Twin COVID-19, Flu Outbreaks Possible This Winter: Studies

PITTSBURGH, PA — Remember the ordinary flu? Influenza took a backseat to the coronavirus last year, but University of Pittsburgh's Graduate School of Public Health scientists predict it is poised to make a significant comeback.

Two new Pitt studies indicate the 2021-22 flu season likely will be more severe than average and affect young children particularly hard. That's because immunity levels are down from the near-total lack of a flu season during last winter's coronavirus surge.

Scientists are cautioning that means the possibility exists for a medical crisis not experienced last year: a 'twindemic' of coinciding flu and COVID-19 epidemics.

"Our models show that we should be more concerned this year about the possibility of a surge in COVID-19 hitting at the same time as a massive flu outbreak in areas of the country with low vaccination rates against both diseases, ” said Dr. Mark Roberts, director of the Public Health Dynamics Laboratory at Pitt Public Health and senior author of the two studies.

How to prevent a massive flu outbreak? Both studies suggest that increased flu-related hospitalizations and deaths can be prevented if vaccination rates rise between 20 percent and 50 percent over recent flu season levels.

That's necessary because as COVID-19 containment measures decrease worldwide, other respiratory ailments are making a significant resurgence.

“In a worst-case situation with a highly transmissible flu strain dominating and low influenza vaccination uptake, our predictive models indicate the potential for up to nearly half a million more flu hospitalizations this winter, compared to a normal flu season," Roberts said. "Vaccinating as many people against flu as possible will be key to avoiding this scenario.”

The two independent analyses used different mathematical modeling platforms but both produced consistent complimentary results.

One study found that the 2021-22 flu season could have around 20 percent more flu cases than normal, though potentially there could be double the typical caseload, which is between 9 million and 45 million illnesses in the U.S.

The other predicted the coming influenza season will likely bring about 600,000 hospitalizations, at least 100,000 more than would happen in a typical season. In a worst-case scenario where vaccine rates are low, there could be more than 400,000 additional hospitalizations.

Getting 75 percent of Americans vaccinated against flu, rather than the typical 50 percent, would be needed to avoid the additional hospitalizations, according to the study.

Be the first to know what's happening in your community and region. With a free Patch subscription, you'll always be up to date on local and state news: https://patch.com/subscribe.