Pfizer COVID-19 Vaccine Significantly Protected Children, Adolescents During Pandemic


The estimated efficacy of the vaccine against documented infection for children and adolescents during the Omicron wave was 74.3% and 85.5%, respectively.

Pfizer and BioNTech’s mRNA COVID-19 vaccine provided significant protection to children and adolescents during the Delta and Omicron waves of the pandemic, according to new research published in the Annals of Internal Medicine.1

Although COVID-19 mostly causes mild illness in children and adolescents, it can lead to severe disease in some younger patients. Recent research has also found that children and adolescents are at a higher risk of some long COVID symptoms.2 Studies have shown that COVID-19 vaccines are effective in children and adolescents, but most research has had limited follow-up periods.

“Our study has longer follow-up than any previous study, which enabled us to evaluate the real-world, long-term durability of vaccine protection against Delta and Omicron variants,” Yong Chen, an author on the study, said in a release.3 “Further, it covered a diverse representation of US pediatric populations from primary care, specialty care, emergency department, testing centers, and inpatient settings.”

Investigators from the University of Pennsylvania, in collaboration with the Children’s Hospital of Philadelphia, conducted a study to assess the effectiveness of Pfizer and BioNTech’s COVID-19 vaccine in preventing infection and severe disease with different strains of the SARS-CoV-2 virus in previously uninfected children and adolescents. Electronic health record data was gathered from PEDSnet, a national collaboration of pediatric health systems to share data and conduct research.

The study cohort included 77393 adolescents during the Delta wave, of which 45007 were vaccinated, as well as 111539 children and 56080 adolescents during the Omicron wave, of which 50398 and 21180 were vaccinated, respectively. The primary study outcomes were documented infection, illness severity, admission to ICU, and cardiac complications.

Investigators found that the estimated efficacy of the vaccine against documented infection for adolescents during the Delta wave was 98.4%. There also was no statistically significant waning observed after the first dose, and no significant difference of cardiac complications between vaccinated and unvaccinated patients.

The estimated efficacy of the vaccine during the Omicron wave for children was estimated to be 74.3%, with higher levels against moderate or severe disease, and ICU admission. Efficacy for adolescents during Omicron was 85.5% against infection, 84.8% against moderate or severe disease, and 91.5% against ICU admission.

Additionally, there was a lower risk for cardiac complications in the vaccinated group during the Omicron wave.

“Children and adolescents were the last age group to be enrolled in COVID-19 vaccine clinical trials,” Christopher Forrest, an author on the study, said in a release.3 “Although the pandemic has been declared over, the risk of COVID-19 is present throughout US communities. Thus, more information is needed on effectiveness of vaccination delivered to children and adolescents during more recent time periods.”

1. Wu Q, Tong J, Zhang B, et al. Real-World Effectiveness of BNT162b2 Against Infection and Severe Diseases in Children and Adolescents. Ann Intern Med. [Epub 9 January 2024]. doi:10.7326/M23-1754
2. Lopez-Leon S, Wegman-Ostrosky T, Ayuzo del Valle NC, et al. Long-COVID in children and adolescents: a systematic review and meta-analyses. Sci Rep. 12 9950 (2022).
3. Real-world analysis: COVID-19 vaccine is strongly effective for children and adolescents during delta and omicron. News Release. Penn Medicine. January 8, 2024. Accessed January 9, 2024.
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