When Should You Get A Flu Shot?

While many of us are still mourning the end of summer or prepping to go back to school, the Pumpkin Spice Lattes are brewing and fall is imminent, which means that cold and flu season is waiting around the corner, too. You might be wondering whether you need to get your flu shot now, or if it makes more sense to wait until it's less than 90 degrees outside. And just like some people think it's "too soon" for PSLs, it can be too early to get a flu shot.

Usually, outbreaks of the flu happen in the winter months, says Ebbing Lautenbach, MD, MPH, MSCE, professor of epidemiology and chief of the division of infectious diseases at the Perelman School of Medicine, University of Pennsylvania. The flu usually picks up in October, then spikes in December and February, and can last through May, according to the Centers for Disease Control (CDC). But the start of flu "season" and the duration can vary from year to year, which is why it can be difficult to plan your flu shot.

In general, the best time to get a flu shot is before the onset of flu activity in your community, Dr. Lautenbach says. So, you should probably get your shot before the end of October if you are in the U.S., he says. When you get a flu shot, your body creates antibodies that protect you against three or four specific viruses that are in the vaccine, according to the CDC. But it takes about two weeks after you get the flu vaccine for you to develop antibodies against the flu (aka for it to "work"), he says. "That's why it's important to get vaccinated before there is significant flu activity in the region," he says.

Now, if you're really hype about not getting sick this year, that's great, but it's still worth it to wait until there are cases of flu in your region to get the shot. "The potential downside of getting it too early, is that the effectiveness of the vaccine will wane over time, which could mean that the protection of a vaccine given early in the season will be less if the peak of the flu season is later," Dr. Lautenbach says. (August is typically too soon, for what it's worth.) On the flip side, as long as there are cases of the flu in your area, it's never too late to get the vaccine, he says. "If you can only get the vaccine at earlier or later times, it's still much better to get the vaccine versus not getting it at all," he says.

At the end of the day, the flu shot is one easy step that you should take to prevent the flu this year, but it's not perfect. The flu shot takes months for scientists to develop and manufacture, because it requires looking at the strains that were prominent in prior years, and predicting what will be around this year, Dr. Lautenbach says. So, the vaccine strains have to match whatever is circulating in order for it to be effective. "That said, even if the match of the vaccine to the circulating strains isn’t great, the vaccine still reduces illness and death from flu," he says. So mark your calendar, and plan to get your shot before October, when it's seasonally appropriate for a PSL.