About 87% of children hospitalized with Covid-19 when the omicron variant was dominant were unvaccinated, according to a study released Tuesday by the Centers for Disease Control and Prevention, offering a stark reminder of the risks of leaving children unvaccinated.

KEY FACTS

From mid-December to late February, unvaccinated children ages 5 to 11 had a hospitalization rate 2.1 times higher than their vaccinated peers, according to a study of 1,475 children conducted by researchers affiliated with the CDC and other public health and research institutions.

Unvaccinated children also spent longer in the hospital, with a mean hospitalization length of three days, compared to two days for vaccinated children hospitalized with the coronavirus.

Black children accounted for 34% of unvaccinated hospitalizations, compared to 30.7% for white children and 18.9% for Hispanic children, reflecting lower vaccination rates among Black Americans.

Though children with diabetes and obesity were more likely to develop severe Covid-19, 30% of hospitalized children had no underlying medical conditions, researchers said.

KEY BACKGROUND

The Food and Drug Administration has authorized Pfizer and BioNTech’s Covid-19 vaccine for kids age 5 and older. Though an FDA-endorsed study found that Pfizer’s vaccine was 90.7% effective at preventing Covid-19 among children in that age range and caused no serious side effects, younger Americans remain less likely to be vaccinated or boosted than older people. The omicron variant has been linked to a fourfold increase in child Covid-19 hospitalizations, as well as an increase in potentially severe symptoms such as upper airway infections, which can trigger heart attacks. Scientists have struggled to explain why a generally less severe form of the coronavirus would lead to more hospitalizations among children. One possible explanation is that children are more vulnerable to omicron because they are less likely to have acquired resistance through previous infection or through vaccination—a theory the CDC’s new research appears to support. Tuesday’s CDC study reinforced previous findings that vaccination protects children against potentially life-threatening Covid-19 complications like multisystem inflammatory syndrome, researchers said.

BIG NUMBER

12.9 million. That’s the cumulative number of child Covid-19 cases reported in the U.S. as of Thursday, accounting for 19% of all cases, according to the American Academy of Pediatrics (AAP). An AAP study of data from 46 states, New York City, Puerto Rico and Guam found a cumulative total of 994 child Covid-19 deaths.

CONTRA

Omicron appears to put children at less risk of severe illness than other coronavirus variants. Between December 26 and February 17, the risk of severe illness among children hospitalized with Covid-19 fell to 3.4%, down from 38.8% during the previous roughly 22 months, according to the JAMA Pediatrics study. An AAP analysis of data from 46 states found that children accounted for between 0% and 0.26% of Covid-19 deaths in each state, with three states reporting zero child Covid-19 deaths. Tuesday’s CDC study recorded no child deaths during either the delta period of the omicron period.