Every Question You Have About the Flu Shot, Answered

Including why you really really need to get one this year.

Children Vaccinations in Colorado
Photo: Brent Lewis/Getty Images

Every year, right when we're ready to kick off a month of Halloween and PSL everything, we're bombarded with another season of the un-festive sort: Flu season.

And this year, per the CDC, getting your vaccine "is more important than ever," not only to protect yourself, your family, and your community — but to help reduce the burden on our healthcare system and save medical resources for the care of COVID-19 patients. (A record-breaking 900,000 Americans were hospitalized and more than 80,000 died from the flu in 2017, according to a 2018 report by the National Foundation for Infectious Diseases.)

"Even if you have never had the flu shot, I recommend getting it this year. The flu vaccine can protect you against the flu. To date, we do not have a vaccine to protect you against COVID-19 — and we know that co-infection is possible. Getting both viruses at the same time could be devastating to your health, so I am encouraging all patients to get the flu vaccine this year," says Carmen Teague, M.D., Specialty Medical Director of Internal Medicine at Atrium Health.

Still need some convincing (or just want to clear up some common flu shot myths)? We’ve got you covered. Here’s everything you need to know about this year’s flu shot, including what’s changed, who should get vaccinated, flu shot side effects, and where to go to get your flu shot.

So, How Does a Flu Shot Work?

If you’ve always wondered how the flu shot works, here's the gist: Depending on the type of vaccine you receive, it will contain either "dead" strains of the flu virus, or weakened "live" viruses.

"Injectable flu vaccines are made from either inactivated or partial flu virus and are meant to activate your immune system so that you develop antibodies against the flu virus," explains Nate Favini, M.D., a doctor and the medical lead at Forward, a preventive primary care service. In other words, it triggers your body's natural defense mechanism to be able to fight the actual flu when the time comes.

When Is Flu Season?

The CDC notes that flu season’s timing varies from year to year — it can peak from as early as October to as late as May — and is therefore rather unpredictable. Of course, add a pandemic into the mix and there are even more unknowns than usual.

"Typically though, flu season starts in late November and tends to have small spikes after holiday travel at the end of November and the end of December," Dr. Teague says. Last year, the largest spike occurred in late February, she adds.

"The timing is expected to be the same as previous years," says Jake Deutsch, M.D. founder of Cure Urgent Care, adding that "we’re already seeing positive tests for the flu."

There is no confirmed flu activity as of yet according to the CDC, but the organization will release weekly forecasts to help reduce the spread.

When Is the Best Time to Get a Flu Shot?

Like last year, the CDC still recommends that everyone get their flu shot by the end of October. Why not earlier? "February is the most common month for flu outbreaks, and immunity to the flu wanes about 10 percent each month following vaccination," explains David Cutler, M.D., a family medicine physician at Providence Saint John’s Health Center. In other words, if you get your shot in August, it could leave you with reduced protection later in the flu season.

While there's no such thing as getting vaccinated 'too late' — as long as flu viruses are circulating, vaccination should continue, even in January or later — docs caution against putting it off this year. "The demand will be greater this year due to the pandemic and the possible lack of availability later on in the season," Dr. Deutsch says. "Because it takes several weeks for immunity to set in, waiting longer isn’t a good idea."

TL;DR: Now that we've hit September and flu shots are widely available, docs say you should go ahead and get your flu shot as soon as you can.

Who Needs the Flu Vaccine?

The short answer: everyone who is six months or older. There are only a few rare exceptions, according to the CDC, including if you have an allergy to the flu vaccine or any ingredients included in it. Luckily, this is extremely rare, Dr. Favini says, “with only about one in 1 million people having a severe allergic reaction after receiving a vaccine.”

If you are pregnant or have a compromised immune system, it doesn't mean the flu shot is off the table, but it does mean you'll want to make sure you're sticking to a "killed" vaccine — found in the traditional flu shot.

You’ll also want to chat with your doctor before getting the vaccine if you have ever had Guillain-Barré Syndrome, a rare but serious autoimmune disorder.

What About the Nasal Spray Flu Vaccine?

In addition to the traditional flu shot, there's another option available for healthy, non-pregnant people who are 2 to 49 years old: The nasal spray flu vaccine, which is administered just like an allergy nasal spray. Although it's been around for a few years, the CDC gave its seal of approval last year as an effective alternative to the traditional flu shot for the needle averse.

One important note: there's evidence that it's not as effective as the standard vaccine, says Dr. Teague. "I prefer the injection because [the nasal spray] may not actually be as absorbed as we hope — and could diminish the point of getting the vaccine," seconds Dr. Deutsch.

Also, since it's a "live" rather than a "killed" vaccine, it should also be avoided by anyone who is severely ill, has an immune disorder, or who cares for someone who is severely immunocompromised. You should also take precautions if you have asthma or any other underlying health condition, such as lung, kidney, or heart disease.

The CDC notes that, while age and health status are a factor in deciding the type of vaccine an individual should get, the important thing is simply getting one in the first place.

Do I Really Need to Get a Flu Shot Every Year?

The reason you need a flu shot every year is because the flu virus morphs and changes every year (and the vaccine is updated accordingly).

Plus, there's some evidence that getting a flu shot every year may have a cumulative effect. In one 2017 study, researchers found that the flu shot’s effectiveness may be influenced by vaccines from prior seasons. And in a 2018 study published in the Canadian Medical Association Journal, researchers found that people 65 and older — one of the most vulnerable populations to the effects of influenza — who had repeat vaccines were twice as able to fight the most severe complications related to the flu, including death.

One more time for the people in the back: "It’s absolutely more important to get the flu shot this year — everything has changed this year because of COVID," Dr. Deutsch says.

Should I Still Get the Flu Shot If I'm Sick?

You’ve probably heard that if you’re feeling less than 100 you should skip the flu shot, but this is one major flu shot myth docs want to de-bunk.

“If you have a mild cold or are a little under the weather, you can still get the shot,” Dr. Favini says.

The exception: If you also have a fever. “The concern is that your immune response to the vaccine might not be as strong as needed to boost your immunity, because you’re already fighting another infection,” he says. “In those cases, it’s best to wait until you’re feeling better before getting the shot.”

Are There Flu Shot Side Effects?

It’s true: You might experience some side effects as a result of getting the flu shot, which can include soreness, redness, and/or swelling in the area where the shot was administered, headache, fever, nausea, and muscle aches.

While these symptoms will resolve on their own, the CDC notes that you should seek emergency care if you begin to experience any of the following: a high fever, difficulty breathing, wheezing, swelling around the eyes or lips, hives, paleness, weakness, dizziness and/or a rapid heartbeat.

Overall, flu shot side effects are generally mild — and no, it's not possible for the shot to 'give you the flu.' “It’s common to experience mild aches, fever, or headache after getting the shot, but that’s considerably better than getting the actual flu," Dr. Favini emphasizes.

How Effective Is the Flu Shot Anyway?

Getting the flu shot can reduce your risk of getting the flu by 30 to 60 percent, depending on the strains that are circulating during a season. In one 2018 study, researchers discovered that from 2012 to 2015, adults who got the flu shot saw a 37 percent reduced risk of being admitted to the hospital with the flu.

It's true that a person's age and health can impact the overall effectiveness of the vaccine — and it isn't a sure-fire guarantee you won’t get the flu. That's because it’s tough to create a vaccine well-matched to the exact strains of the virus that will circulate during a specific flu season.

But just because the flu vaccine isn’t 100 percent effective doesn’t mean you should skip it — it's simply the best way to protect yourself and everyone around you.

“Getting the flu shot is the smart thing to do for your own health — many people don’t realize that even healthy, young adults can get sick to the point of hospitalization or even death,” Dr. Favini says. “Beyond that, getting vaccinated contributes to what’s called 'herd immunity' — the more people that get vaccinated, the less likely a severe epidemic becomes.”

He added: “This helps protect more vulnerable people like young babies who can’t get the flu shot and seniors who are more likely to become very ill with the flu. Your shot could save the life of someone you know.”

So, Where Can I Get a Flu Shot?

“The flu vaccine for the winter is available now at your primary care physician’s office, local pharmacies, and perhaps through your work or other community vaccine programs,” Dr. Cutler says.

Check out the CDC’s flu vaccine finder where all you have to do is type in your zip code for a list of places that offer the flu shot in your area.

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