Top 5 Takeaways

1. Vaccine Effectiveness: Two doses of the Pfizer-BioNTech COVID-19 vaccine reduced the risk of Omicron infection by 31% among children aged 5–11 years and by 59% among adolescents aged 12–15 years.
2. Asymptomatic Infections: Approximately half of Omicron infections in unvaccinated children and adolescents were asymptomatic.
3. Symptom Duration: Vaccinated participants with Omicron infections spent an average of one half day less sick in bed compared to unvaccinated participants.
4. Mask Usage: Vaccinated participants reported wearing masks more frequently than unvaccinated participants, both in school and in the community.
5. Public Health Recommendation: All eligible children and adolescents should remain up to date with recommended COVID-19 vaccinations.

Original Article Author and Citation

Corresponding Author

Ashley L. Fowlkes, ahl4@cdc.gov

Suggested Citation

Fowlkes AL, Yoon SK, Lutrick K, et al. Effectiveness of 2-Dose BNT162b2 (Pfizer BioNTech) mRNA Vaccine in Preventing SARS-CoV-2 Infection Among Children Aged 5–11 Years and Adolescents Aged 12–15 Years — PROTECT Cohort, July 2021–February 2022. MMWR Morb Mortal Wkly Rep 2022;71:422–428. DOI: http://dx.doi.org/10.15585/mmwr.mm7111e1

Summary

This study evaluated the effectiveness of two doses of the Pfizer-BioNTech COVID-19 vaccine in preventing SARS-CoV-2 infection among children aged 5–11 years and adolescents aged 12–15 years from July 2021 to February 2022. The study found that the vaccine reduced the risk of Omicron infection by 31% in children and by 59% in adolescents. Additionally, vaccinated participants had a shorter duration of illness compared to unvaccinated participants.

Methods

The PROTECT cohort study monitored SARS-CoV-2 infections among 1,364 children and adolescents aged 5–15 years across four states (Arizona, Florida, Texas, and Utah). Participants were tested weekly for SARS-CoV-2, irrespective of symptoms, and upon COVID-19–associated illness. Vaccination status was verified through vaccine cards, electronic medical records, and state immunization registries. Data were analyzed using Cox proportional hazards models and SAS or R software.

Discussion

The study found that two doses of the Pfizer-BioNTech vaccine were effective in preventing both symptomatic and asymptomatic SARS-CoV-2 infections, with varying effectiveness by variant. The vaccine was more effective against the Delta variant compared to the Omicron variant. The findings also highlighted the importance of mask usage, with vaccinated participants reporting higher mask usage rates than unvaccinated participants.

Conclusion

The study provides evidence supporting the effectiveness of two doses of the Pfizer-BioNTech vaccine in preventing SARS-CoV-2 infections among children and adolescents. It underscores the importance of keeping up to date with recommended COVID-19 vaccinations for all eligible children and adolescents.

This has been your booster shot of MMWR Info! Please check back for more MMWR, Public Health, and Programming Tutorial content daily.