Technically, you can get the flu any time of year, 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:
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, said infectious disease expert Dr. Amesh A. Adalja, 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. Cooler weather drives more people indoors, explained Dr. Richard Watkins, 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 said.
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, according to the CDC.
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 explained. 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 generally includes the following:
- fever or feeling feverish/having chills
- sore throat
- runny or stuffy nose
- muscle or body aches
- vomiting and diarrhea (more common in children than adults)
Has COVID-19 affected flu season?
It definitely has. “COVID has basically made flu season non-existent” in 2020 in the northern hemisphere, Adalja said. 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. Worth noting: An estimated 38 million people had the flu during the 2019-2020 flu season.
Why? “Prevention measures like mask-wearing and social distancing people are doing for COVID are also beneficial for avoiding the flu,” Watkins said.
So, what does that mean for the 2021-2022 flu season? It’s hard to say. “The southern hemisphere had a light to non-existent flu season, so that tells you that there’s less flu circulating around the planet,” Adalja said. Still, he says, it’s hard to know for sure what that means for the northern hemisphere. “I don’t think it will be an average flu season — I think it will be milder than usual.”
Regardless, experts stress the importance of getting your flu vaccine. “That’s the best way to ensure this is a mild season,” Adalja said. “It’s also an easy way to protect yourself against the flu.”