Covid-19 hospitalization rates among children increased as Omicron replaced Delta as the predominant coronavirus variant in the United States, especially among those under 5, who are not eligible to be vaccinated, according to a study published Tuesday by the US Centers for Disease Control and Prevention.
At their peak, weekly pediatric Covid-19 hospitalization rates were four times higher during a period of Omicron dominance than during a period of Delta dominance. Children younger than 5 saw the largest increase, with hospitalization rates that were more than five times higher during Omicron than during Delta.
There had been hope that a coronavirus vaccine for children younger than 5 would be available in late February or early March, after Pfizer and BioNTech requested US Food and Drug Administration emergency use authorization of a two-dose series of their child-sized vaccine for children 6 months through 4 years old.
But on Friday, the FDA said it would wait for the vaccine makers to submit data from an ongoing trial on a three-dose regimen in these younger children before moving forward. The data is expected to be available in April.
The new study found that the share of pediatric patients admitted to a hospital primarily for Covid-19 was consistent during both the Delta and Omicron periods, suggesting that “incidental admissions do not account for the increase in hospitalization rates observed during the Omicron period,” according to the study.
In December, when both variants were circulating, hospitalization rates were six times higher among unvaccinated adolescents ages 12 to 17 than they were among fully vaccinated adolescents. Hospitalization rates by vaccination status were not analyzed for other age groups that were not eligible to be vaccinated throughout the full time period studied.
During periods of both Delta and Omicron prevalence from July through December, unvaccinated adolescents were twice as likely to be admitted to the ICU than those who were vaccinated; about 30% of unvaccinated patients were admitted to the ICU, compared with 15.5% of vaccinated adolescents.
Overall, children and adolescents were less likely to be admitted to the ICU or require ventilation during Omicron than they were during Delta.
“Vaccination of eligible persons, in addition to other prevention strategies such as masking, are critical to reducing the incidence of severe Covid-19 among children and adolescents,” the authors of the study wrote.
“All persons who are eligible for vaccination should receive and stay up to date with COVID-19 vaccines to reduce the risk for severe disease for themselves and others with whom they come into contact, including children who are currently too young to be vaccinated.”
Children 5 and older are eligible to be vaccinated with the Pfizer/BioNTech Covid-19 vaccine. People 12 and older are also eligible for Pfizer booster shots. Children younger than 5 are not eligible to be vaccinated against Covid-19.
In the US, vaccination rates among children lag significantly behind those of adults. Less than a quarter (24%) of children ages 5 to 11 and 57% of adolescents ages 12 to 17 are fully vaccinated, compared with about three-quarters (75%) of adults, according to CDC data.
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The authors of the study also highlight the importance of addressing racial and ethnic disparities in vaccination. More than 42% of unvaccinated adolescents who were hospitalized with Covid-19 were Black.
For this study, data from about 2,000 pediatric hospitalizations captured by the CDC’s Covid-19 Associated Hospitalization Surveillance Network (COVID-NET) were analyzed. A period of Delta prevalence captured hospitalizations between July and mid-December, and a period of Omicron prevalence captured the second half of December. The Omicron surge peaked after the period of this study.