Data regarding the real-world effectiveness of the BNT162b2 vaccine against coronavirus disease 2019 (Covid-19) and specifically against infection with the omicron variant among children 5 to 11 years of age are scarce.

A recent study identified a cohort of children aged 5-11 years who were vaccinated on or after November 23, 2021, and matched them with unvaccinated controls to evaluate the vaccine effectiveness of BNT162b2 among newly vaccinated children during the omicron wave. It estimated the effectiveness of the vaccine against documented severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and symptomatic Covid-19, after the first and second vaccine doses.

The results were as follows-

• 136,127 children were vaccinated and eligible for the study, among which 94,728 were matched with unvaccinated controls.
• The vaccine effectiveness against documented infection was estimated to be 17% at 14-27 days after the first dose and 51% at 7-21 days after the second dose.
• The absolute risk difference between the study groups on days 7 to 21 after the second dose was found to be 1905 events/100,000 persons for documented infection and 599 events/100,000 persons for symptomatic Covid-19.
• The estimated vaccine effectiveness against symptomatic Covid-19 was found to be 18% at 14 to 27 days after the first dose and 48% at 7 to 21 days after the second dose.
• A trend was observed toward higher vaccine effectiveness in the youngest age group (5 or 6 years of age) than in the oldest age group (10 or 11 years of age).

Thus, during the emergence of omicron as the dominant variant, two doses of the BNT162b2 messenger RNA vaccine furnished moderate protection against documented SARS-CoV-2 infection and symptomatic Covid-19 in children 5 to 11 years of age. 

Cohen-Stavi CJ, Magen O, Barda N., et al. BNT162b2 Vaccine Effectiveness against Omicron in Children 5 to 11 Years of Age. N Engl J Med 2022; 387:227-236. DOI: 10.1056/NEJMoa2205011