Whew.

The “tri-demic” local health professionals had feared and warned the public about for months — the confluence of influenza, RSV and COVID-19 overwhelming health systems — appears to have been averted.

The triple respiratory illness threat was real because masking and social distancing practices during the pandemic meant fewer children were getting infections, thus immunity levels were lowered, local health professionals told the Denver Gazette. Children were more susceptible to contracting RSV when the mitigation efforts were dropped.

“The tri-demic that you’re talking about, all three viruses are here,” said Dr. Sam Dominguez, a pediatric infectious disease expert at Children’s Hospital Colorado. “It really strained our health care system.”

For example, the Children’s Hospital in November redeployed its patient care tents outside the emergency department of its Anschutz Campus location because of the record number of patients with respiratory illnesses.

While the three viruses are still circulating in the community, it's not at the level health professionals saw in the fall.

“Boy, if the trend we had seen early on had continued, we would have been in trouble,” said Dr. Michael Roshon, an infectious disease specialist with Centura Health.

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Across the Denver metro area in November, Centura hospitals had roughly 300 pediatric and adult patients hospitalized with RSV, a common respiratory disease that can be serious for the very young and old. About 90% of those hospitalized with RSV were children.

This week, that number was down to around 100, Roshon said. Pediatric patients with RSV now account for about 67% of hospitalizations.

Typically, RSV and influenza peak in February.

State health data shows the RSV infection rate this season was the highest since at least 2018 and nearly twice as high as the next worst spike in the 2021-2022 season.

“It was pretty dramatic,” Roshon said of the drop in hospitalizations. “Something must have happened to change the trajectory.”

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In a sign that the worst of the winter diseases may be over, hospitals deactivated what’s called the "transfer center" for pediatric patients with respiratory illnesses before the holidays.

Two years ago, infection control experts had warned of a “twin-demic” with the convergence of influenza and COVID-19, but the threat didn’t materialize then, largely because of masking and social distancing.

Those measures, first broadly implemented in the pandemic, may have helped hospitals skirt the triple respiratory threat.

“The RSV surge is likely behind us,” Dominguez said.

That that doesn’t mean the public should let down their guard.

The epidemiological team at Denver Health warns of a possible uptick in transmissions and hospitalizations following the gatherings from the holidays.