How long does a flu shot last?

You have decided to vaccinate your body against the tiny invaders known as flu. So, how long does it last? "The shot lasts long enough to protect against flu for an influenza season," said Dr. Honore Lansen, MD, of One Medical.

In other words, the vaccine you received last year will not protect you from this year's flu. And while this year's shot should protect you until the end of the flu season in the spring, you'll need it next fall. This is because the vaccine of each year is different. There are a number of influenza strains and "the vaccine is trying to predict the most prevalent strains in a given year, but it's not a perfect science," said Dr. Stephanie Long, MD, also from One Medical. "The influenza vaccine is specifically designed for the next season, that's why you should get vaccinated every year."

Experts recommend getting vaccinated before flu starts in October – or as soon as possible, if you miss this window. The duration of your protection may depend on your immune system, according to Dr. Jena Sussex-Pizula, MD, University of Southern California, Internal Medicine. "People who have a strong immune response can be protected for years, while elderly patients or those with complex medical problems can only be protected for several months," she told POPSUGAR.

Be that as it may, the message is the same: "The influenza virus itself is changing so quickly that an influenza vaccine is needed every year to track new strains of circulating influenza," said Dr. Long. You heard it – go get it!