BOSTON, Mass. — Many young children are still waiting for the green light to receive a COVID vaccine, however, a new study has encouraging news for those who are eligible. Researchers from Boston Children’s Hospital found that vaccinated children between the ages of five and 11 have a much lower risk of ending up in the hospital due to the Omicron variant.
Compared to Delta, the newer Omicron strain has more than double the number of mutations that make it more infectious. During the winter surge of 2021-22, Omicron overtook Delta as the most prevalent variant in the United States. It is also responsible for an unprecedented increase in pediatric hospitalizations. Despite the growing threat of infection, only 27 percent of children had received two COVID-19 vaccine doses as of March 16.
“The reason for a child to get a COVID-19 vaccine is to prevent severe complications of SARS-CoV-2 infection, including hospitalization,” says Adrienne Randolph, MD, MSc, a researcher at Boston Children’s Hospital and the Centers for Disease Control and Prevention, in a media release. “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.”

Vaccines keeping breakthrough cases from becoming severe
In 2020, Dr. Randolph launched a program called Overcoming COVID-19 Network that would collect data on children hospitalized for COVID-19 infection. It includes 1,185 children with COVID-19 at 31 pediatric hospitals across the U.S., 918 adolescents between 12 and 18, and 267 children from five to 11. The control group included patients of similar ages hospitalized for non-COVID reasons.
The researchers analyzed data between July 2021 and Feb. 17, 2022, which were the times when Delta and Omicron spread like wildfire. However, they could only study vaccine effectiveness towards the Omicron variant since the vaccine was not approved for children until October 2021.
Overall, 88 percent of hospitalized children with COVID-19 infection were unvaccinated. Of these, one-quarter were in critical condition and required life-supporting treatment. When looking at children by age group, 92 percent of hospitalized kids between ages five and 11 were unvaccinated. Of the 16 percent of kids needing intubation while in the hospital, 90 percent were unvaccinated.
Children between five and 11 who received two doses of the Pfizer-BioNTech COVID-19 vaccine were 68 percent less likely to need hospitalization due to Omicron.
Among adolescents between 12 and 18 years-old, two vaccines provided 92 percent protection against hospitalization against Delta. With Omicron, vaccine protection fell to 40 percent. However, teens still had 79 percent effectiveness against severe Omicron infection.
“We hope our findings will help parents make the decision to vaccinate their children and teens against COVID-19,” says Dr. Randolph. “The benefits clearly outweigh the risks, as severe infections in childhood can have long-term consequences.”
The study is published in The New England Journal of Medicine.