U.S. states with low vaccination rates see sharp spikes in children with Covid-19.

The number of children admitted to the hospital in the United States with Covid-19 has risen to the highest levels reported to date. Nearly 30,000 of them entered hospitals in August.

Pediatric hospitalizations, driven by a record rise in coronavirus infections among children, have swelled, overwhelming children’s hospitals and intensive care units in states like Louisiana and Texas. During the summer surge, the hospitalization rate was about 10 times as high in unvaccinated adolescents as in those who were vaccinated, according to a recent federal study. Data on hospitalizations among children of different ages is limited.

Children remain markedly less likely than adults to be hospitalized or die from Covid-19. But the United States recorded more than 250,000 child virus cases in the past week, the highest number to date, according to the most recent American Academy of Pediatrics survey of state data.

“It should concern us all that hospitalizations — indicators of severe illness — are rising in the pediatric population, when there are a lot of steps we could take to prevent many of these hospitalizations,” said Jason L. Salemi, an epidemiologist at the University of South Florida, who tracks Covid-19 hospitalization data.

According to Dr. Christopher Carroll, a pediatric intensivist at Connecticut Children’s Medical Center, the average U.S. pediatric I.C.U. in the U.S. has 12 beds. “In a system that small, even a few patients can quickly overrun the capacity, ” he said. “And there are fewer specialty trained pediatric clinicians to pick up the slack.”

Experts have said that vaccinations can make all the difference. States with the highest vaccination rates in the country have seen relatively flat pediatric hospital admissions for Covid-19 so far, while states with the lowest vaccine coverage have child hospital admissions that are around four times as high.