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Real-World Effectiveness of BNT162b2 Against Infection and Severe Diseases in Children and Adolescents
Qiong Wu1, Jiayi Tong1, Bingyu Zhang2
1The Center for Health Analytics and Synthesis of Evidence (CHASE), Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania (Q.W., J.T., D.Z., J.C., Y.Lei, Y.W.).
Insights
The BNT162b2 vaccine effectively protected children and adolescents against COVID-19 during the Delta and Omicron variants. Vaccine effectiveness showed some waning over time, particularly against Omicron infections.
Area of Science:
- Pediatric infectious diseases
- Vaccinology
- Public health
Background:
- The BNT162b2 vaccine's pediatric efficacy was established before the Omicron variant.
- Long-term protection durability in children during the Omicron era requires further assessment.
Purpose of the Study:
- To evaluate the effectiveness of the BNT162b2 vaccine in preventing SARS-CoV-2 infection and severe disease in children and adolescents.
- To analyze vaccine performance against different COVID-19 strains, including Delta and Omicron variants.
Main Methods:
- A comparative effectiveness study utilized data from a national collaboration of pediatric health systems (PEDSnet).
- The study included adolescents during the Delta phase and children and adolescents during the Omicron phase.
- Propensity score stratification balanced confounders for comparing vaccinated individuals with unvaccinated controls.
Main Results:
- During the Delta phase, BNT162b2 vaccine effectiveness against infection in adolescents was 98.4%.
- In the Omicron phase, effectiveness against infection was 74.3% in children and 85.5% in adolescents.
- Effectiveness waned approximately 4 months post-vaccination but stabilized, with lower cardiac complication risks observed in vaccinated groups during the Omicron period.
Conclusions:
- The BNT162b2 vaccine demonstrated significant effectiveness against COVID-19 outcomes in pediatric populations during both Delta and Omicron variant periods.
- Evidence suggests a decline in vaccine effectiveness over time, highlighting the need for ongoing monitoring and potential booster strategies.
Background:
The 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.
Objective:
To 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.
Design:
Comparative effectiveness research accounting for underreported vaccination in 3 study cohorts: adolescents (12 to 20 years) during the Delta phase and children (5 to 11 years) and adolescents (12 to 20 years) during the Omicron phase.
Setting:
A national collaboration of pediatric health systems (PEDSnet).
Participants:
77 392 adolescents (45 007 vaccinated) during the Delta phase and 111 539 children (50 398 vaccinated) and 56 080 adolescents (21 180 vaccinated) during the Omicron phase.
Intervention:
First dose of the BNT162b2 vaccine versus no receipt of COVID-19 vaccine.
Measurements:
Outcomes 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.
Results:
During the Delta period, the estimated effectiveness of the BNT162b2 vaccine was 98.4% (95% CI, 98.1% to 98.7%) against documented infection among adolescents, with no statistically significant waning after receipt of the first dose. An analysis of cardiac complications did not suggest a statistically significant difference between vaccinated and unvaccinated groups. During the Omicron period, the effectiveness against documented infection among children was estimated to be 74.3% (CI, 72.2% to 76.2%). Higher levels of effectiveness were seen against moderate or severe COVID-19 (75.5% [CI, 69.0% to 81.0%]) and ICU admission with COVID-19 (84.9% [CI, 64.8% to 93.5%]). Among adolescents, the effectiveness against documented Omicron infection was 85.5% (CI, 83.8% to 87.1%), with 84.8% (CI, 77.3% to 89.9%) against moderate or severe COVID-19, and 91.5% (CI, 69.5% to 97.6%) against ICU admission with COVID-19. The effectiveness of the BNT162b2 vaccine against the Omicron variant declined 4 months after the first dose and then stabilized. The analysis showed a lower risk for cardiac complications in the vaccinated group during the Omicron variant period.
Limitation:
Observational study design and potentially undocumented infection.
Conclusion:
This 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 Source:
National Institutes of Health.
