According to recent numbers from the Centers for Disease Control and Prevention, the ongoing spread of the Omicron variant of COVID-19 has lead to a massive spike in child hospitalizations. In the seven-day period from Dec. 21 to Dec. 27, 334 American children went to hospital. That’s a 58% increase compared to the previous week, compared to a more modest 19% increase in the general population.

“Certainly, more children are being infected with the highly transmissible virus, and with that, there naturally will be more hospitalizations in children,” Dr. Anthony Fauci said at Wednesday’s White House COVID-19 Response Team briefing. “The final conclusion about the level of severity in children remains to be determined.”

The spike in child COVID-19 hospitalizations can be felt strongly in New York City, currently dealing with one of the largest Omicron-fueled outbreaks in the country. In the week of Dec. 5, 22 New York City children went to the hospital. That number was up to 109 between Dec. 19 and Dec. 23.

Child COVID-19 hospitalizations are spiking in other parts of the country, as well. The Ohio Hospital Association tracked a 125% increase in hospitalizations among children 17 and under in the past four weeks. The CDC reported child COVID-19 hospitalizations have doubled in Florida, New Jersey and Illinois over the last week.

The spike may place a greater emphasis on child vaccinations and COVID-19 treatments. According to the CDC, the Pfizer vaccine is the only one approved for Americans under 18, with children as young as 5 being eligible. Moderna has released data for its vaccine in kids 6-11 years old. Though not a vaccine, the recently-approved Pfizer pill is also available to kids 12 and up.

Despite having a vaccine available, chid vaccination numbers are struggling to catch up with the rest of the age groups. Even in New York City, which has some of the highest vaccination rates in the country, only around 40% of 5-to-17-year-olds are fully vaccinated compared to more than 80% of adults. Across the country, fewer than 15% of U.S. children aged 5-11 have been fully vaccinated.

“What we are seeing is that children under five remain unvaccinated so there’s still a relatively large population of children who are naive, so they have no preexisting immunity to this virus,” infectious disease expert Dr. Jennifer Nayak said.