Safety Monitoring of Pfizer-BioNTech COVID-19 Vaccine Booster Doses Among Children Aged 5–11 Years

United States, May 17-July 31, 2022

Anne M. Hause, PhD; James Baggs, PhD; Paige Marquez, MSPH; Tanya R. Myers, PhD; John R. Su, MD; Brandon Hugueley, MPH; Deborah Thompson, MD; Julianne Gee, MPH; Tom T. Shimabukuro, MD; David K. Shay, MD


Morbidity and Mortality Weekly Report. 2022;71(33):1047-1051. 

In This Article

Abstract and Introduction


On May 17, 2022, the Food and Drug Administration (FDA) amended the Emergency Use Authorization (EUA) for BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine to authorize a homologous* booster dose for children aged 5–11 years ≥5 months after receipt of the second primary series dose [1] based on findings from a clinical trial conducted among 401 children aged 5–11 years.[2] To further characterize the safety of booster vaccination in this age group, CDC reviewed adverse events and health impact assessments after receipt of a Pfizer-BioNTech third dose reported to v-safe, a voluntary smartphone-based safety surveillance system for adverse events occurring after COVID-19 vaccination, and adverse events reported to the Vaccine Adverse Event Reporting System (VAERS), a passive vaccine safety surveillance system comanaged by CDC and FDA. During May 17–July 31, 2022, approximately 657,302 U.S. children aged 5–11 years received a third Pfizer-BioNTech dose (either a third primary series dose administered to immunocompromised children or a booster dose administered to immunocompetent children)§; 3,249 Pfizer-BioNTech third doses were reported to v-safe for children in this age group. Local and systemic reactions were reported to v-safe after a second dose and a third dose with similar frequency; some reactions (e.g., pain) were reported to be moderate or severe more frequently after a third dose. VAERS received 581 reports of adverse events after receipt of a Pfizer-BioNTech third dose by children aged 5–11 years; 578 (99.5%) reports were considered nonserious, and the most common events reported were vaccine administration errors. Three (0.5%) reports were considered serious; no reports of myocarditis or death were received. Local and systemic reactions were common among children after Pfizer-BioNTech third dose vaccination, but reports of serious adverse events were rare. Initial safety findings are consistent with those of the clinical trial.[2]

V-safe is a voluntary smartphone-based U.S. active safety surveillance system established to monitor adverse events after COVID-19 vaccination ( The v-safe platform allows existing registrants to report receipt of a third COVID-19 vaccine dose and new registrants to enter information about all doses they received. Registrants aged ≤15 years must be enrolled by a parent or guardian. Health surveys are sent daily during the first week after vaccine administration and include questions about potential local injection site and systemic reactions and health impacts. CDC's v-safe call center contacts parents who indicate that medical care was sought for their child after vaccination and encourages completion of a VAERS report, if indicated.

VAERS is a U.S. national passive vaccine safety surveillance system comanaged by CDC and FDA that monitors adverse events after vaccination.[3] VAERS accepts reports from health care providers, vaccine manufacturers, and members of the public.** VAERS reports are classified as serious if any of the following are reported: hospitalization, prolongation of hospitalization, life-threatening illness, permanent disability, congenital anomaly or birth defect, or death.†† VAERS staff members assign Medical Dictionary for Regulatory Activities (MedDRA) preferred terms (PTs) to the signs, symptoms, and diagnostic findings in VAERS reports.§§ CDC and FDA physicians reviewed serious reports to VAERS to form a clinical impression based on available data. Selected MedDRA PTs were used to search for possible cases of myocarditis. Myocarditis and pericarditis are rare adverse events that have been associated with receipt of mRNA-based COVID-19 vaccines, especially among adolescent males and young adults.[4]

This report assessed local and systemic reactions and health impacts reported in the week after vaccination among v-safe registrants aged 5–11 years who received a homologous Pfizer-BioNTech third dose ≥5 months after completion of their primary series during May 17–July 31, 2022. At least one survey after a third and at least one survey after a previous vaccine dose were required for inclusion. The odds of reporting an adverse reaction or health impact after receipt of the third dose and previous doses were compared using multivariable generalized estimating equations models.¶¶ VAERS reports for children aged 5–11 years who received a Pfizer-BioNTech third dose during May 17–July 31, 2022, were described by serious and nonserious classification, demographic characteristics, and MedDRA PTs.*** SAS software (version 9.4; SAS Institute) was used for all analyses. These surveillance activities were reviewed by CDC and conducted consistent with applicable federal law and CDC policy.†††

*Homologous refers to a booster dose of the same product administered for the primary series.
The Advisory Committee on Immunization Practices recommends that all persons aged ≥5 years receive 1 booster dose of a COVID-19 vaccine ≥5 months after completing their primary series with either Pfizer-BioNTech or Moderna mRNA primary series. At the time of publication, only Pfizer-BioNTech vaccine was authorized for use as a booster dose among children aged 5–17 years.
Health surveys for the most recent dose reported are sent via text messages that link to web-based surveys on days 0–7 after receipt of a vaccine dose, then weekly during 6 weeks after vaccination, and then at 3, 6, and 12 months after vaccination. Local injection site reactions include itching, pain, redness, and swelling. Systemic reactions include abdominal pain, myalgia, chills, diarrhea, fatigue, fever, headache, joint pain, nausea, rash, and vomiting. Health impacts include inability to perform normal daily activities, inability to attend school, and receipt of medical care. Parents and guardians use the following definitions to describe the severity of a child's symptoms: mild (noticeable, but not problematic), moderate (limit normal daily activities), or severe (make daily activities difficult or impossible).
**CDC and FDA encourage health care providers to report adverse events to VAERS, and providers are required by COVID-19 vaccine EUAs to report certain adverse events, including death, after vaccination to VAERS.
††VAERS reports are classified as serious based on 21 C.F.R.
§§Each VAERS report might be assigned more than one MedDRA PT. A MedDRA-coded event does not indicate a medically confirmed diagnosis.
¶¶This model accounted for repeated measures among doses reported by each registrant. The threshold for statistical significance was p<0.05.
***This analysis excluded reports to v-safe or VAERS of children aged 5–11 years who were vaccinated with a booster dose before authorization for a booster dose for their age group (i.e., before May 17, 2022).
†††45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. Sect. 241(d); 5 U.S.C. Sect. 552a; 44 U.S.C. Sect. 3501 et seq.