Dr. Kwong said that people at higher risk for flu complications, including those who are pregnant, 65 or older or who have conditions like asthma, heart disease or diabetes, may want to get their flu vaccine as soon as possible. People living in parts of the United States that already have moderate or high flu activity, such as Texas, New Mexico, Delaware and Georgia, should get vaccinated as soon as possible, too. (To see what flu activity is like where you live, scroll down to the map on this webpage.)
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For optimal protection, though, some people may want to wait.
If you aren’t at high risk for complications and flu activity is low where you live, and if you are the type of person who likes to optimize your flu protection, waiting another month or two could be a wise choice, the experts I spoke with said. Dr. Nuzzo said she usually gets her flu shot in October, while Dr. Kwong said he often waits until November.
Waiting can make sense because people are more likely to encounter the flu virus in the winter rather than in the early fall — and the protection afforded by the flu vaccine wanes over time, said Emily Martin, an infectious disease epidemiologist at the University of Michigan School of Public Health.
Dr. Martin and her colleagues published a study in 2021 that found the ability of the flu shot to protect against flu-induced hospitalization dropped by 8 to 9 percent each month after vaccination across four flu seasons. A 2019 study reported that the odds of catching the flu went up by 16 percent every 28 days after vaccination. This is relevant considering that last flu season, the flu was still spreading in March, April and even June in some U.S. regions, perhaps because people were ramping up travel and loosening Covid restrictions. If you got your flu vaccine in August, or if you get it in September, you may not be protected against flu during the spring and early summer months, Dr. Kwong said.
That said, the vaccine may still partially protect you after seven or eight months, Dr. Martin said. So don’t fret if you got your vaccine already. Getting the flu vaccine early is better than not getting it at all, she added.
Wear a mask in crowded indoor spaces and wash your hands regularly.
Even if the flu isn’t yet spreading where you live, experts recommend wearing a mask in crowded indoor spaces. “Masking helps reduce the spread of a lot of respiratory viruses, not just flu,” Dr. Martin explained, and in the early fall there can be 20 or more viruses circulating because of back-to-school spread, she said. Dr. Kwong recommended wearing high-quality, well-fitting masks, such as N95s, KN95s or KF94s. If that’s not possible, surgical masks are more protective than cloth masks, but cloth is better than nothing at all, he said.