Schematic of study schedule for children in the MARkers of Vaccine Efficacy and Longevity in SARS-CoV-2 (MARVELS) study up to 6 months after vaccination, as well as a flowchart of individuals between 6 and 12 months, divided into children with vaccine-only immunity at 6 months (n = 34) and children with hybrid immunity at 6 months (n = 76). Children were given two doses of monovalent 10 g BNT162b2 on day 0 and day 21 of the study. Venous blood was drawn at pre-vaccination baseline, day 10 after dose one, 3 months after vaccination and 6 months after vaccination. A mirror cohort of healthy adult healthcare workers, who were given two doses of monovalent 30 g BNT162b2, was used as the reference for immunogenicity parameters. Convenience sampling was used for adults, with 18 to 20 individuals per immunogenicity comparison. Children who acquired natural SARS-CoV-2 infection, both symptomatic and asymptomatic, were excluded from comparison to adults.
