By the summer of 2020, the U.S. medical community was braced for what some were calling a “twindemic” fall and winter, with COVID-19 cases added to a typical influenza season. But that dire prediction hasn’t come to pass.

By mid-December, there was less flu activity in nursing homes and the general public than expected, epidemiologists at the Centers for Disease Control and Prevention said at the time. And although COVID-19 numbers have spiked in recent months, overall seasonal flu activity has remained at lower-than-usual levels, current federal data show. 

In fact, of the approximately 800,000 laboratory samples that have been tested for flu since early fall, only about 0.2% have been positive. The Mayo Clinic’s virology lab, in another example, ran 10 times the number of flu tests than it did last season and has had zero positive results, according to The Atlantic. “While the coronavirus has surged, the flu and other respiratory viruses have flickered out,” Katherine J. Wu reported.

The same trend is happening globally, and scientists aren’t exactly sure why, Wu wrote. One obvious conclusion is that COVID-19 mitigation measures — especially travel bans — have managed to wipe out flu transmission. Flu happens to be less transmissible than COVID-19, and so these measures may have been more successful for one disease than the other.  

In addition, federal health authorities and pharmacies planned ramped-up vaccination campaigns for the 2020-2021 flu season, which may have worked. More adults appear to have received flu vaccinations in pharmacies during the current flu season than in the 2018-2019 flu season, according to a December report by Healthline. 

The flu will certainly make a comeback, experts say. But this season’s low infection rate may reaffirm that public health infection control measures actually work, flu expert Seema Lakdawala, Ph.D., of the University of Pittsburgh, told The Atlantic.

“We have a glimpse of what could be very effective,” she said. “I’m really hopeful that when people are sick, either they stay home and/or they put on a mask when they have to go out.”