment of pediatric leukemia and their application to extramedullary relapse of this disease in particular. Isolated symptomatic extramedullary relapse (EMR) in the myocardium is an uncommon phenomenon that has been described in rare instances in adult and pediatric acute lymphoblastic leukemia (ALL) patients. The literature includes a report of a 47-year-old man with isolated B-cell ALL relapse involving the myocardium who eventually died of cardiac arrest secondary to heart failure and complete atrioventricular (AV) blockage and a 5-year-old girl with initial isolated cardiac involvement of T-cell ALL but eventual progression and death ,2. GivenWe present an 11-year-old African American boy who initially presented with recurrent right thigh and cheek pain and numbness. A bone marrow (BM) aspiration and biopsy confirmed the diagnosis of Philadelphia chromosome-negative B-cell ALL. The clinical characteristics, including initial lab results, are summarized in The patient proceeded to consolidation chemotherapy. He experienced cranial nerve deficits characterized by right facial numbness, intermittent double vision, unusual sensation and taste, and excessive salivation. He also complained of worsening and persistent right thigh pain. Due to concern for leptomeningeal disease, the patient underwent MRI of the brain and the spine. Imaging of the brain was unremarkable, but that of the spine showed resolution of prior enhancements, a decrease in a prior enhancing focus at the L3 vertebra, and nothing suspicious for leukemia involvement. Cerebrospinal fluid analysis was normal, as well. Due to extensive clinical neurological involvement of his leukemia, the patient received craniospinal irradiation of the brain at 18 Gy in 10 fractions followed by proton therapy to the spine at 15 cobalt gray equivalents in 10 fractions and chemotherapy according to Pediatric Oncology Group protocol POG9412 . After cThe patient proceeded to total-body irradiation-based myeloablative hematopoietic stem cell transplantation (HSCT) with a single unrelated umbilical cord blood unit . Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus and mycophenolate mofetil. BM evaluation on day +38 after HSCT showed 6% blasts according to morphology, with flow cytometry showing 2.5% leukemic blasts, indicative of residual acute leukemia. A repeat BM aspiration on day +51 following HSCT revealed MRD-negative remission. Treatment with mycophenolate was discontinued on day +57, but that with tacrolimus was continued. Due to decreased appetite and concern for acute GVHD, the patient underwent upper and lower endoscopy on day +122 and was noted to have grade II acute GVHD of the upper and lower gastrointestinal system that was managed with systemic corticosteroids.About 8 months after HSCT, the patient was admitted to our hospital for fever, shortness of breath, and a chest X-ray showing significant pleural effusions requiring thoracentesis. He was admitted to the pediatric intensive care unit, where he underwent endotracheal intubation due to acute respiratory failure. He experienced rapidly progressive bradycardia with loss of consciousness requiring cardiopulmonary resuscitative efforts. An echocardiogram revealed echogenic areas over the basal interventricular septum indicative of infiltration  with mil18F-fluorodeoxyglucose-avid disease involving the sphenoid bone of the skull, right femoral diaphysis and sacrum, soft tissue of the right orbit, right and left ventricles of the heart, mesentery, and retroperitoneum  pediatric leukemia. The use of these new therapies has produced better outcomes than has salvage chemotherapy, with remission rates for CAR T-cell therapy that are almost twice as high as for those of conventional chemotherapy .Blinatumomab is a bispecific T-cell engager that targets CD19-expressing leukemia cells. When used in the postinduction chemotherapy setting, blinatumomab has improved event-free and overall survival rates in pediatric patients with first relapse of high-risk B-cell ALL ,38,39,40Inotuzumab ozogamicin is an antibody directed against CD22 and conjugated with the cytotoxin calicheamicin whose use leads to uptake and killing of leukemia cells that highly express CD22. In trials, inotuzumab ozogamicin has proven to be effective in inducing remission of r/r ALL with minimal adverse effects in the majority of patients . The benWhereas HSCT, CAR T-cell therapy, blinatumomab, and inotuzumab ozogamicin are commonly used for treatment of r/r medullary leukemia, common treatments of EMR of leukemia are lacking . In caseHSCT has been successful in curing isolated EMR, in some instances resulting in 10-year overall survival rates nearing 60% and disease-free survival rates of about 50% ,47. MoreHowever, authors have reported that immunotherapies such as CAR T-cell therapy can be effective in eradicating extramedullary disease ,49,50. CThe effectiveness of CAR T cells in treatment of EMR of leukemia may lie in their ability to travel to extramedullary sites as well as remain in the BM and peripheral blood . CAR T cOverall, standard guidelines for the treatment of EMR of ALL are lacking, although irradiation and combination chemotherapy are associated with improved outcomes ,59,60. FWhereas CAR T-cell therapy may be somewhat effective in eradicating EM ALL, blinatumomab has not demonstrated a similar ability to induce remission in EM ALL due to either resistance to the drug or the emergence of a CD19-negative leukemia cell line ,62,63. AAlthough data regarding inotuzumab ozogamicin use for EM ALL are limited, preliminary data demonstrated that it may have a role in treatment and eradication of extramedullary disease ,66,67. DIL-7Rα gene has been shown to promote the survival of T-cell ALL (T-ALL), especially when associated with cytokine receptor-like factor 2 (CRLF2), another gene mutation associated with pediatric ALL [IL-7Rα gene have been found in nearly 10% of pediatric leukemia cases, this pathway represents a fruitful opportunity for the development of an immunotherapy modality to target [α have also been found to interact with Janus kinase (JAK), leading to JAK phosphorylation and activation of downstream pathways such as signal transducer and activation proteins (STAT5) that can further lead to the proliferation of leukemia cells [α signaling, the PI3K/AKT/mTOR and JAK/STAT pathways are associated with rearrangements of the CRLF2 gene, leading to the development of Philadelphia-like (Ph-like) ALL, which can portend a poorer prognosis compared to those without the mutation [CRLF2 mutation [There are multiple molecular pathways, including the interleukin-7 receptor α (IL-7Rα) signaling pathway, that have been identified as possible targets of immunotherapy . Aberrantric ALL ,75. Conso target . IL-7 ania cells . Each coia cells . Anotheria cells . Similarmutation ,79. Drugmutation . Due to Despite the promising future of immunotherapy for EMR of ALL, cardiotoxicity is a risk with modalities such as blinatumomab and CAR T-cell therapy. Both are associated with CRS, which is the most common adverse event in the pediatric population receiving CAR T-cell therapy for r/r ALL, in some cases affecting 85% of patients and with nearly half of them needing intensive care ,81. DepePatients with ALL involving the heart also have a high risk of morbidity and mortality from immunotherapy due to prior exposure to cardiotoxic chemotherapy and radiation . MedicatTaking into account the cumulative effects of prior chemoradiation and the risk of cardiotoxicity from immunotherapeutic modalities such as blinatumomab and CAR T-cell therapy, patients who undergo these treatments are at significantly high risk for adverse effects due to cardiac events. The use of immunotherapy in these patients requires deliberation of over the risks and benefits of immunotherapy and appropriate diagnostic steps, such as an echocardiogram to measure LV ejection fraction, LV global longitudinal strain, and levels of cardiac biomarkers to evaluate and monitor the heart’s ability to compensate for negative effects that may arise due to adverse effects of immunotherapy, especially during episodes of CRS .Although isolated EMR following stem cell transplantation portends a poor prognosis for ALL, it is not significantly worse than that with BMR, with studies demonstrating that it is associated with better survival and a greater chance of cure ,86,87. IWe present herein the first documented biopsy-proven case of post-HSCT symptomatic B-cell ALL relapse within the myocardium that does not also involve the BM in a pediatric patient. Although patients with isolated EMR fare better than do those with EMR in combination with medullary relapse or isolated medullary relapse, our patient was stable for 8 months following HSCT before dying of cardiac failure. Isolated symptomatic cardiac relapse of ALL may be difficult to diagnose due to the location of disease, the need for invasive procedures required for accurate diagnosis, and care requiring cardiac critical care services. Currently, uniform guidelines for treating isolated EMR of ALL are lacking, although combination chemotherapy regimens with or without radiation therapy and HSCT have been somewhat effective. Although CAR T-cell therapy has been effective to a certain extent in controlling EMR, its use for isolated cardiac relapse is questionable due to a significant risk of adverse events related to its cardiotoxicity and inability of the heart to compensate for the sequelae of CRS. While our patient was unable to receive immunomodulating therapies such as blinatumomab or CAR T-cell therapy because these treatments had not yet been approved for pediatric use during the time of his illness, immunotherapies such as CAR T-cell therapy, T-cell-engaging antibodies, and monoclonal antibodies appear to be effective in treating EMR of ALL. These immunotherapies are potential modalities of cancer treatment, and studies suggest that they are treatment options that can target leukemia cells in areas of the body where conventional chemotherapy and HSCT have little to no effect on them.


Loneliness is significantly associated with health and well-being among oldest-old adults. Due to the outbreak of the COVID-19, physical and social distancing policies might elevate loneliness among the oldest-old population. This study examined the trends and changes in the prevalence of feeling lonely using the 2020 HRS COVID-19 module merged to the 15 waves of the HRS RAND longitudinal datasets from 1992 to 2018. A total of 14,371 respondents, including 614 respondents aged 80 years and older were included. Generalized linear models compared age group differences within the 2020 module. Generalized estimating equations assessed the longitudinal change at the individual level and the trend of feeling loneliness among oldest-old adults from 1992 to 2020. Loneliness was assessed with one item of the CES-D scale . After adjusting for demographic characteristics and health, the results showed that oldest-old adults were more likely to feel lonely compared to younger age groups (18% for 80’s vs. 14% for 50’s) during the early months of the pandemic. A longitudinal trajectory also showed that they feel lonelier than in prior years (19% in 2020 vs. 14% in 2018). However, compared to same-age groups from earlier years, a significantly lower prevalence of feeling lonely was observed (18% in 2020 vs. 27% in 1994). The results show that the outbreak of the COVID-19 may elevate feeling lonely, but the recent cohorts be less lonely than earlier cohorts. Future research should continue to explore protective factors for loneliness among oldest-old adults.


Our study shows that IgG4-ROD symptom duration is significantly positively correlated with relapse rate and negatively correlated with relapse time. Symptom duration was positively correlated with serum baseline IgG4, IgE, and eosinophil levels and asthma history, which were potential risk factors for disease relapse. We recommended that IgG4-ROD patients with symptom durations greater than 96 months continue to receive maintenance steroid therapy longer than 1 year postsurgery to reduce the relapse rate.IgG4-related disease (IgG4-RD) affects multiple organs and is characterized by immune-mediated inflammation and fibrosis; IgG-RD affecting orbital tissue is known as IgG4-related ophthalmic disease (IgG4-ROD). This research is aimed at exploring whether symptom duration and common serologic factors, such as IgG, IgE, and eosinophils, are potential risk factors for IgG4-ROD patient relapse after surgery and identifying possible causes of the positive correlation between symptom duration and relapse. This retrospective cohort study included 40 IgG4-ROD patients after surgery. Auxiliary inspection results were obtained before surgery and during follow-up, and relapse risk factors were identified based on previous studies. We used the Spearman rank correlation test to reveal the relationship between symptom duration and relapse time and identified the optimal cutoff value for symptom duration by X-tile. Then, we divided the patients into the long-duration and short-duration groups. Kaplan–Meier survival analyses and log-rank tests were performed to identify the relationship between symptom duration and relapse using X-tile software. Finally, we studied the relationship between previously studied relapse risk factors and symptom duration. The survival curves of the long-duration and short-duration groups were obviously different, and the baseline serum IgG, IgE, and eosinophil levels and asthma concomitant rate were significantly different between the long-duration and short-duration groups. Furthermore, the baseline serum IgG ( IgG4-related disease (IgG4-RD) is an immune-mediated inflammatory disorder with fibrosis that can affect multiple organs, and the affected organs can have tumor-like lesions and even failure . The hisMore and more attention paid to the diagnosis and treatment of this infrequent autoimmune disease since the publication of diagnostic criteria for IgG4-RD . In 2015Our study is a retrospective cohort study that included 40 IgG4-ROD patients after surgery. Our study describes the clinical characteristics and differences in serological indicators of each patient, explores and analyses whether symptom duration and serologic factors, such as serum IgE and IgG4, are potential risk factors for IgG4-ROD patient relapse after surgery, and tries to identify possible causes of the positive correlation between the duration of symptoms and relapse. We hope that this study will provide reliable predictors of relapse for IgG4-ROD and new recommendations for the rational treatment of IgG4-ROD.n = 40), and 4 patients were excluded from our cohort due to loss of follow-up. We diagnosed 21 (58.3%), 4 (11.1%), and 11 (30.6%) patients with definite, probable, and possible IgG4-ROD, respectively, according to the 2015 IgG4-ROD diagnostic criteria [This research was permitted by the Ethics Committee of Changzheng Hospital affiliated with Naval Military Medical University. All the patients enrolled in the study signed an informed consent form, and all of our procedures for experimental implementation complied with the Declaration of Helsinki. We included all IgG4-ROD patients who met the inclusion criteria treated in Changzheng Hospital from March 2013 to July 2020 in the cohort , ultrasound scanning (US), and magnetic resonance imaging (MRI). All tissues removed after surgery underwent pathological biopsy.We determined the time of onset during detailed medical history inquiry and diagnosis and treatment records provided by the patient. The time of onset was defined as the time when positive symptoms or signs appeared or when clinically significant auxiliary examination results appeared. After the operation, the patients went to the ophthalmology clinic of Changzheng Hospital for related examinations and follow-up at 1 month and 6 months later. Afterward, we sent questionnaires to the patients to investigate the relapse situation every year. The relapse time is defined as the reappearance of positive symptoms and signs, as well as the reappearance of diagnostic laboratory tests and imaging findings. An increase in serum IgG4 concentration alone cannot be considered a disease relapse. We determined the time from onset to treatment as the duration of symptoms.P < 0.05 [X-tile was used to identify the optimal cutoff value, and the statistical significance index was P < 0.05 . The obtThe predictors screened in this experiment to predict disease relapse include some common clinical features of IgG4-ROD, past medical history, and serological indicators, like gender ratio, the rates of having a history of asthma, baseline serum IgG4, IgE, IgG, and eosinophil counts, which have been suggested by previous studies to be predictors of IgG4-RD relapse , 14, 15.All patient clinical data were gathered and are listed in the tables and supplementary materials of this article. We present distributed normally distributed quantitative variables as the means ± SDs and present nonnormally distributed features as the medians (IQRs). We compared continuous variables using the Mann–Whitney test. The Spearman rank correlation test was used to quantify the correlations. We used the chi-square test to compare categorical variables. Then, we generated all figures with GraphPad Prism version 8.1.1  and performed all statistical analyses with SPSS Statistics version 24.0 .We enrolled 40 patients in our cohort. After excluding 4 patients who were missing the follow-up, 36 patients remained, and their clinical and demographic baseline features are shown in According to the clinical characteristics, eyelid swelling (77.8%) and exophthalmos (52.8%) were the most common clinical symptoms in IgG4-ROD patients, and the lacrimal gland was the most commonly affected organ/anatomical site (88.9%). The proportion of asthma history was 36.1%.r = −0.526, P < 0.05). We performed Kaplan–Meier survival analyses and log-rank tests to identify the potential relationship between the duration of symptoms and relapse. Based on the cutoff value calculated by X-tile  and a short-duration group (n = 26). The survival curves of the IgG4-ROD patients in the long-duration group and short-duration group are shown in P < 0.05), and the relative risk (RR) was 2.6 (95% CI 1.225-5.516), which indicates that symptom duration is strongly correlated with the disease relapse rate.The Spearman rank correlation test was used to reveal the relationship between the duration of symptoms and the relapse time, and the results are presented in A comparison of the baseline clinical characteristics between the patients in the two groups is presented in There are differences in serological indicators between the long-duration group and the short-duration group. Mann–Whitney tests were performed to analyze whether there were significant differences in serological indicators, including serum IgG4, IgG, IgE, eosinophil, and globulin levels, between the long-duration group and short-duration group. The results are presented in According to the results, we found that the levels of serum IgE, IgG, and eosinophils were significantly different between the long-duration group and short-duration group, which means that patients with a long duration of symptoms have higher baseline serum IgE, IgG, and eosinophil levels.r = 0.350, P = 0.037) and eosinophil  levels were positively correlated with the duration of symptoms, and the chi-square test results between the long-duration group and short-duration group were also significantly different. This suggests a longer symptom duration along with higher serum IgE and eosinophil levels, and patients with a longer symptom duration are more likely to suffer from asthma.We used the Spearman rank correlation test to identify the relationships between baseline serum IgE and eosinophil levels and symptom duration, and chi-square tests were conducted to verify the relationship between the duration of symptoms and the history of associated asthma. The results are presented in + plasma cell invasion. The lacrimal gland is the most common anatomical site of IgG4-ROD involvement [IgG4-related ophthalmic disease is a fibroinflammatory disease mostly characterized by IgG4olvement , 17, andolvement ; our resolvement , 20 and olvement .IgG4-ROD is a chronic illness, and the development of this disease involves a process of remission-relapse-remission . How to From our survival analysis results, we realized that there was a potential relationship between symptom duration and disease relapse: as the duration of symptoms increased, the relapse time was earlier, and the relapse rate also increased. Liu et al.  found thTo further explore the reasons for the high relapse rate of IgG-ROD due to the long duration of symptoms, we conducted a study on the relationships between common serological and clinical indicators and the duration of symptoms. The results show that a longer symptom duration causes higher serum IgE and eosinophil baseline levels, and patients with a longer symptom duration were more likely to develop asthma. Interestingly, serum baseline levels of IgE and eosinophils and history of asthma are all risk factors for IgG4-ROD relapse. Wallace et al.  found thOur research was retrospective, selection bias and recall bias probably occurred, and measurement bias may exist in different patients due to the different testing times and personnel of serological indicators. Furthermore, the sample size of the research is small and does not conform to the normal distribution, so many reasonable statistical methods cannot be performed. Whether the duration of symptoms is indeed an independent risk factor for relapse still needs to be further explored by expanding the sample size and using Cox regression analysis and other more convincing statistical methods. Moreover, due to the scarcity of IgG4-ROD patients and the limitations of retrospective studies, the experiment did not adopt 1 : 1 grouping. The patient's disease relapse time may not be completely accurate due to the limitation of the follow-up period. The duration of symptoms completely depended on patient self-report; consequently, the possibility of memory bias existed, although we carefully verified symptom duration. We plan to further explore whether the duration of symptoms is indeed an independent risk factor for relapse by expanding the sample size and using more convincing statistical methods in our future research.In conclusion, our research used the largest known cohort of patients undergoing surgical treatment for IgG4-ROD and for the first time explored the relationship between the duration of symptoms and the relapse of IgG4-ROD. Our study provides novel information about risk factors for IgG4-ROD relapse and found that the duration of symptoms of IgG4-ROD has a significant positive correlation with relapse of the disease. As the duration of symptoms increases, the relapse time becomes earlier, and the relapse rate also increases. The duration of symptoms is positively correlated with serum baseline levels of IgE, eosinophils, and asthma history, which are risk factors for disease relapse, suggesting that the prolonged duration of symptoms may lead to the accumulation of risk factors for the relapse of the abovementioned diseases and lead to relapse. For these reasons, we recommended that IgG4-ROD patients with symptom durations greater than 96 months continue to receive maintenance steroid therapy longer than 1 year after surgery to reduce the relapse rate. Our research provides theoretical support for advocating early treatment of IgG4-ROD and for the reasonable selection of treatment options; additionally, our study provides new directions and ideas for follow-up studies on the prevention of IgG4-ROD relapse and the identification of potential serologic biomarkers for predicting disease relapse.


COVID-19 presentations range from mild to moderate through severe disease but also manifest with persistent illness or viral recrudescence. We hypothesized that the spectrum of COVID-19 disease manifestations was a consequence of SARS-CoV-2-mediated delay in the pathogen-associated molecular pattern (PAMP) response, including dampened type I interferon signaling, thereby shifting the balance of the immune response to be dominated by damage-associated molecular pattern (DAMP) signaling. To test the hypothesis, we constructed a parsimonious mechanistic mathematical model. After calibration of the model for initial viral load and then by varying a few key parameters, we show that the core model generates four distinct viral load, immune response and associated disease trajectories termed “patient archetypes”, whose temporal dynamics are reflected in clinical data from hospitalized COVID-19 patients. The model also accounts for responses to corticosteroid therapy and predicts that vaccine-induced neutralizing antibodies and cellular memory will be protective, including from severe COVID-19 disease. This generalizable modeling framework could be used to analyze protective and pathogenic immune responses to diverse viral infections. The COVID-19 pandemic has been characterized by diverse clinical manifestations that have been associated with varying host immuno-inflammatory responses to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. These phenotypes, which include large numbers of asymptomatic carriers , have raIn the early stages of the pandemic, attempts had been made to predict the host immune and inflammatory responses to SARS-CoV-2 in the context of the known biology of other coronaviruses . More rede novo through the activation of innate immunity; however, recent evidence suggests that this pathway  depending on the relative interactions among virus-infected cells, the innate immune response to DAMPs that are released from damaged or dysfunctional tissue, and the adaptive immune response triggered by innate immune activation); 2) initial calibration of viral inoculum using published data on experimental SARS-CoV-2 infection; 3) further calibration of viral inoculum to data from COVID-19 patients followed by model simulations revealing distinct disease trajectories that correspond with clinical data from exemplary patients; and finally 4) simulations of anti-inflammatory therapy and COVID-19 vaccination.The model used in all simulations obeyed the following differential equations:whereandVC, is scaled such that a value of CV = 10−6 corresponds to one infected cell. I, D, and A have arbitrary units. Parameters are described in dik; dix; iainvx; and aik), while the others were fixed. The detailed derivation and motivation for the model are in the V.C In SARS-CoV-2 infection of rhesus macaque monkeys (6 50% tissue-culture infectious doses (TCID50). At a starting VC value of 1x106, our model predicted a peak time for the viral infection at 8 days. An exploration of the impact of increasing initial viral load on the time to peak infection for each COVID-19 archetype is detailed in VC value for human COVID-19 patients. This is difficult to do based on previously published data  score  patients), and ventilatory dependence (surrogate of respiratory distress), were used when available for patients; and I was compared to serial measurements of high-sensitivity C-reactive protein . Therapies that mitigate damage/dysfunction, most likely organ-supportive care in the ICU, as well as DAMP-targeted therapies . Anti-I treatment for this archetypal patient shown in I to levels that resemble a mild recovery case; however, in this Uncontrolled Infection archetype, this inhibits A from curbing the growth of VC, which reaches high, sustained levels . However, a similar implementation in which in silico 21-day corticosteroid therapy was delayed until Day 36 displayed a longer recovery and larger area under the curve for D (AUCD) over the time window compared to results with treatment started on Day 24 . We next sought to determine if our model could also reproduce the response to a shorter course of anti-inflammatory therapy, in this case a patient in their 50s with hypertension, chronic kidney disease, and obesity who developed severe acute respiratory distress syndrome due to COVID-19 and was administered corticosteroids. Based on the clinical characteristics of the patient, we simulated the administration of corticosteroids to the I to subsequently prime A in naïve individuals not previously exposed to SARS-CoV-2 (i.e. absent immune memory). The crucial difference of the vaccine relative to viral infection is that it induces innate inflammatory pathways (I) directly without requiring the induction of damage (D) to prime a virus-specific adaptive response (A). Thus, vaccination in theory provides a safe route for inducing immunity. Although the ensuing immune response may cause symptom-like side-effects, the amount of damage caused by this adjuvant-induced immune response (i.e. I ➔diD via k) are much reduced compared to those caused by the virus.Multiple COVID-19 vaccines are currently being deployed worldwide . As a fu5 infected cells 14 days following the second vaccination dose. In the simulations, the strength of the adjuvant to induce I as well as the effectiveness of the specific antibody response can be adjusted to inhibit the growth of the virus-infected cell population, VC. The matching control, non-vaccination scenarios presented assume only cell-mediated killing of VC. Thus, the vaccination protocol enables A to both inhibit growth of VC as well as to kill VC directly  and I  as well as the ratios of the AUCD-Vac to AUCD-NoVac for each of the core archetypes  and then those of the Recrudescence/Persistent Disease archetype, especially the recurrence scenario which was converted to recovery under vaccination simulation. For the ratios ≥ 1, this implies that the vaccination was not effective at reducing overall damage, such as in the Uncontrolled Infection archetype. Ratios much greater than 1 would imply that vaccination may be harmful, but this was not observed in the simulations.A in the model, implemented as a source constant, Ae, in the A equation (data not shown) and settled upon Ae=0.05 A-units as a reasonable intermediate level of existing immunity based on the dynamics of VC. The results (We next simulated vaccination in the context of fully developed immune memory (implemented as a single parameter rather than adding to the model detailed mechanisms of the formation of immune memory). We experimented with varying levels of an existing level of The overarching hypothesis of this study was that the SARS-CoV-2-mediated delay in pathogen-associated molecular pattern (PAMP) response that includes diminished type I interferon signaling, shifts the balance of the virus induced immune response to one that is dictated by damage-associated molecular pattern (DAMP) molecules. We reasoned that the current paradigm regarding the sequence of events that ensue in response to viral infection might miss a crucial role for DAMPs released secondary to tissue damage/dysfunction following viral infection, as opposed to the current dogma which focuses on virus-derived PAMPs as the main initiating response. A parsimonious mathematical model, which is based on the overarching hypothesis, revealed that this DAMP-dominated response can manifest different dynamics i.e. result in distinct viral load and disease trajectories that are referred to as archetypal COVID-19 responses or “COVID-19 archetypes”. Importantly, alterations of interactions among virus-infected cells, the magnitude of the innate immune response to DAMPs that are released from damaged or dysfunctional tissue, and the ensuing adaptive immune response triggered by innate immune activation are shown to underlie the distinct disease dynamics or archetypes.D) as a proxy for DAMP release. Notably, these earlier models do not include any variables accounting for adaptive immunity, and yet still predicted multiple, archetypal responses to infection or injury. Similarly, our theoretical model predicts distinct COVID-19 archetypes including mild scenarios, and data from incidental COVID-19 patients reflect these predictions.Multiple groups have generated mechanistic –68 and dD is a dominant instigator of I in COVID-19 is a novel explanation for why asymptomatic cases are so prevalent in such a deadly disease. Symptoms such as fever and malaise arise after I becomes sufficiently high. In the setting of viral infections for which there is immune memory, I is activated before or simultaneously with D and thus symptoms appear rapidly. With SARS-CoV-2 infection, I is induced much later at least in part due to virus-mediated suppression of anti-viral mechanisms . However, the molecular identity of D in the context of COVID-19 , is as yet unknown, though some have speculated that HMGB1 might play this role  are observed in controlled studies of SARS-CoV-2 infection in rhesus macaque monkeys  predicted to die in the absence of vaccination will not be rescued by vaccination is sobering. However, this prediction is for individuals that are infected shortly after vaccination, a potentially likely scenario in the context of “pandemic fatigue” and a desire to return to normal activities following vaccination. Our simulations suggest that given sufficient time for an appropriate degree of immune memory to take hold, all COVID-19 archetypes will be protected. These findings would suggest the need to remain vigilant for 1-3 months after vaccination. Notably, our simulations are not directly capable of addressing the issue of further virus transmission by vaccinated individuals.Our simulations also offer a nuanced and archetype-specific view into COVID-19 vaccination. Realistic simulations of primary vaccine responses, based on an initial activation of innate immunity due to innate immune sensing of RNA, show that vaccinated individuals will initially undergo an acute inflammatory response to the RNA itself. While our simulations did not point to any setting wherein this inflammation would reach a level similar to that of any of the archetypes associated with severe COVID-19, we cannot rule out individual circumstances wherein this inflammation could trigger inflammatory pathology. Importantly, once adaptive immunity is induced sufficiently, our simulations suggest that overall damage/dysfunction will be reduced in most patients with less severe or recrudescent/persistent disease manifestations, the finding that some archetypes  is that the model was calibrated to the initially described strain of SARS-CoV2; the multiple variants of this virus that have emerged  as compared to infection with SARS-CoV-2, in line with published findings (D and hence less I as compared to SARS-CoV-2 infection. Inhibiting I with corticosteroids in the case of influenza infection may benefit some patients (in cases where the I ➔ D ➔ positive feedback results in elevated inflammation) while harming those patients in which this feedback is not predominant (and thus inhibiting I with corticosteroids results in inhibition of A and consequent immunosuppression) with a population-level outcome of no net benefit. In the context of SARS-CoV2 infection, we hypothesize that corticosteroids help ~30% of patients (via inhibition of D ➔ I ➔ D) or indirect (by attenuating the negative feedback of I on A) effects. In contrast, SARS-CoV, MERS, Ebola, or Marburg virus infection would lead to a much larger D . This feature of self-limiting infection may also be part of the reason that the OC43 coronavirus today causes the common cold despite having been a cause of a pandemic in the 19th century . Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.JD conceived the study, performed computational studies, and wrote/edited manuscript. SP conceived the study, obtained and analyzed data, and wrote/edited manuscript. BR obtained and analyzed data, and edited manuscript. HS conceived the study, analyzed data, and wrote/edited manuscript. CC conceived the study, performed computational studies, analyzed data, and wrote/edited manuscript. YV conceived the study, analyzed data, and wrote/edited manuscript. All authors contributed to the article and approved the submitted version.YV was supported by NIH grant U01EB021960. SP was supported by NIH grant R21NS113055. CC was supported by the Intramural Research Program of the NIH, NIDDK.YV is a co-founder of, and stakeholder in, Immunetrics, Inc.The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Although the exact factors promoting disease progression in COVID-19 are not fully elucidated, unregulated activation of the complement system (CS) seems to play a crucial role in the pathogenesis of acute lung injury (ALI) induced by SARS-CoV-2. In particular, the lectin pathway (LP) has been implicated in previous autopsy studies. The primary purpose of our study is to investigate the role of the CS in hospitalized COVID-19 patients with varying degrees of disease severity.In a single-center prospective observational study, 154 hospitalized patients with PCR-confirmed SARS-CoV-2 infection were included. Serum samples on admission to the COVID-19 ward were collected for analysis of CS pathway activities and concentrations of LP proteins [mannose-binding lectin (MBL) and ficolin-3 (FCN-3)] & C1 esterase inhibitor (C1IHN). The primary outcome was mechanical ventilation or in-hospital death.The patients were predominately male and had multiple comorbidities. ICU admission was required in 16% of the patients and death (3%) or mechanical ventilation occurred in 23 patients (15%). There was no significant difference in LP activity, MBL and FCN-3 concentrations according to different peak disease severities. The median alternative pathway (AP) activity was significantly lower  in patients with death/invasive ventilation compared to patients without . An optimal threshold of <65.5% for AP activity was derived from a ROC curve resulting in increased odds for death or mechanical ventilation  even after adjustment for confounding factors. Classical pathway (CP) activity was slightly lower in patients with more severe disease . C1INH concentration correlated positively with length of stay, inflammatory markers and disease severity on admission but not during follow-up.in vivo leading to complement consumption and consequently to a significantly reduced AP activity in vitro. The LP does not seem to play a role in the progression to severe COVID-19. Apart from its acute phase reaction the significance of C1INH in COVID-19 requires further studies.Our results point to an overactivated AP in critically ill COVID-19 patients  In December 2019, a novel coronavirus was identified as the cause of a cluster of pneumonia cases in Wuhan, a city in the Hubei Province of China. It rapidly spread, resulting in an epidemic throughout China, followed by an unprecedented worldwide pandemic with more than 202 million identified cases and more than 4 million deaths  is the most abundant of the three ficolins in serum, and the only one that is expressed in the lungs even exceeding its expression in the liver . AlthougWith regards to COVID-19, it remains to be elucidated, which complement pathway crucially contributes to complement activation and its clinical consequences. Previous studies have pointed to the LP and alternative pathway (AP) , 33–35.Given the paucity of data regarding the lectin pathway of complement in SARS-CoV-2 infection, we aimed to investigate serum concentrations of two important PRR of the LP and of its predominant inhibitor (i.e. C1INH) as well as to clarify the role of complement pathway activities in a well-characterized cohort of COVID-19 patients with respect to severity and outcome.The study protocol was approved by the Ethics Committee of Northwest and Central Switzerland (EKNZ 2020-00769) with a waiver for informed consent. The study was performed in accordance with the latest version of the declaration of Helsinki and the guidelines for good clinical practice.This prospective observational cohort study was performed at a single tertiary care center in Switzerland. Consecutive patients with a SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) from a nasopharyngeal swab and admitted to the hospital between March and May 2020 were included. Serum samples were collected on admission to the COVID-19 ward during routine blood sampling, transferred to the laboratory immediately after sampling, centrifuged, aliquoted and stored at −80°C until measurement of the complement pathway activities and concentrations of MBL, FCN-3 and C1INH. According to the institutional protocol at that time most patients received lopinavir/ritonavir and hydroxychloroquine treatment, but not corticosteroids. In addition, patients who deteriorated with a C-reactive protein (CRP) above 70 mg/L and/or progressive lung involvement on repeat chest computed tomography (CT) scan were treated with tocilizumab (8 mg/kg body weight up to 800 mg with a repeat dose after 24 to 48 hours if required) on a compassionate use basis.Patients were excluded if they had refused the general research consent of our institution, if a serum sample was not available on admission or if patients were transferred to another institution within 72 hours (lost to follow-up).® Complement system Screen kit, Svar Life Science AB, Sweden) and C1INH antigen concentration  were determined on semi-automated platforms in the Clinical Laboratory of the University Hospital according to the manufacturer’s instruction and standard operating procedures. Low CP and AP activities are usually caused by in-vivo activated pathways with consumption of complement components, whereas low LP activity is usually due to low MBL concentrations.Complement pathway activities (WIESLABFor FCN-3 a research-use-only enzyme-linked immunosorbent assay (ELISA) kit was used according to the manufacturer’s instruction . MBL concentration was quantified using an in-house ELISA with mannan coating as previously described . A biotiThe primary outcome of this study was a composite clinical outcome combining in-hospital all-cause mortality and need of intubation and mechanical ventilation, corresponding to a score of 6-8 on the WHO ordinal scale for clinical improvement . SecondaClinical data and laboratory results were collected from the electronic health records and recorded in an electronic database (Research Electronic Data Capture). Patients were followed up for the primary and secondary clinical outcome until death or discharge occurred.Semi-automatic quantification of affected lung tissue on a CT scan was performed using software for lung density analysis in Chest CT . After Statistical analysis was performed using SPSS software, version 25.0 , and GraphPad Prism 7 software was used for visualization . Most of the variables showed skewed distributions and for this reason data are represented as medians with interquartile range (IQR), if not mentioned otherwise. Data from normally distributed variables are presented as means with standard deviation (SD). Nominal data are presented as frequencies (%). Differences between patient groups were assessed using the Mann-Whitney U test for continuous variables, and the chi-square or Fisher’s exact test for nominal variables. Correlations between complement factors and the secondary clinical outcome (LOS) or inflammatory markers were assessed using Spearman rank correlation tests. Multivariable logistic regression models were performed to analyze associations between complement parameters and the composite outcome of mechanical ventilation and/or in-hospital death. Results are presented as odds ratios (OR) with corresponding 95% confidence intervals (CI). Variable selection was based on biologic plausibility and/or demonstrated associations. Differences between groups or correlations were considered statistically significant at the level of p < 0.05 (2-tailed).2], and cardiovascular disease  with a median age of 62 years (IQR 49-73). Frequent comorbidities included arterial hypertension, obesity (body mass index (BMI) ≥30 kg/m disease Table 1.In total, 25 patients (16%) required transfer to the intensive care unit (ICU) during the disease course, 10 (8%) of whom were transferred less than 24 hours after their initial admission to the COVID-19 ward. Death  and/or mechanical ventilation occurred in 23 patients (15%). These patients suffered more frequently from arterial hypertension or obesity, presented with more advanced disease, and were more likely to receive antibiotic, antiviral and anti-inflammatory therapies Table 1.in-vivo activation via the AP and to a lesser degree via the CP of complement. Due to the larger median difference, we explored receiver-operator characteristics analysis of the AP activity to evaluate if a dichotomous cut-off might differentiate between patients with and without the composite outcome . This should be viewed as biological feedback mechanisms in response to activation of several plasmatic cascades including the complement system in an attempt to inhibit or control inappropriate activation , which hOur study did not include a control population of SARS-CoV-2 negative patients with similar disease severity (e.g. influenza). This is an important limitation, as AP activation and consumption and its association with severe SARS-CoV-2 infection and detrimental outcomes may not be specific for COVID-19. In fact, Bain W et al. demonstrated that decreased AP activity was associated with an increased 30-day and one-year mortality in critically ill patients with acute lung injury as a consequence of infectious and non-infectious etiologies . InteresOur study has several additional limitations including the lack of data on other important proteins of the LP  and AP and the single-center design. Importantly, none of our patients was treated with corticosteroids, which were not yet standard of care at the time of inclusion of patients. On the other hand, a significant number of patients was already treated with tocilizumab, a therapy that has shown to improve outcome in moderate to severe COVID-19 , 54. Conin-vivo leading to complement consumption and consequently to a significantly reduced AP activity in-vitro. The LP does not seem to play a role in the progression to severe COVID-19. Apart from its acute phase reaction the significance of C1INH in COVID-19 requires further studies.Our results point to an overactivated AP in critically ill COVID-19 patients The original contributions presented in the study are included in the article/The studies involving human participants were reviewed and approved by Ethics Committee of Northwest and Central Switzerland. Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.MT and MO designed the study. PC, IH, AE, SB, MT, and MO performed the study, collected, analyzed and interpreted the data. PC and MO drafted the manuscript. All authors critically revised the manuscript. All authors contributed to the article and approved the submitted version.Funded by personal and departmental funds MO.MT reports receiving a grant from the Swiss National Science Foundation, and having research collaborations with Roche, Novartis, and Idorsia . MO reports receiving grants from the Swiss National Science foundation outside of the submitted work, and consulting fees from Pharming Technologies B.V. during the conduct of the study and grants from Pharming Biotechnologies B.V. outside the submitted work. AE reports receiving grants from the Swiss National Science foundation outside of the submitted work. No conflict of interest for this work.The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.