Fig. 1From: The transfer of maternal antibodies and dynamics of maternal and natural infection-induced antibodies against coxsackievirus A16 in Chinese children 0–13 years of age: a longitudinal cohort studyRecruitment and follow-up rates for the two cohorts. #Residual serum samples from 538 participants were available at baseline, while quantities of sera from one participant at 2 months of age were insufficient for the CVA16 neutralization test. £Details of the selection are described in the appendix (Additional file 1: Table S1). §A subgroup of children (25%, 609/2475) in the paediatric cohort attended semiannual follow-up in addition to the routine annual follow-upBack to article page