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. 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. Read more.