Most children from 5 to 11 years old hospitalized with COVID-19 during the U.S. surge driven by the Omicron variant were unvaccinated, per a Centers for Disease Control and Prevention study published Tuesday.

By the numbers: The study of children hospitalized in the U.S. from Dec. 19 to Feb. 28 found the hospitalization rate was 2.1 times higher for those unvaccinated than their vaccinated peers.

• "Among 397 children hospitalized during the Omicron-predominant period, 87% were unvaccinated, 30% had no underlying medical conditions, and 19% were admitted to an intensive care unit," according to the CDC.

Why it matters: The report not only highlights the effects of vaccines against coronavirus hospitalizations, it also underscores racial disparities in the pandemic.

• Black children accounted for 34% of unvaccinated hospitalizations, compared to 30.7% for white children and 18.9% for Hispanic children, according to the CDC.

Yes, but: The CDC hasn't reported data on the race or ethnicity of vaccinated children in the U.S., which makes it harder for researchers to look into gaps in protection against COVID-19, the New York Times notes.

Worth noting: While Omicron is regarded as less severe than other coronavirus variants, peak intensive care unit admission rates were 1.7 times higher than the period when Delta was dominant in the two-week period ending Oct. 2, according to the study.

What they're saying: "Increasing vaccination coverage among children, particularly among racial and ethnic minority groups disproportionately affected by COVID-19, is critical to preventing COVID-19-associated hospitalization and severe outcomes," the CDC said in its report.

Flashback: A CDC study found last February that unvaccinated people who contracted COVID during the Omicron wave were 23 times more likely to be hospitalized.

Go deeper: Omicron hit little kids hard