Efficacy of anti-SARS-CoV-2 mRNA vaccine in systemic autoimmune disorders: induction of high avidity and neutralising anti-RBD antibodies.
OBJECTIVES
In patients with systemic autoimmune rheumatic disorders (SARDs), vaccination with SARS-CoV-2 mRNA vaccines has been proposed. The aim of this study is to evaluate the immune response elicited by vaccination with mRNA vaccine, testing IgM, IgA and IgG antibodies to SARS-CoV-2 receptor-binding domain (RBD) and measuring neutralising antibodies.


METHODS
IgG, IgM and IgA anti-RBD antibodies were measured in 101 patients with SARDs. Antibodies inhibiting the interaction between RBD and ACE2 were evaluated. Antibody avidity was tested in a chaotropic ELISA using urea. Twenty-one healthcare workers vaccinated with mRNA vaccine served as control group.


RESULTS
Anti-RBD IgG and IgA were produced after the first dose (69% and 64% of the patients) and after the boost (93% and 83%). Antibodies inhibiting the interaction of RBD with ACE2 were detectable in 40% of the patients after the first dose and 87% after boost, compared with 100% in healthy controls (p<0.01). Abatacept and mycophenolate had an impact on the titre of IgG anti-RBD antibodies (p<0.05 and p<0.005, respectively) and on the amount of neutralising antibodies. No effect of other therapies was observed. Vaccinated patients produce high avidity antibodies, as healthy controls.


CONCLUSIONS
These data show that double-dose vaccination induced in patients with SARDs anti-RBD IgG and IgA antibodies in amounts not significantly different from controls, and, most interestingly, characterised by high avidity and endowed with neutralising activity.
['Tani|Chiara|C|0000-0002-0870-8738', 'Pratesi|Federico|F|0000-0002-7226-0907', 'Talarico|Rosaria|R|0000-0003-4268-9611', 'Cardelli|Chiara|C|', 'Caruso|Teresita|T|', 'Di Cianni|Federica|F|', 'Laurino|Elenia|E|', 'Italiano|Nazzareno|N|', 'Moretti|Michele|M|', 'Manca|Maria Laura|ML|', 'Migliorini|Paola|P|', 'Mosca|Marta|M|']
vaccination COVID-19 autoimmune diseases