Indirect Effects of 10-Valent Pneumococcal Conjugate Vaccine Against Adult Pneumococcal Pneumonia in Rural Western Kenya.
BACKGROUND
Data on pneumococcal conjugate vaccine (PCV) indirect effects in low-income countries with high human immunodeficiency virus (HIV) burden are limited. We examined adult pneumococcal pneumonia incidence before and after PCV introduction in Kenya in 2011.


METHODS
From 1 January 2008 to 31 December 2016, we conducted surveillance for acute respiratory infection (ARI) among ~12 000 adults (≥18 years) in western Kenya, where HIV prevalence is ~17%. ARI cases (cough or difficulty breathing or chest pain, plus temperature ≥38.0°C or oxygen saturation <90%) presenting to a clinic underwent blood culture and pneumococcal urine antigen testing (UAT). We calculated ARI incidence and adjusted for healthcare seeking. The proportion of ARI cases with pneumococcus detected among those with complete testing (blood culture and UAT) was multiplied by adjusted ARI incidence to estimate pneumococcal pneumonia incidence.


RESULTS
Pre-PCV (2008-2010) crude and adjusted ARI incidences were 3.14 and 5.30/100 person-years-observation (pyo), respectively. Among ARI cases, 39.0% (340/872) had both blood culture and UAT; 21.2% (72/340) had pneumococcus detected, yielding a baseline pneumococcal pneumonia incidence of 1.12/100 pyo (95% confidence interval [CI]: 1.0-1.3). In each post-PCV year (2012-2016), the incidence was significantly lower than baseline; with incidence rate ratios (IRRs) of 0.53 (95% CI: 0.31-0.61) in 2012 and 0.13 (95% CI: 0.09-0.17) in 2016. Similar declines were observed in HIV-infected (IRR: 0.13; 95% CI: 0.08-0.22) and HIV-uninfected (IRR: 0.10; 95% CI: 0.05-0.20) adults.


CONCLUSIONS
Adult pneumococcal pneumonia declined in western Kenya following PCV introduction, likely reflecting vaccine indirect effects. Evidence of herd protection is critical for guiding PCV policy decisions in resource-constrained areas.
['Bigogo|Godfrey M|GM|', 'Audi|Allan|A|', 'Auko|Joshua|J|', 'Aol|George O|GO|', 'Ochieng|Benjamin J|BJ|', 'Odiembo|Herine|H|', 'Odoyo|Arthur|A|', 'Widdowson|Marc-Alain|MA|', 'Onyango|Clayton|C|', 'Borgdorff|Martien W|MW|', 'Feikin|Daniel R|DR|', 'Carvalho|Maria da Gloria|MDG|', 'Whitney|Cynthia G|CG|', 'Verani|Jennifer R|JR|']
D000328:Adult D060085:Coinfection D005260:Female D015658:HIV Infections D006801:Humans D015994:Incidence D007630:Kenya D008297:Male D008875:Middle Aged D022242:Pneumococcal Vaccines D011018:Pneumonia, Pneumococcal D062486:Public Health Surveillance D012424:Rural Population D013296:Streptococcus pneumoniae D018074:Vaccines, Conjugate
adult pneumonia Kenya herd immunity pneumococcal vaccines