This year's flu season has kicked off to a strong start, with more than 23,000 patients admitted to the hospital with the flu last week. Mixed with high levels of respiratory syncytial virus (RSV) and Covid-19, the "tripledemic" is stretching many hospitals to their capacity.

Where the flu season stands now

According to CDC, Alaska and New Hampshire are reporting low levels of influenza-like illnesses (ILI) while Delaware, Michigan, and Hawaii are reporting moderate levels. Every other state is reporting either high or very high levels of ILI.

For the week ending in Dec. 10, 23,503 patients were hospitalized with the flu. In addition, the percentage of ILI outpatient provider visits was 6.9%, down from 7.2% the week before but still higher than the national baseline of 2.5%.

So far this flu season, CDC estimates that there have been at least 15 million flu illnesses, 7.3 million flu medical visits, 150,000 flu hospitalizations, and 9,300 flu deaths.

There were nine pediatric deaths from the flu reported the week ending in Dec. 10—bringing the total number of pediatric flu deaths this season to 30.

'This is unprecedented'

Experts say flu cases may be close to peaking, but caution that the flu outbreak will turn into waves of illness in the early spring that could collide with Covid-19.

"The concern is, the viruses have been so weird this year, we don't know," said Sarah Ash Combs, an ED physician at Children's National Hospital. "Whereas we can typically predictively say, 'OK that was the peak, we're now on the down spike. We don't know: 'Is there going to be a second spike? A January, a February, a March spike?'"

"Typically what we see is, after the holidays, after Christmas and New Year's, illness starts to increase and it peaks in late January, early February, and then declines," said Alex Davidson, an epidemiologist for Kinsa, which forecasts infections disease outbreaks using smart thermometers.

But since there have been so many illnesses so early in the flu season, it's likely to peak closer to next week with sustained high levels of multiple respiratory illnesses for some time, Davidson said.

"Between essentially Oct. 16 and early March, we're looking at a lot of illness," he said, adding, "This is unprecedented."

The surge of flu and RSV cases has especially hit pediatric hospitals hard. According to Erica Michiels, director of pediatric emergency medicine at Corewell Health Helen DeVos Children's Hospital, their ED typically sees around 140 kids each day, but on a Tuesday in mid-December, they saw 253.

In response to the surge in patients, DeVos Children's has doubled up their rooms and is not allowing more than one parent or guardian to stay overnight. Still, according to Andrea Hadley, chief of pediatric medicine at the hospital, DeVos Children's only has capacity for the sickest children.

"We've had to say, 'We see you, we're going to support you, but we can't bring you here yet,'" she said.

Staff shortages have added to the strain. According to the Michigan Health & Hospital Association, the state has lost 1,700 staffed hospital beds since 2020. At Children's Hospital of Michigan, there's only enough staff to cover around 60% of beds, according to Rudy Valentini, the hospital's CMO.

"So we have ICU patients in our emergency department that can't get up to our ICU, because either there's no available beds, there's no available staff beds," he said.

RSV cases also appear to be more severe than they have been in years past. In a survey of 100 physicians published Dec. 14, 64% of respondents said RSV cases are more severe than in prior years.

"These kids are just so much sicker [than we typically see during RSV season,]" said Jamie West, a nurse manager at DeVos Children's. "And when you think about nurses that are already in very large patient assignments, nurses are very worried that their child's going to go downhill very quickly, that they're going to maybe miss something because they're spread so thin."

Some children are also showing up to hospitals infected with both the flu and Covid-19. According to CDC's Morbidity and Mortality Weekly Report, surveillance data has shown that 6% of flu-related hospitalizations and 16% of flu deaths involved children who had both the flu and Covid-19.

Children co-infected with both diseases were more likely to require either BIPAP or CPAP machines than those who only had the flu and were more likely to need invasive mechanical ventilation, CDC found. (Reed, Axios, 12/16; Wells, "Shots," NPR, 12/15; Carbajal, Becker's Hospital Review, 12/14; Hein, MedPage Today, 12/15)