A test-negative, case-control study revealed that during omicron variant predominance, the estimated vaccine efficacy for two doses of BNT162b2 against symptomatic SARS-CoV-2 infection was moderate and waned rapidly in children and adolescents. However, among adolescents, the estimated vaccine effectiveness increased following the use of booster doses.

Katherine E. Fleming-Dutra et al. aimed to determine the relationship of symptomatic infection with previous vaccination with BNT162b2 to evaluate vaccine effectiveness among adolescents and children. Overall, 43209 negative controls and 30999 positive cases were incorporated from children (5-11 years of age), along with 25 471 negative controls and 22 273 positive cases from adolescents (12-15 years of age).

The median age was 10 years. Notably, 50.2% were females (n= 61 189), 70.1% were White (n= 75 758), and 25.7% were Hispanic/Latino (n= 29 034). At 2 to 4 weeks following administration of 2nd dose in children,  the estimated efficacy of vaccine was 60.1% while the adjusted odds ratio (OR) was 0.40.  In the case of adolescents, the OR was found to be 0.40 and the estimated vaccine effectiveness came out to be 59.5%.

In children, during month 2 following the second dose, the OR was found to be 0.71 (estimated vaccine effectiveness 28.9%) and among adolescents, the OR was 0.83 (estimated vaccine effectiveness 16.6%). The booster dose among adolescents came out to be OR 2 to 6.5 weeks after the dose was 0.29 (estimated vaccine effectiveness 71.1%). Hence, the administration of booster dose was associated with better vaccine effectiveness among adolescents.