Close up of a healthcare worker cleaning a person's skin in preparation for a vaccination.

Flu season has started in earnest in the U.S., and during the last week of November, 3.5 percent of people who visited doctors reported symptoms of the virus, according to the Centers for Disease Control and Prevention. That’s the highest number for this point in the year since 2009. 

This time last year, the percentage of doctor’s visits for flu-like illness was 2.2, and in 2017, it was 2.3 percent. 

“We’re seeing influenza activity a little bit earlier than we do in most seasons,” says Scott Epperson, D.V.M., an epidemiologist with the CDC’s domestic flu surveillance team.

And vaccination rates may be low. Only 52 percent of U.S. adults said they planned to get the flu shot, in a National Foundation for Infectious Diseases survey conducted earlier this fall.

more on the flu

But it’s not clear exactly what all this signals for the rest of flu season. “Flu is a very mutable virus. Lots of changes can happen from the beginning of the season to the end of the season,” says Amesh Adalja, M.D., senior scholar at the Johns Hopkins University Center for Health Security.

One slight anomaly for this season, according to Epperson, is that the predominant strain of flu right now is influenza type B. Typically influenza type A strains are most common early in the flu season, and flu B tends to circulate more later on.

But flu—including the strains that circulate and the severity of the season—is notoriously unpredictable, so you want to make sure you’re protected by a vaccine (which works against both type A and type B strains). If you’ve been putting off your shot, now is the time to get it. It can take about two weeks after being vaccinated to develop antibodies to fight off the virus. Here, three reasons not to delay.

The Flu Shot Is Effective

In the National Foundation for Infectious Diseases survey, half of those who indicated they didn’t plan on getting a shot said they didn’t believe the vaccine made any difference. 

It’s true that the flu vaccine isn’t perfect, and some years it’s more protective than others. The CDC estimates that last season’s vaccine was 29 percent effective overall. Still, that means that about a third of people who received the shot who were exposed to flu didn’t get sick. 

Plus, even if you get vaccinated and still contract the flu, you’re less likely to get seriously ill or be hospitalized from the illness.

Your Flu Shot Protects Others

If you’re a healthy adult, you may not be all that worried about getting the flu, because beyond making you feel lousy for a week, chances are it won't cause you serious harm.  

But children younger than 5, the elderly, pregnant women, and those with chronic health problems are more likely to suffer complications from the flu. The flu vaccine also tends to be less effective in some of these people.

That’s one reason the CDC recommends that healthy adults get the flu vaccine: If enough people are protected from the flu with a vaccine, those most at risk for complications can be protected as well—a phenomenon known as herd immunity. That’s also why it’s especially important to get your shot if you live or work with young children, older adults, or people with certain medical conditions.

The CDC has estimated that between 2005 and 2014, the flu vaccine averted roughly 40,000 flu-related deaths.

The Flu Shot Is Affordable and Safe

Currently, insurance plans are required to cover your flu shot with no co-pay and no co-insurance. If you’re uninsured, your local health department may provide resources on where to get a flu shot at little or no cost. And if your doctor’s office or employer is not offering flu shots, you can find options near you at vaccinefinder.org.

The vaccine is safe for almost everyone. People with life-threatening allergies or a history of Guillain-Barré syndrome should talk with their doctor before they get a flu shot. Severe allergic reactions are extremely rare.

Some people think you can actually get the flu by having a flu shot. But this is a myth: The flu vaccine is made with inactivated or dead (or, in the case of the nasal spray vaccine, weakened) viruses, so it can’t cause the flu. It can, however, cause minor side effects such as soreness at the site of the injection, headache, body aches, and fever.