Is it too late to get a flu shot?

You know getting your flu shot is the best way to avoid getting the flu (aka influenza), a potentially life-threatening respiratory infection that can cause fever, a dry cough, headache, muscle aches, and fatigue. 

But September, October, and even November have already passed and you still haven’t gotten your vaccine. Are you too late?

What’s the best time to get a flu shot?

The Centers for Disease Control and Prevention (CDC) recommends that people aged 6 months and older get an annual influenza vaccine. It’s particularly important for people at higher risk of complications from the flu, including young children, pregnant women, older adults, and those who have chronic health conditions, such as asthma or diabetes.

While the influenza virus can circulate year round, flu cases typically start popping up in October, peaking in December, January, February, and sometimes March, then tapering off in the spring. But because it can take two weeks for your body to build up immunity to the virus post vaccination, the CDC recommends that everyone get their flu shot by the end of October, before flu season really amps up. 

And getting your vaccine earlier than September or October isn’t always better. Research shows that the flu vaccine’s effectiveness can wane by 6%–11% per month post-vaccine. An adult who gets an early vaccination—say, in July or August—may not have enough immunity left to fend off the flu later in the season. An exception to the early rule: Children getting their very first flu shot. Because it’s a two-shot series with the second shot being given four weeks after the first, it’s recommended that these children get their first jab as soon as the vaccine becomes available, even if it’s July or August. Early vaccination can also be considered for expectant mothers in their third trimester to help protect babies in their first few months of life when they are too young to receive the vaccine.

So far this year, only 19% of Americans have received their flu vaccine, according to a SingleCare survey, while another 36% intend to do so at some point. Overall, the number of people who have gotten or plan to get a flu shot is down about 3% from last year. 

And while a third of people in our SingleCare survey think the flu shot isn’t effective in preventing a flu infection, that just isn’t the case. The CDC reports that in 2020, the flu vaccine helped prevent some 7.5 million flu illnesses, 3.7 million medical visits, 105,000 influenza hospitalizations, and 6,300 flu-associated deaths. In years when the vaccine is well matched to circulating strains, it can reduce flu illnesses by up to 60%. Even if you do get the flu despite vaccination, your chances of being hospitalized with a flu infection or dying from the virus are substantially lower than someone who isn’t vaccinated.

Is it too late to get a flu shot?

As long as the flu virus is circulating—and that can be well into the spring—experts say it’s not too late to get a flu shot. “Whatever protection you can get, even from a shot late in the season, is better than no protection,” says Julia Blank, MD, a family medicine physician at Providence Saint John’s Health Center in Santa Monica, Calif. 

Determining how long and aggressive a flu season will be isn’t an exact science. While the flu usually peaks in fall and winter, there have been times flu activity has stretched into May and beyond. In fact, between May and late September of 2019, the CDC reported 1,700 positive cases of flu.

“The rates of flu can sometimes be higher toward the end of the season,” says Charles Daley, MD, a pulmonologist and chief of mycobacterial and respiratory infections at National Jewish Health in Denver. “It’s worth getting vaccinated at any time during the flu season.”

What if I’ve already been exposed?

If you’ve already been exposed to—or even been sickened by—the flu this season, it still pays to get a flu shot. That’s because there are actually multiple flu strains, with Influenza A and B accounting for most cases of seasonal flu in this country.

So although you may have been exposed to or even gotten sick and recovered from one strain of flu, without a flu shot, your body won’t have the antibodies to protect you from other circulating strains. “Getting sick from one strain doesn’t protect you from getting sick with another one,” emphasizes Dr. Blank.

Who should not get the flu shot?

The flu vaccine is considered safe and effective for most people, but there are certain people who should not receive certain kinds of flu vaccines. 

For example, a high-dose inactivated vaccine is only approved for use in those 65 and older. Those older than 2 and younger than 50 are the only groups approved to take the nasal spray vaccine (and even then, certain groups—such as pregnant women or those who are immunocompromised—should not receive this type of vaccine). Your healthcare provider can advise about which vaccine is the safest and most effective for you.

And there’s also a small subset of people who should not receive any flu vaccine at all. According to the CDC, these people include:

• Babies younger than 6 months
• People who have a severe allergy to any ingredient in the vaccine—for example, gelatin, antibiotics, or other ingredients. 

If you have an egg allergy (certain flu vaccines contain a small amount of egg protein) or you’ve had Guillain-Barre Syndrome (a rare disorder, linked to some vaccines, in which your immune system attacks nerves), get medical advice from your doctor before receiving a flu vaccine. Depending on your particular situation, your doctor may decide that receiving the vaccine outweighs any potential risks. You might also need to get the vaccine in a healthcare setting, so you can be closely observed by medical personnel.

You also may need to wait to get a flu vaccine if you’re sick with anything other than a mild illness (think the common cold or sinus or ear infection) or you have a mild-to-moderate fever. “In part, this is because people with fevers are usually excluded from vaccine studies, so we don’t know how the vaccine may affect them and whether it will be as effective,” Dr. Daley says. “We don’t know if the antibody response will be as robust if someone’s immune system is trying to develop antibodies to fight off the current infection. The CDC recommends waiting if you have a fever greater than 101 degrees F or if you are very ill.”

What about getting the COVID-19 vaccine or a booster shot along with the flu vaccine? Experts say that’s completely fine. “A recent study from the U.K. showed that getting a flu shot with a COVID vaccine did not affect antibody response,” Dr. Daley says. “So, there is no reason to wait. However, if someone is getting their first COVID vaccine, I would recommend that they wait a couple of weeks before getting the flu shot so that if they develop a COVID vaccine reaction, it’s clear which vaccine is causing it.”

RELATED: What are the most common flu shot side effects?

Where are flu shots available?

During flu season, flu vaccines are available in a number of places:

• Pharmacies, including those within grocery and big-box stores (some will even give you a store gift card for getting the shot)
• Doctor’s office
• Urgent care center
• Student health clinic
• Local health department

Some schools and workplaces also sponsor flu shot events on their premises. The CDC also has a vaccine finder website you can use to find both influenza and coronavirus vaccines in your area.

Depending on your insurance coverage, your flu shot may be free or discounted. If you do have to pay full price for a flu shot, it’s apt to run you $30 to $40. If you can’t get a free flu shot, show your free SingleCare prescription discount card to your pharmacist to get the best deal possible.