Typically, the winter months bring the peak of flu season. As cases of COVID-19 have soared in the U.S. over the past few weeks, however, cases of the flu have remained extremely low.
Flu season typically peaks between December and February each year. The Centers for Disease Control and Prevention estimates that the flu causes up to 45 million illnesses, up to 810,000 hospitalizations and up to 61,000 deaths each year. But this flu season, there have been just 925 cases of the flu around the U.S so far.
"Though caused by a different virus from the one that causes COVID-19, the flu is also a respiratory viral disease, so everything we are doing to slow transmission of COVID-19, such as wearing face masks, frequent handwashing and physical distancing, should also reduce transmission of flu," says Eili Klein, Ph.D., associate professor of emergency medicine at the Johns Hopkins University School of Medicine.
More people also received the flu vaccine this season compared with last season, many schools and businesses are holding virtual classes or meetings instead of in-person, and fewer people have been traveling—all of which could be keeping flu cases down.
"We commonly see flu spread in communities, schools, businesses and through travel each year, so these changes are likely keeping the flu away," says Lisa Maragakis, M.D., M.P.H., senior director of infection prevention for the Johns Hopkins Health System and associate professor of medicine at the Johns Hopkins University School of Medicine.
Klein believes that even if this flu season turns out to be less severe than usual, it could affect the severity of the next flu season. "Because of the current restrictions and precautions everyone is taking this season, far fewer people will be infected or exposed to the flu virus, and therefore won't become immune to certain strains of the virus," he says. "So the number of people who may have more severe infections next year is likely to be greater because immunity will be lower."
Flu season typically runs through May, so there's still a chance that flu cases will pick up in the next few months. Also, one strain of flu—influenza B—tends to circulate later in the season.
Johns Hopkins Medicine experts recommend continuing prevention methods to protect against the flu and COVID-19 as well as getting the flu vaccine. "The flu vaccine takes about two weeks for antibodies to develop and begin protecting you from the illness, so getting the flu vaccine any time through mid-April will still be helpful in preventing the flu," Maragakis says. She advises that anyone who hasn't already gotten their flu vaccination should do so as soon as possible, but she notes that 14 days must elapse between getting the COVID-19 vaccination and any other vaccinations, including the flu vaccine.
Maragakis and Klein are available for interviews on this year's flu season and the potential effects on next year's flu season.
Provided by Johns Hopkins University