The Pfizer-BioNTech COVID-19 vaccine has been a moderately effective tool for preventing the spread of COVID-19 and reducing the severity of infection among children and adolescents, a new study shows.
Researchers tested a total of 1,364 children ages 5-15 for SARS-CoV-2, the virus that causes COVID-19, weekly from July 25, 2021, to February 12, 2022. The findings showed that vaccination with two doses of the Pfizer-BioNTech COVID-19 vaccine reduced the risk of infection with the Omicron variant by 31% in children ages 5-11 and by 59% in adolescents ages 12-15.
The report showed declining protection in adolescents when comparing the Omicron and Delta periods, as vaccination was 87% effective at preventing infections among adolescents ages 12-15 years when the Delta variant was the dominant strain circulating in the US.
The Pfizer-BioNTech mRNA COVID-19 vaccine was recommended by the Center for Disease Control and Prevention’s Advisory Committee on Immunization Practices for adolescents ages 12-15 on May 12, 2021, and children ages 5-11 years on November 2, 2021.
Researchers say the findings, published today in the CDC’s Morbidity and Mortality Weekly Report (MMWR), provide some evidence that all children and adolescents should remain up to date with recommended COVID-19 vaccinations.
The ongoing PROTECT study is among the largest studies with routine weekly COVID-19 testing, regardless of COVID-19-like symptoms. The study, initiated in July 2021, monitors SARS-CoV-2 infections among participants aged 6 months to 17 years in jurisdictions in four states: Arizona, Florida, Texas, and Utah.
PROTECT data includes University of Arizona Health Sciences research from the Arizona Healthcare, Emergency Response, and Other Essential Workers Surveillance study, or AZ HEROES study, which the CDC has funded since spring 2020.
“We are so appreciative that parents in our study are taking the time to test their kids weekly and provide us with this vital data,” says Karen Lutrick, assistant professor in the University of Arizona College of Medicine-Tucson’s family and community medicine department and third author on the MMWR report.
“Our findings inform science-based vaccine guidance. This shows the community support for research and the CDC’s effort to provide the best public health recommendations possible.”
Researchers also evaluated the severity of COVID-19 illness among unvaccinated children and adolescents infected during periods of Delta and Omicron circulation and found that Omicron infections were less severe than Delta infections. Among unvaccinated infected children, children with Omicron infections were less likely to report COVID-19 symptoms (49%) than children with Delta infections (66%).
Symptomatic Omicron infection among children and adolescents—both vaccinated and unvaccinated—resulted in an average of 5-6 days of symptoms and 1-2 days in bed.
The data also allowed researchers to gain a better understanding the factors that can affect infection risk within this age group, including socio-demographic characteristics, health information, frequency of close social contact, mask use, location, and local virus circulation.
Source: Shipherd Reed for University of Arizona