Fig. 1: Study design and participants.

Cohort 1 consisted of 94 mother–child pairs from The Gambia recruited to a maternal vaccination trial with meningococcal conjugate vaccine. The newborn infants were followed through the first year of life. No microbiological sampling was performed on cohort 1. Cohort 2 comprised participants in the SpyCATS household cohort study. Red text indicates the sampling framework within both cohorts. In cohort 2, participants were swabbed from normal throat and skin to detect carriage. Participants could report disease symptoms (sore throat and skin sores) to the study team, prompting swabbing from the relevant site to detect disease events. Antibodies were measured from serum collected at study baseline and from DBSs at monthly visits and at any disease presentation. Purple boxes represent the number of samples included in each analysis. Breakdown of age groups and event types from cohort 2 is provided. Created in BioRender.com. m, months.