En español | If you haven’t already received your flu shot, do so soon. That’s the official recommendation from the Centers for Disease Control and Prevention (CDC), which encourages everyone to get vaccinated by the end of October.
As of Oct. 19, the agency noted that flu activity was still low across most of the country, which is typical for this time of year. Louisiana and Puerto Rico, however, reported high levels of flu-like illness.
It takes about two weeks after receiving the flu shot for your body to build up immunity to the virus, which is why getting vaccinated in the early fall, before flu activity typically increases, is recommended.
Adults age 65 and older are encouraged to opt for the high-dose or adjuvanted versions of the vaccine. If those options aren’t available at your doctor’s office or local pharmacy, get the regular shot instead, says William Schaffner, M.D., medical director of the National Foundation for Infectious Diseases.
“A vaccine deferred is often a vaccine never received,” Schaffner says. Getting your flu shot promptly, experts say, is more important than seeking out a particular formulation.
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While there is no shortage of the flu shot, manufacturing got a late start this year due to a delay in the process of finalizing this season’s vaccine formula. That delay, along with the growing popularity of the high-dose vaccine in particular, could explain any local gaps in availability.
According to the CDC, more than 140 million flu shots have been distributed so far, and shipments will continue into the fall.
If you do come down with the flu after getting vaccinated, your symptoms are likely to be less severe, with a lower risk of complications such as hospitalization.
That benefit is particularly important for older adults, who are at greater risk of severe — sometimes deadly — complications from the flu.
Editor's note: This article was originally published on Sept. 26, 2019. It has been updated with additional information about the 2019-2020 flu season.