Uncertainty looms over flu season every year, but this time there are even more unknowns than usual — from precisely what strains will be circulating to how the virus will interact with Covid-19 to whether our new pandemic habits will impact its spread. “This year, in particular, we don’t know what to expect,” says Stacey Schultz-Cherry, an influenza researcher at St. Jude’s Children’s Research Hospital.
Early in the year, scientists start looking at what strains of influenza are circulating around the world, especially south of the equator, just before their full flu season starts. But this year, we are largely missing this crucial piece to the puzzle because the Southern Hemisphere has seen very little flu.
The paucity of flu cases in the Southern Hemisphere this year also means that we haven’t been able to learn much about how Covid-19 interacts with influenza.
Some case reports from early in the pandemic, when the flu was still circulating in China over the winter, showed that some people did have simultaneous infections.
“We really don’t know what a co-infection would look like,” Schultz-Cherry says. But, she says, “I wouldn’t want to have the lungs that would find that out.” She does hypothesize that it would be “a more significant infection” — especially in those at a higher risk for severe Covid-19 and for severe flu illness.