Between COVID-19, RSV, and the flu, there has been an onslaught of respiratory virus news over the past few years. While a recent jump in COVID-19 cases and new strains of the virus have gotten a lot of airplay, flu season is coming up fast.
Technically, you can get the flu any time, but the virus does tend to infect people more during certain times of the year, beginning in the fall. When is flu season exactly, though? Here’s what you need to know.
Meet the experts: Amesh A. Adalja, M.D., an infectious disease expert and a senior scholar at the Johns Hopkins Center for Health Security; Richard Watkins, M.D., an infectious disease physician and professor of internal medicine at the Northeast Ohio Medical University; and Thomas Russo, M.D., a professor and chief of infectious diseases at the University at Buffalo in New York.
When is flu season in the U.S.?
Flu season varies across the world: The southern hemisphere, which has its summer when we have our winter and vice-versa, goes through flu season during opposite times as the northern hemisphere, says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security.
The exact timing of flu season can vary but, in the U.S., flu activity usually starts to pick up in October, according to the Centers for Disease Control and Prevention (CDC). Cooler weather drives more people indoors, explains Richard Watkins, M.D., an infectious disease physician and professor of internal medicine at the Northeast Ohio Medical University. “More people inside means they’re more likely to transmit viruses,” he says.
From there, flu season typically peaks in December and February, before petering out in the springtime. Some seasons, heightened flu activity can last as late as May, the CDC says.
Does flu season change from year to year?
It can. There’s not one set day on the calendar when the flu starts up in the U.S. and then another when it disappears, says Thomas Russo, M.D., a professor and chief of infectious diseases at the University at Buffalo in New York. “Flu season can vary a little bit,” he says. “It tends to show up after Halloween in terms of cases really increasing, but it depends.”
Variations in timing can be due to which strains are circulating, when they showed up from the southern hemisphere, and how much lingering immunity people have from the previous flu season, Dr. Russo says. “As a general rule, though, flu activity is the highest in December and January,” he adds. “That makes sense with people getting together over the holidays.”
Why the flu is a concern
The flu is a contagious respiratory illness that’s caused by influenza viruses, according to the CDC. The flu can cause illness that ranges from mild to severe, and it can be deadly.
The flu mainly spreads through tiny droplets that are created when someone with the flu coughs, sneezes, or talks, the CDC explains. Those droplets can then land in the mouths or noses of other people and infect them. It’s less common, but a person might get the flu by touching an infected surface and then touching their mouth, nose, or eyes.
Flu symptoms usually come on suddenly and they can vary, but the CDC says they generally include the following:
“Flu is a potentially lethal virus that kills tens of thousands of people each year,” Dr. Russo explains. “No one is risk-free when it comes to getting the flu, and even young, healthy people feel pretty miserable when they have it. It’s a serious virus that deserves our respect.”
Has COVID-19 affected flu season?
COVID-19 can impact flu season, Dr. Russo says. During the peak of the pandemic in 2020, COVID-19 “basically made flu season non-existent,” Dr. Adalja says. Case in point: There were just a little more than 2,000 flu cases reported to public health officials between late September 2020 and late April 2021, according to CDC data. But an estimated 36 million people had the flu during the 2019-2020 flu season.
Now, flu cases have rebounded, with an estimated 26 to 50 million flu cases, 290,000 to 670,000 hospitalizations, and 17,000 to 98,000 deaths from flu last year, per the CDC. (The data is still preliminary at this point, which is why the CDC gives a range.)
New COVID-19 strains have also been circulating and challenging immunity from previous infections and the vaccine—that caused a late-summer wave of infections that is still ongoing, Dr. Russo says.
“COVID has changed flu season a little bit,” Dr. Russo says. “These viruses seem to be in competition.” Meaning, when cases of COVID-19 are high, cases of the flu tend to be lower, and vice-versa. “If you have a COVID wave, you tend not to have a flu wave at the same time,” he says.
For this season, Dr. Russo says it’s unclear which wave will come first. “We’re still learning the rules of timing with these,” he says. “There are multiple viruses playing the same sandbox and it’s hard to know how this season will play out.”
Regardless, experts stress the importance of getting your flu vaccine. “That’s the best way to ensure this is a mild season,” Dr. Adalja says. “It’s also an easy way to protect yourself against the flu.”
Another thing you can do? Wash your hands. “Hand hygiene is vital,” adds.
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Gary Rose is a lifestyle connoisseur who celebrates the art of living well. She explores topics ranging from travel and fashion to home decor and culinary delights. Gary’s passion for aesthetics extends to her hobbies, which include photography and interior design.