THURSDAY, March 31, 2022 (HealthDay News) -- The Pfizer COVID vaccine significantly reduced U.S. children's risk of severe illness and hospitalization during the recent Omicron surge, according to a new study.
But researchers noted that only 27% of 5- to 11-year-olds in the United States and just 57% of 12- to 17-year-olds had received two vaccine doses as of March 16, and said they hoped their findings would help persuade reluctant parents to get their kids vaccinated.
"The reason for a child to get a COVID-19 vaccine is to prevent severe complications of SARS-CoV-2 infection, including hospitalization," said study co-leader Dr. Adrienne Randolph, of Boston Children's Hospital and the U.S. Centers for Disease Control and Prevention.
The Pfizer vaccine became available in the United States in December 2020 for people 16 or older; for 12- to 15-year-olds in May 2021; and for 5- to 11-year-olds in October 2021.
For the new study, Randolph's team analyzed data on 267 children aged 5 to 11 years, and 918 kids aged 12 to 18 hospitalized with COVID-19 between July 2021 and Feb. 17, 2022.
Overall, 88% were unvaccinated and 25% were critically ill and required life support measures such as intubation.
Among 5- to 11-year-olds, 92% were unvaccinated and 16% were critically ill. Of those who were critically ill, 90% were unvaccinated, the researchers said.
Among 12- to 18-year-olds, 87% were unvaccinated and 27% were critically ill. Of those who were critically ill, 93% were unvaccinated. Two patients in this age group died, according to the report.
Based on this data, the study authors calculated that two doses of the Pfizer vaccine were 68% effective in preventing hospitalization among children between 5 and 11 years of age during the Omicron surge.
Because children in this age group only became eligible for the vaccine in October, there weren't sufficient numbers to evaluate its impact on the risk of critical illness during the Omicron surge, or how it affected the risk of hospitalization and critical illness during the Delta surge that preceded it, the researchers explained.
Among 12- to 18-year-olds, two doses of the Pfizer vaccine were 92% effective against hospitalization during the Delta surge, and 40% effective during the Omicron wave.
In this age group, vaccination was 96% effective in preventing critical illness during Delta and 79% effective during the Omicron surge, according to the report published March 30 in the New England Journal of Medicine.
"This evidence shows that vaccination reduces this risk substantially in 5- to 11-year-olds. And while vaccination provided adolescents with lower protection against hospitalization with Omicron versus Delta, it prevented critical illness from both variants," Randolph said in a hospital news release.
Randolph said she hopes parents will get their kids and teens vaccinated. A highly contagious Omicron subvariant called BA.2 is now the dominant cause of COVID-19 in the United States.
The new study shows that even vaccines targeted at the original variant of SARS-CoV-2 "are extremely effective at preventing critical illness," said Dr. Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security, in Baltimore. "These findings highlight the power of the vaccines to shift COVID-19 to a milder spectrum of illness."
For more on COVID-19 vaccines and children, go to the American Academy of Pediatrics.
SOURCES: Boston Children's Hospital, news release, March 30, 2022; Amesh Adalja, MD, senior scholar, Johns Hopkins Center for Health Security, Baltimore