Effectiveness of BNT162b2 vaccine against symptomatic SARS-CoV-2 infection in children aged 5-11 years in Japan during Omicron variant predominate periods.

Two BNT162b messenger RNA vaccine doses provided moderate protection against symptomatic COVID-19 during the Omicron variant period. A time-dependent decrease in VE was noted after the second dose; thus, a booster dose 3 months after the second dose is warranted.