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

Ashley L. Fowlkes, Sarang K. Yoon, Karen Lutrick, Lisa Gwynn, Joy Burns, Lauren Grant, Andrew L. Phillips, Katherine Ellingson, Maria V. Ferraris, Lindsay B. LeClair, Clare Mathenge, Young M. Yoo, Matthew S. Thiese, Lynn B. Gerald, Natasha Schaefer Solle, Zuha Jeddy, Leah Odame-Bamfo, Josephine Mak, Kurt T. Hegmann, Joe K. GeraldJezahel S. Ochoa, Mark Berry, Spencer Rose, Julie Mayo Lamberte, Purnima Madhivanan, Felipe A. Pubillones, Ramona P. Rai, Kayan Dunnigan, John T. Jones, Karl Krupp, Laura J. Edwards, Edward J. Bedrick, Brian E. Sokol, Ashley Lowe, Hilary McLeland-Wieser, Krystal S. Jovel, Deanna E. Fleary, Sana M. Khan, Brandon Poe, James Hollister, Joanna Lopez, Patrick Rivers, Shawn Beitel, Harmony L. Tyner, Allison L. Naleway, Lauren E.W. Olsho, Alberto J. Caban-Martinez, Jefferey L. Burgess, Mark G. Thompson, Manjusha Gaglani

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


The BNT162b2 (Pfizer-BioNTech) mRNA COVID-19 vaccine was recommended by CDC’s Advisory Committee on Immunization Practices for persons aged 12–15 years (referred to as adolescents in this report) on May 12, 2021, and for children aged 5–11 years on November 2, 2021 (1–4). Realworld data on vaccine effectiveness (VE) in these age groups are needed, especially because when the B.1.1.529 (Omicron) variant became predominant in the United States in December 2021, early investigations of VE demonstrated a decline in protection against symptomatic infection for adolescents aged 12–15 years and adults* (5). The PROTECT† prospective cohort of 1,364 children and adolescents aged 5–15 years was tested weekly for SARS-CoV-2, irrespective of symptoms, and upon COVID-19–associated illness during July 25, 2021–February 12, 2022. Among unvaccinated participants (i.e., those who had received no COVID-19 vaccine doses) with any laboratory-confirmed SARS-CoV-2 infection, those with B.1.617.2 (Delta) variant infections were more likely to report COVID-19 symptoms (66%) than were those with Omicron infections (49%). Among fully vaccinated children aged 5–11 years, VE against any symptomatic and asymptomatic Omicron infection 14–82 days (the longest interval after dose 2 in this age group) after receipt of dose 2 of the Pfizer-BioNTech vaccine was 31% (95% CI = 9%–48%), adjusted for sociodemographic characteristics, health information, frequency of social contact, mask use, location, and local virus circulation. Among adolescents aged 12–15 years, adjusted VE 14–149 days after dose 2 was 87% (95% CI = 49%–97%) against symptomatic and asymptomatic Delta infection and 59% (95% CI = 22%–79%) against Omicron infection. Fully vaccinated participants with Omicron infection spent an average of one half day less sick in bed than did unvaccinated participants with Omicron infection. All eligible children and adolescents should remain up to date with recommended COVID-19 vaccinations.

Original languageEnglish (US)
Pages (from-to)422-428
Number of pages7
JournalMMWR Recommendations and Reports
Issue number11
StatePublished - 2022

ASJC Scopus subject areas

  • Epidemiology
  • Health(social science)
  • Health, Toxicology and Mutagenesis
  • Health Information Management


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