GoodRx Guide
Flu Vaccines
Comprehensive information for you or a loved one — including treatment options and discounts on popular medications.
The flu is a contagious respiratory illness caused by influenza viruses. Most people with the flu experience symptoms, such as fever, cough, and body aches.
But some people can have complications from the flu. Your at higher risk for flu-related complications if you:
Are under age 2 or over age 65
Are pregnant
Have a weakened immune system
Have health conditions, like heart disease, respiratory disease, or diabetes
One of the best ways to prevent the flu is by getting an annual flu vaccine. The flu shot is available for anyone 6 months and older.
What is the flu shot?
The flu shot is another name for the flu vaccine. It’s called a “shot” because most flu vaccines are given as an injection. But there’s also a nasal spray version that you breathe in instead of getting as a shot.
The flu vaccine is updated each year because influenza viruses change over time. Each season, experts track which strains are spreading and update the vaccine to target the strains most likely to circulate during the new flu season.
For the 2025-2026 flu season, all flu vaccines in the U.S. protect against three different types of flu viruses:
Two influenza A viruses (H1N1 and H3N2)
One influenza B virus (Victoria lineage)
Who should get the flu shot?
Almost everyone ages 6 months and older can get a yearly flu shot, even if they’re healthy.
Here are the only exceptions:
If you’re currently sick with a fever, wait to get a flu shot. This doesn’t mean you can’t get the flu shot at all. But talk to a healthcare professional first. They may recommend that you wait until your current symptoms have passed.
If you have a history of Guillain-Barré syndrome (GBS), talk with a healthcare professional before getting the flu shot.
If you have a severe, life-threatening allergy to one of the vaccine ingredients (not eggs) or to the vaccine itself, talk with a healthcare professional about how to best protect yourself.
When should you get a flu shot?
In the U.S., flu season can start as early as October. The best time to get the flu shot is at least 2 weeks before the flu starts circulating in your community — preferably by the end of October. But you can get vaccinated later in the flu season, too. It's almost never too late to get your flu shot.
It takes about 2 weeks after you get the flu shot for you to be protected against the flu. Everyone needs a new flu vaccine every year, since immunity wears off after about 6 months.
Keep in mind: Some children might need 2 doses given at least 4 weeks apart to be fully protected. This includes children between ages 6 months and 8 years who’ve never had a flu vaccine before.
How does the flu vaccine work?
The flu vaccine trains your immune system to fight the flu virus.
Your immune system protects you by recognizing proteins on germs that don’t belong in your body. When it detects these proteins, it begins producing antibodies designed to target and neutralize germs.
It takes time to build those antibodies the first time you’re exposed to a new germ. During that time, you'll feel sick. After your immune system fights off the germs, some immune cells remain as memory cells. They can respond quickly if the same germ enters your body again.
Vaccines use this same process. They expose your immune system to a harmless piece or weakened form of a virus or bacteria. This allows your immune system to build immune memory before you get sick. If you’re exposed later, your immune system can respond much more quickly, producing antibodies right away instead of starting from scratch. This can keep you from getting sick. And if you do get sick, you'll likely have a more mild illness.
How effective is the flu vaccine?
Flu vaccine effectiveness varies from year to year. That’s because the strains included in the vaccine don’t always perfectly match the strains that end up circulating in a community.
Predicting which flu strains to target is challenging because the virus changes quickly. Experts have to make their best estimate months before flu season begins, since manufacturers need time to produce and distribute the vaccine. If the virus evolves in unexpected ways after those decisions are made, the match may not be exact.
Most years the flu shot is between 40% and 60% effective. For example, in 2024-2025 it was about 42% effective. This means that people who got vaccinated last year were 42% less likely to get sick with the flu, compared with people who didn’t get the vaccine. But if they did get sick, they were less likely to get severely ill compared with people who didn't get the vaccine.
Types of flu vaccines
There are several different types of flu vaccines:
Live attenuated influenza vaccine (LAIV): These flu vaccines are made with tiny amounts of weakened live virus. The LAIV may not be the safest option for people with weakened immune systems.
Inactivated influenza vaccine (IIV): These vaccines are made with varying amounts of dead virus.
Recombinant influenza vaccine (RIV): These vaccines are made with synthetic (lab-made) virus.
What is in the flu shot?
The flu vaccine is made of tiny amounts of flu virus along with other ingredients that help to stabilize the vaccine, or make it more effective. A flu shot may contain:
Adjuvants: These are ingredients that help boost your vaccine response. Adjuvanted vaccines can help people ages 65 and older have a stronger immune response to the flu shot.
Stabilizers: These are sugars and proteins that help to extend the vaccine’s shelf life.
Thimerosal (ethylmercury): This is a naturally occurring element that’s been used safely as a preservative for decades. It’s used to keep germs from growing in multi-dose vaccine vials.
Formaldehyde: This keeps viruses from growing inside the vaccine. The amount in the flu shot is very small and not dangerous. In fact, your body makes much more formaldehyde on its own than what’s included in vaccines.
Antibiotics: These keep bacteria from growing in the vaccine during production. The amount of antibiotics in vaccines is small or undetectable. Antibiotics that many people are allergic to — like penicillin — aren’t used in vaccines.
Egg protein: This is found in some flu vaccines. Most people who have egg allergies can still get a flu shot.
Latex: There’s no latex in the vaccine liquid. But latex may be used for the stopper on the vaccine vial or syringe. Latex allergic reactions from a flu shot are rare.
What are common side effects of the flu vaccine?
Some people may have flu-like symptoms after getting a flu vaccine. These symptoms are usually mild and can include:
Fatigue
Fever
Body aches
Headaches
These are normal side effects. These symptoms are a sign your body is making antibodies. They usually go away in 1 to 2 days. Having these symptoms doesn’t mean you’re getting the flu. You can’t get the flu from the flu shot.
Flu vaccines for older adults
Different flu vaccines are approved for different age groups. You can get any flu shot that's approved for your age group.
Experts recommend that people ages 65 and older choose one of the following:
Fluzone High-Dose (high-dose IIV): This contains a higher dose of virus antigen. It’s meant to give a better immune response against the flu to people ages 65 and older.
Flublok (RIV): This is a lab-made flu vaccine. There’s some evidence that it may be more effective in older adults than standard inactive influenza vaccines (IIVs).
Fluad (adjuvanted IIV): This is an inactivated influenza vaccine (IIV) with an added adjuvant. The adjuvant may help your immune system respond to the vaccine. There’s some evidence that it might be especially helpful for older adults.
Where to get a flu vaccine
The most convenient place to get your annual flu vaccine may be your local community pharmacy. Places like CVS, Walgreens, and other retail pharmacies typically offer flu shots as soon as they’re available. Contact your local pharmacy or visit their websites for more information on whether you need to make an appointment.
You can also get your flu shot at retail health clinics, such as CVS MinuteClinic. This option provides an extra layer of privacy, as you’ll be vaccinated in a private room. Urgent care centers and your primary care provider’s office are other options to consider for your flu vaccine.
If you need or prefer a certain vaccine type, such as the recombinant or nasal spray vaccines, contact your vaccination location ahead of time. They may need to order it for you.
Does insurance cover flu vaccines?
Most insurance plans fully cover flu vaccines. This includes state- and federally funded plans, such as Medicare and Medicaid.
Some plans may require you to receive your vaccine in a certain location. For instance, your plan may only cover the flu shot if you get it at a community pharmacy. Contact your plan’s member services number on your insurance card for more details.
If your insurance doesn’t cover the flu vaccine or you’re uninsured, there are ways to save. GoodRx can help lower the cost of flu vaccines at community pharmacies. And there are various programs available that provide free or low-cost flu vaccines to people who meet certain requirements.
Frequently asked questions
No, the flu shot doesn’t cause the flu. No matter what type of flu vaccine you get, it won’t give you the flu. That’s because flu vaccines only contain dead or weakened viruses — and sometimes just fragments. There’s nothing in the flu shot that can cause the flu.
There is no strong evidence that the flu shot causes autism spectrum disorders (ASD). There’s no scientific evidence to support the claim that thimerosal, a preservative used in some vaccines, causes ASD.
No, the flu vaccine doesn’t cause Alzheimer’s dementia. In fact, research suggests that regular flu shots could actually protect against Alzheimer’s dementia.
The influenza vaccine was developed in the 1930s and 1940s. It was first made available to the general public in 1945.
References
Alzheimer’s Association. (2020). Flu, pneumonia vaccinations tied to lower risk of Alzheimer’s dementia.
Centers for Disease Control and Prevention. (2022). Adjuvanted flu vaccine.
Centers for Disease Control and Prevention. (2024). Fluzone high-dose seasonal influenza vaccine.
Centers for Disease Control and Prevention. (2024). Guillain-Barré syndrome (GBS) and vaccines.
Centers for Disease Control and Prevention. (2024). Misconceptions about seasonal flu and flu vaccines.
Centers for Disease Control and Prevention. (2024). People at increased risk for flu complications.
Centers for Disease Control and Prevention. (2024). Thimerosal and vaccines.
Centers for Disease Control and Prevention. (2024). Thimerosal in flu vaccine.
Centers for Disease Control and Prevention. (2024). Who needs a flu vaccine.
Centers for Disease Control and Prevention. (2025). ACIP recommendations summary.
Centers for Disease Control and Prevention. (2025). Types of influenza viruses.
Grohskopf, L. A., et al. (2024). Prevention and control of seasonal influenza with vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2025–26 influenza season. Centers for Disease Control and Prevention.
University of Oxford. (2019). What is a vaccine, and how do vaccines work?
U.S. Department of Health and Human Services. (2022). Vaccine types.
World Health Organization. (n.d.). History of the influenza vaccine.
