When Should You Get the Flu Shot?

Influenza is a respiratory illness that is caused by a virus. Not to mention—it's super contagious. About 8% of the US population develops the flu every year, according to the Centers for Disease Control and Prevention (CDC). Thankfully, we have an effective vaccine that protects against the flu.

The CDC recommends that everyone age 6 months and older get the flu shot every year. This recommendation is offered with the rare exception of people who have severe, life-threatening allergies to the flu vaccine or any ingredient in the vaccine.

When Is Flu Season?

In the US, flu season occurs in the fall and winter. Although influenza viruses spread throughout the year, the CDC says flu activity typically peaks between December and February but can persist until May.

When Should You Get the Flu Shot?

According to the CDC, you should wait until at least September or October to get your annual flu shot. "We want to have as many people get flu shots as possible, however, it's important to make sure that you get the flu shot when it's going to be most effective," said Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security. Dr. Adalja also recommended getting the flu shot in October, which may be "more optimal for protection."

July and August may be too early for most adults since the protection can wear off by the time flu season peaks, according to the CDC. However, children do not have to wait and can be vaccinated as soon as the vaccine is available.

Though, it should be noted that if you miss that fall deadline, you can—and should—still get the flu vaccination later in the season.

Why Should You Wait?

That specific flu shot time frame allows the body to trigger enough protection against the virus and ensure that protection can last throughout the most active parts of flu season before it wears off.

"It takes around two weeks after vaccination for enough antibodies to form and to achieve full immunity," said epidemiologist Supriya Narasimhan, MD, chief of the infectious disease department at Santa Clara Valley Medical Center.

The flu shot is most effective in the first three months after vaccination, but people still have protection for at least six months after the shot.

Why Is It Important To Get the Flu Shot?

Timeliness aside, it's especially important to get a flu shot so hospitals aren't overrun with people with influenza. "Even during non-COVID-19 years, during a bad flu season, hospitals run at capacity, and our ERs and ICUs are full," Dr. Narasimhan said.

The similarities between the flu and COVID-19 can bring more people to the hospital. "As flu and COVID-19 compete for the same hospital resources, personal protective equipment, and diagnostic reagents, it is important to try and minimize the impact of the flu," Dr. Adalja said. "Decreasing the burden of influenza is one way to make sure we have enough room for COVID-19 cases."

Besides decreasing the burden on healthcare workers, getting the flu vaccine will protect you and others from getting sick. And if you do happen to get sick, it will significantly reduce the severity of the illness. According to the CDC, it is estimated that flu vaccination prevented 7.52 million illnesses between 2019-2020 while lessening the hospital burden by 108,000 hospitalizations.

Summary

The flu shot is essential every year to protect you against contagious influenza. But when you hear that your local pharmacy is offering flu shots in the summer, you may want to wait it out a bit more—at least until September—to make sure you benefit from all the protection a flu vaccine can offer.