Weeks before the temperature outside approaches light jacket weather, drug stores are already bombarding their customers with reminders of flu season. The flu shot campaign starts with the arrival of the first vaccine shipment in August and lasts through to April or May. The convenience of getting the shot out of the way weeks or even months before the virus becomes a real threat may seem appealing to some, but according to NPR, getting vaccinated too early could cost you.

We know that getting inoculated against the flu reduces our risk of catching it by about 60 percent, but just how long that immunity lasts remains a bit of a mystery. Some research shows that vaccines grow less effective over the course of one flu season. With the flu sometimes sticking around until spring, it’s then possible that those who get their shots early in the year will be left vulnerable at the end of a late season.

This should be of particular concern to people over 65. The older someone is, the more trouble their immune system has responding to the vaccine, and the effects may not last as long as they would in younger recipients. 

So when is the best time to get the shot? Flu season typically begins in the fall, with the virus reaching peak activity around January and February. With that in mind, immunologist Laura Haynes tells NPR she recommends getting the shot sometime between Halloween and Thanksgiving. But if that doesn’t happen to fit your schedule, health experts say it’s better to get the shot early than to skip it altogether.

[h/t NPR]

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