COVID and flu hospitalizations up in Colorado, but “tripledemic” looks less likely

The odds of a “tripledemic” of respiratory viruses appear to be going down as a disease hospitalizing children recedes, but Colorado could still face a difficult winter thanks to the continued spread of flu and COVID-19.

Hospitalizations for respiratory syncytial virus, or RSV, in Colorado dropped for a second week, though the rate of hospitalizations compared to population is still more than twice as high as it was at last year’s peak. More people were hospitalized for flu and COVID-19 this week, however.

If RSV has peaked, the burden of severe illness may shift. Infants and toddlers are the most vulnerable to RSV, though older people can also develop serious symptoms. Flu hits the youngest children and the oldest adults hardest, while the odds of severe COVID-19 generally rise with age.

“It may be that the (pediatric) hospitals get a break and the adult hospitals are in for some strain,” said Beth Carlton, an associate professor of environmental and occupational health at the Colorado School of Public Health.

It’s not absolutely certain that RSV has peaked, though the declining hospitalization rate offers some reason to be optimistic, Carlton said. No one knows yet if flu and COVID-19 will peak at the same time, or if hospitals will be able to deal with one and then the other, she said.

The three viruses, combined with all of the typical illnesses and injuries that people sustain, have left Colorado hospitals fuller than they had been in months. About 91% of intensive-care beds in the state were full over the last week, which was the highest percentage since January. An average of 94% of general beds were in use, tying a high set in December 2021.

RSV created unprecedented demand for pediatric hospital beds, forcing hospitals that don’t normally treat kids to get creative. Children’s Hospital Colorado is seeing a slight decrease in hospitalizations for RSV, but now more children are coming in with serious cases of flu, spokeswoman Sarah Davis said.

“Children’s Hospital Colorado is still seeing historic increased volumes due to respiratory illness,” she said in an email. “While we saw a dip on Thanksgiving Day, we saw a rebound in volumes over the weekend and through this week.”

While there’s no vaccine for RSV, both COVID-19 boosters and flu shots can prevent the vast majority of hospitalizations and deaths from those viruses, Carlton said. People also can consider wearing masks in public, particularly if they’re at higher risk of severe illness, she said.

Since Oct. 1, the Denver area has seen 1,427 RSV hospitalizations, the vast majority of them in children. (The Colorado Department of Public Health and Environment doesn’t collect statewide data on RSV.)

Flu hospitalizations continued to rise, though somewhat more gradually than in the previous two weeks. Since Oct. 2, 517 people in Colorado have been hospitalized with the flu. The hospitalization rate is at levels typically not seen until the end of the year, and, as of Nov. 19, Colorado had “very high” flu activity, according to the Centers for Disease Control and Prevention.

COVID-19 hospitalizations also rose, from 387 on Nov. 22 to 440 on Tuesday. That likely doesn’t reflect any new infections that occurred over the Thanksgiving weekend, so it’s too early to tell if the holiday will lead to more hospitalizations, Carlton said.

For now, there’s no sign that flu and COVID-19 will be in retreat any time soon. About 19% of flu tests came back positive in the most recent week with data, and 11% of all emergency room visits in the Denver area were for flu-like illness, according to the state health department.

As of Wednesday, virus concentrations in wastewater were increasing in 44 utilities, stable in seven and decreasing in two, indicating that COVID-19 spread is increasing in much of the state.

The state health department recorded 7,339 new COVID-19 cases, a decrease of about 800, reflecting that few people got tested over a holiday weekend. About 12.8% of tests came back positive over the last week, which was slightly higher than a week earlier. It may be a good sign that the positivity rate isn’t rising as fast as it was, but the holiday testing slowdown makes it difficult to interpret that, Carlton said.

The CDC listed 17 Colorado counties as high-risk, based on their COVID-19 cases and hospitalizations: Alamosa, Eagle, Fremont, Garfield, Kiowa, Logan, Mesa, Moffat, Montezuma, Otero, Phillips, Pitkin, Prowers, Pueblo, Rio Blanco, Routt and Sedgwick. All but 10 counties had “high” or “substantial” transmission, based on their cases and the percentage of tests coming back positive.

Nationwide, the trend is similar to Colorado’s for two of the three viruses: RSV hospitalizations have started to drop, while flu hospitalizations are rising unusually early this year, according to the CDC. As of Nov. 19, the flu hospitalization rate was about eight times higher than what’s been typical for this point in the season over the last decade.