By
Chris Boyette and Jamie Gumbrecht, CNN

A surge in respiratory illnesses among children is beginning to put a strain on hospitals.

In particular, hospitals are seeing a rise in cases of respiratory syncytial virus, or RSV, a common cold virus that can be associated with severe disease in young children and older adults. Cases are rising in multiple U.S. regions, with some already nearing seasonal peak levels, according to the latest real-time surveillance data from the U.S. Centers for Disease Control and Prevention.

Surveillance data collected by the CDC clearly shows a rise in RSV cases nationwide in recent weeks, with cases detected by PCR tests more than tripling over the past two months and nearing last year's peaks. The CDC's surveillance program captures data from 75 counties representing about 9% of the total U.S. population.

"RSV admissions have skyrocketed at Connecticut Children's. October has been like never before for this virus," Monica M. Buchanan, senior director of strategic and enterprise communications for Connecticut Children's Hospital, told CNN.

Dr. Juan Salazar, executive vice president and physician-in-chief at Connecticut Children's, told CNN's Kate Bolduan that beds are filled to capacity and children are coming to the hospital at an "unprecedented" level: More than 100 with respiratory syncytial virus over the last 10 days, including many who require intensive care and oxygen therapy.

"I've been doing this for a long time, I've been at Connecticut Children's for 25 years, and I have never seen this level of surge — specifically of RSV — coming into our hospital," he said.

Salazar said the hospital hasn't yet expanded to a field tent, "but we have to be prepared in case the numbers continue to increase. So if RSV increases further and it hits us with influenza at the tail end of this ... we will need additional capacity for our hospital."

The rise in cases is also coming earlier in the year than doctors would usually expect.

"We used to have kind of a seasonality to different viruses," Dr. Thomas Murray, a pediatric infectious disease specialist and associate professor at Yale University School of Medicine, told CNN affiliate WFSB. "Like the one right now, respiratory syncytial virus or RSV would come in December, it would go away followed by influenza, it would go away and another one. What seemed to happen with COVID is that now they're all circulating at the same time."

In most of the United States, RSV typically circulates during fall, winter and spring, but the timing and severity of RSV season in a given community can vary from year to year.

In 2021, RSV peaked during the summer, so this year's fall and winter surge marks a return to circulation patterns seen in pre-pandemic years, according to a statement from CDC spokesperson Kristen Nordlund.

This shift comes as other respiratory viruses — the coronavirus that causes COVID-19, rhinoviruses, enteroviruses and flu — drive more concern, too.

Salazar said the United States is coming out of the COVID era, when children had relatively little exposure to viruses — and it's hitting them now.

"I think for the next four to eight weeks, we just have to be careful," Salazar said, adding that getting vaccinated against influenza now could help curb months of surging flu cases later.

"Get your kids vaccinated for influenza," he said. "This is the time you need to do it."

The CDC recommends that everyone age 6 months and older get a flu vaccine.

An early increase in seasonal flu activity has been reported in most of the United States, with the nation's Southeast and south-central areas reporting the highest levels of flu, according to the CDC.

"Here we are in the middle of October — not the middle of November — we're already seeing scattered influenza cases, even hospitalized influenza cases, around the country," Dr. William Schaffner, a professor in the Division of Infectious Diseases at Vanderbilt University Medical Center and medical director of the National Foundation for Infectious Diseases, told CNN.