Is it flu, RSV, or COVID? Experts fear the ‘tripledemic’


Just when we thought this holiday season, finally, would be the back-to-normal one, some infectious disease experts are warning that a so-called “tripledemic” – influenza, COVID-19, and RSV – may be in the forecast.

The warning isn’t without basis.

The flu season has gotten an early start. As of Oct. 21, early increases in seasonal flu activity have been reported in most of the country, the Centers for Disease Control and Prevention said, with the southeast and south-central areas having the highest activity levels.

Children’s hospitals and EDs are seeing a surge in children with RSV.

COVID-19 cases are trending down, according to the CDC, but epidemiologists – scientists who study disease outbreaks – always have their eyes on emerging variants.

Predicting exactly when cases will peak is difficult, said Justin Lessler, PhD, a professor of epidemiology at the University of North Carolina at Chapel Hill. Dr. Lessler is on the coordinating team for the COVID-19 Scenario Modeling Hub, which aims to predict the course COVID-19, and the Flu Scenario Modeling Hub, which does the same for influenza.

For COVID-19, some models are predicting some spikes before Christmas, he said, and others see a new wave in 2023. For the flu, the model is predicting an earlier-than-usual start, as the CDC has reported.

While flu activity is relatively low, the CDC said, the season is off to an early start. For the week ending Oct. 21, 1,674 patients were hospitalized for flu, higher than in the summer months but fewer than the 2,675 hospitalizations for the week of May 15, 2022.

As of Oct. 20, COVID-19 cases have declined 12% over the last 2 weeks, nationwide. But hospitalizations are up 10% in much of the Northeast, The New York Times reports, and the improvement in cases and deaths has been slowing down.

As of Oct. 15, 15% of RSV tests reported nationwide were positive, compared with about 11% at that time in 2021, the CDC said. The surveillance collects information from 75 counties in 12 states.

Experts point out that the viruses – all three are respiratory viruses – are simply playing catchup.

“They spread the same way and along with lots of other viruses, and you tend to see an increase in them during the cold months,” said Timothy Brewer, MD, professor of medicine and epidemiology at UCLA.

The increase in all three viruses “is almost predictable at this point in the pandemic,” said Dean Blumberg, MD, a professor and chief of pediatric infectious diseases at the University of California Davis Health. “All the respiratory viruses are out of whack.”

Last year, RSV cases were up, too, and began to appear very early, he said, in the summer instead of in the cooler months. Flu also appeared early in 2021, as it has in 2022.

That contrasts with the flu season of 2020-2021, when COVID precautions were nearly universal, and cases were down. At UC Davis, “we didn’t have one pediatric admission due to influenza in the 2020-2021 [flu] season,” Dr. Blumberg said.

The number of pediatric flu deaths usually range from 37 to 199 per year, according to CDC records. But in the 2020-2021 season, the CDC recorded one pediatric flu death in the U.S.

Both children and adults have had less contact with others the past two seasons, Dr. Blumberg said, “and they don’t get the immunity they got with those infections [previously]. That’s why we are seeing out-of-season, early season [viruses].”

Eventually, he said, the cases of flu and RSV will return to previous levels. “It could be as soon as next year,” Dr. Blumberg said. And COVID-19, hopefully, will become like influenza, he said.

“RSV has always come around in the fall and winter,” said Elizabeth Murray, DO, a pediatric emergency medicine doctor at the University of Rochester (N.Y.) Medical Center and a spokesperson for the American Academy of Pediatrics. In 2022, children are back in school and for the most part not masking. “It’s a perfect storm for all the germs to spread now. They’ve just been waiting for their opportunity to come back.”


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