COVID, RSV and the flu: A case of viral interference?
Ars Technica » Scientific Method 2023-01-15
Enlarge (credit: Aurich Lawson / Getty)
Three years into the pandemic, COVID-19 is still going strong, causing wave after wave as case numbers soar, subside, then ascend again. But this past autumn saw something new—or rather, something old: the return of the flu. Plus, respiratory syncytial virus (RSV)—a virus that makes few headlines in normal years—ignited in its own surge, creating a “tripledemic.”
The surges in these old foes were particularly striking because flu and RSV all but disappeared during the first two winters of the pandemic. Even more surprising, one particular version of the flu may have gone extinct during the early COVID pandemic. The World Health Organization’s surveillance program has not definitively detected the B/Yamagata flu strain since March 2020. “I don’t think anyone is going to stick their neck out and say it’s gone just yet,” says Richard Webby, a virologist at St. Jude Children’s Research Hospital in Memphis. But, he adds, “we hope it got squeezed out.” Such an extinction would be a super rare event, Webby says.
But then, the past few years have been highly unusual times for human-virus relations, and lockdowns and masks went a long way toward preventing flu and RSV from infiltrating human nostrils. Still, Webby thinks another factor may have kept them at bay while COVID raged. It’s called viral interference, and it simply means that the presence of one virus can block another.