Real-world Effectiveness of BNT162b2 Against Infection and Severe Diseases in Children and Adolescents
Authors: Wu Qiong , Tong Jiayi , Zhang Bingyu , Zhang Dazheng , Chen Jiajie , Lei Yuqing , Lu Yiwen , Wang Yudong , Li Lu , Shen Yishan , Xu Jie , Bailey L. Charles , Bian Jiang , Christakis Dimitri A. , Fitzgerald Megan L. , Hirabayashi Kathryn , Jhaveri Ravi , Khaitan Alka , Lyu Tianchen , Rao Suchitra , Razzaghi Hanieh , Schwenk Hayden T. , Wang Fei , Witvliet Margot I. , Tchetgen Tchetgen Eric J. , Morris Jeffrey S. , Forrest Christopher B. , Chen Yong 
Published: June 2023

ABSTRACTBackgroundThe efficacy of the BNT162b2 vaccine in pediatrics was assessed by randomized trials before the Omicron variant’s emergence. The long-term durability of vaccine protection in this population during the Omicron period remains limited.ObjectiveTo assess the effectiveness of BNT162b2 in preventing infection and severe diseases with various strains of the SARS-CoV-2 virus in previously uninfected children and adolescents.DesignComparative effectiveness research accounting for underreported vaccination in three study cohorts: adolescents (12 to 20 years) during the Delta phase, children (5 to 11 years) and adolescents (12 to 20 years) during the Omicron phase.SettingA national collaboration of pediatric health systems (PEDSnet).Participants77,392 adolescents (45,007 vaccinated) in the Delta phase, 111,539 children (50,398 vaccinated) and 56,080 adolescents (21,180 vaccinated) in the Omicron period.ExposuresFirst dose of the BNT162b2 vaccine vs. no receipt of COVID-19 vaccine.MeasurementsOutcomes of interest include documented infection, COVID-19 illness severity, admission to an intensive care unit (ICU), and cardiac complications. The effectiveness was reported as (1-relative risk)*100% with confounders balanced via propensity score stratification.ResultsDuring the Delta period, the estimated effectiveness of BNT162b2 vaccine was 98.4% (95% CI, 98.1 to 98.7) against documented infection among adolescents, with no significant waning after receipt of the first dose. An analysis of cardiac complications did not find an increased risk after vaccination. During the Omicron period, the effectiveness against documented infection among children was estimated to be 74.3% (95% CI, 72.2 to 76.2). Higher levels of effectiveness were observed against moderate or severe COVID-19 (75.5%, 95% CI, 69.0 to 81.0) and ICU admission with COVID-19 (84.9%, 95% CI, 64.8 to 93.5). Among adolescents, the effectiveness against documented Omicron infection was 85.5% (95% CI, 83.8 to 87.1), with 84.8% (95% CI, 77.3 to 89.9) against moderate or severe COVID-19, and 91.5% (95% CI, 69.5 to 97.6)) against ICU admission with COVID-19. The effectiveness of the BNT162b2 vaccine against the Omicron variant declined after 4 months following the first dose and then stabilized. The analysis revealed a lower risk of cardiac complications in the vaccinated group during the Omicron variant period.LimitationsObservational study design and potentially undocumented infection.ConclusionsOur study suggests that BNT162b2 was effective for various COVID-19-related outcomes in children and adolescents during the Delta and Omicron periods, and there is some evidence of waning effectiveness over time.Primary Funding SourceNational Institutes of Health