Streptococcus pyogenescolonization in children aged 24-59 months in The Gambia: Impact of Live Attenuated Influenza Vaccine and associated serological responses

Abstract

AbstractBackgroundImmunity toStreptococcus pyogenesin high burden settings is poorly understood. We exploredS. pyogenesnasopharyngeal colonization after intranasal live attenuated influenza vaccine (LAIV) among Gambian children aged 24-59 months, and resulting serological response to 7 antigens.MethodsA post-hoc analysis was performed in 320 children randomized to receive LAIV at baseline (LAIV group) or not (control).S. pyogenescolonization was determined by quantitative Polymerase Chain Reaction (qPCR) on nasopharyngeal swabs from baseline (D0), day 7 (D7) and day 21 (D21). Anti-streptococcal IgG was quantified, including a subset with paired serum pre/postS. pyogenesacquisition.ResultsThe point prevalence ofS. pyogenescolonization ranged from 7-13%. In children negative at D0,S. pyogeneswas detected at D7 or D21 in 18% of LAIV group and 11% of control group participants (p=0.12). The odds ratio (OR) for colonization over time was significantly increased in the LAIV group (D21 vs D0 OR 3.18, p=0.003) but not in the control group (OR 0.86, p=0.79). The highest IgG increases following asymptomatic colonization were seen for M1 and SpyCEP proteins.ConclusionsAsymptomaticS. pyogenescolonization appears modestly increased by LAIV, and may be immunologically significant. LAIV could be used to study influenza-S. pyogenesinteractions.