When should you get a flu shot? What to know for the 2023-2024 flu season (2024)

When should you get a flu shot? What to know for the 2023-2024 flu season (1)

Flu shots for the United States' 2023-2024 influenza season are now available. But when's the best time to get the vaccine, and who should get one?

Here's a rundown of what you need to know about this season's flu vaccines.

Related: Could we ever eradicate the flu?

Who should get a flu shot?

Everyone ages 6 months and older should get a flu shot every season, with rare exceptions, the Centers for Disease Control and Prevention (CDC) recommends.

These exceptions apply to people with severe, life-threatening allergies to specific vaccine ingredients. These potentially allergy-triggering ingredients include gelatin, which is used as a stabilizer in some vaccines, and certain antibiotics, which prevent bacterial contamination during vaccine manufacturing but can linger in very small quantities in some shots post-production, according to the Children's Hospital of Philadelphia.

People who have had a severe allergic reaction to a flu vaccine should not get the same type of vaccine again and should consult a doctor about whether to get a different shot, the CDC says. People with a history of Guillain-Barré Syndrome, a rare paralyzing condition in which the immune system attacks the nerves, should also consult a doctor before getting a flu shot.

But everyone else can assume they should get a shot. Flu shots are especially important for people who are older than 65, younger than 2, pregnant, or have very recently given birth, the CDC states. Note that some children ages 6 months to 8 years are recommended to get two doses of vaccine.

When do you get a flu shot?

Most people should get a flu shot in September or October, before the flu starts circulating widely, the CDC advises. In a typical season, flu cases start to ramp up in late October and peak between December and February. Although it's ideal to get your flu shot early in the season, it's better to get one late than not at all.

Related: The flu shot isn't that effective. Here's why you should still get it.

When should you get a flu shot? What to know for the 2023-2024 flu season (2)

What types of flu shots are available?

There are nine different flu vaccines available this season, including eight that are injected and one that's sprayed up the nose. All the vaccines guard against four influenza virus subtypes: A(H1N1), A(H3N2), a Yamagata lineage influenza B virus and a Victoria lineage influenza B virus.

Speak to a doctor, pharmacist or other health care professional if you have questions about which flu shot is best for you.

Standard-dose, inactivated flu shots: Inactivated flu shots contain influenza viruses that have been "killed" so they can no longer infect cells. They are approved for use in people ages 6 months and older.

Recombinant flu shots: Recombinant flu shots are made using "recombinant technology," which involves using flu virus genetic material to make a protein found on the virus' surface — hemagglutinin (HA). There is one recombinant vaccine available called Flublok Quadrivalent, and it's approved for use in people ages 18 and older. It's one of three vaccine options especially recommended to people 65 years and older.

Nasal spray: The one vaccine that's available as a nasal spray is called FluMist Quadrivalent. It's a live attenuated vaccine, meaning it contains weakened flu viruses that can't cause disease but have not been "killed," like the viruses in inactivated shots. This vaccine is approved for most people ages 2 to 49, but it's not approved for people who are pregnant, have weakened immune systems or have certain other conditions.

High-dose and adjuvanted flu shots: One high-dose flu vaccine and one adjuvanted vaccine, which contains an added ingredient to rev up the immune system, are approved for use in people 65 and older. Along with the recombinant shot, these vaccines are especially recommended for older people because they're more protective in this age group than the standard-dose vaccines. The high-dose shot is called Fluzone High-Dose Quadrivalent and the adjuvanted vaccine is called Fluad Quadrivalent.

Which flu shot should people with egg allergies get?

People with egg allergies can receive any flu shot, egg-based or otherwise, and they don't need a special doctor's appointment to do so, the CDC says. This advice is based on new guidance from a CDC vaccine advisory committee that recently reviewed the available safety data.

When should you get a flu shot? What to know for the 2023-2024 flu season (3)


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Why is the flu shot less effective than other vaccines?

"Egg allergy alone necessitates no additional safety measures for influenza vaccination beyond those recommended for any recipient of any vaccine, regardless of severity of previous reaction to egg," the committee advised. All vaccines should be given in settings where allergic reactions can be recognized and treated quickly, according to the new guidance.

When will we know if the flu shots are a "good match"?

We typically don't know if the flu shots are a "good match" to circulating strains until later in the season. In 2022, for example, officials announced in December that the flu shots were likely a "very good match." A good match would mean that the flu strains included in the vaccines, which are selected ahead of time, will end up being genetically similar to the strains that actually make people sick during the 2023-2024 season.

Vaccine makers decide which flu strains to include in shots for the upcoming season by checking which strains are circulating elsewhere in the world. The Northern Hemisphere and Southern Hemisphere flu seasons happen at different times, so flu virus samples collected in one hemisphere can provide the other clues as to what's to come.

On Sept. 8, the CDC released data on how well the Southern Hemisphere's flu shots performed during their recent season. Data from Argentina, Brazil, Chile, Paraguay and Uruguay showed the shots reduced the risk of flu-related hospitalizations by 52%, overall, and were slightly more protective against the predominant A(H1N1) viruses, specifically. Flu shots available in the U.S. might offer similar protection if these viruses dominate in the Northern Hemisphere's flu season, as well.

Where can you get a flu vaccine?

Use the CDC's VaccineFinder to search for flu shot administration sites in your area.

This article is for informational purposes only and is not meant to offer medical advice.

Editor's note: This article was updated on Sept. 8, 2023 to add new information about the Southern Hemisphere's flu shots. It was first published on Sept. 3.

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When should you get a flu shot? What to know for the 2023-2024 flu season (4)

Nicoletta Lanese

Channel Editor, Health

Nicoletta Lanese is the health channel editor at Live Science and was previously a news editor and staff writer at the site. She holds a graduate certificate in science communication from UC Santa Cruz and degrees in neuroscience and dance from the University of Florida. Her work has appeared in The Scientist, Science News, the Mercury News, Mongabay and Stanford Medicine Magazine, among other outlets. Based in NYC, she also remains heavily involved in dance and performs in local choreographers' work.

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When should you get a flu shot? What to know for the 2023-2024 flu season (2024)


When should I get my flu shot in 2024? ›

You should get vaccinated each year from April onwards to be protected before the influenza season. The peak influenza season is usually June to September in most parts of Australia. However, it is never too late to get the vaccine as influenza can spread all year round.

How effective is the flu shot in 2023 to 2024? ›

CDC panel discusses flu vaccine effectiveness, adds Td vaccine to VFC program. Flu vaccines have been about 59%-67% effective at preventing outpatient medical visits in patients ages 6 months to 17 years during the 2023-'24 flu season, according to data from the Centers for Disease Control and Prevention (CDC).

When is the flu season in 2023-2024? ›

Using the highest weekly values observed from October 1, 2023, through June 15, 2024, CDC assesses this season's severity as: Show keyboard shortcuts.

What month does the CDC recommend getting a flu shot? ›

When should I get vaccinated? For most people who need only one dose of influenza vaccine for the season, September and October are generally good times to be vaccinated against influenza. Ideally, everyone should be vaccinated by the end of October.

When is it best to get a flu shot? ›

It takes up to two weeks to build immunity after a flu shot. You can benefit from the vaccine even if you don't get it until after the flu season starts. It's usually best for people in the United States to get the flu vaccine in September and October. Aim to get it by the end of October.

What new virus is going around 2024? ›

First case of A(H1N2)v virus in the US in 2024

Variant influenza A virus infections are novel influenza A virus infections. A novel influenza A virus is an influenza A virus that is different from seasonal influenza A viruses spreading among people.

What are flu symptoms in 2024? ›

People who are sick with flu often feel some or all of these symptoms:
  • Fever*/feeling feverish or chills.
  • Cough.
  • Sore throat.
  • Runny or stuffy nose.
  • Muscle or body aches.
  • Headaches.
  • Fatigue (tiredness)
  • Some people may have vomiting and diarrhea, though this is more common in children than adults.

When is flu most contagious? ›

People with flu are most contagious during the first 3 days of their illness. Some otherwise healthy adults may be able to infect others beginning one day before symptoms develop and up to five to seven days after becoming sick.

Is flu A or B worse? ›

Type A influenza is generally considered worse than type B influenza. This is because the symptoms are often more severe in type A influenza than in type B influenza. Type A influenza is more common than type B influenza. Researchers suggest that most adults have considerable immunity against type B influenza.

What flu bug is going around 2023? ›

Norovirus, aka stomach flu, in 2023: What to know about symptoms and treatment. Norovirus causes vomiting and diarrhea. Here's what you need to know about symptoms, treatment and prevention. Norovirus, a highly contagious stomach bug that causes diarrhea and vomiting, is on the rise across the United States.

What type of flu is being given in 2023? ›

The 2023-24 flu vaccine will contain protection against two strains of influenza A (H1N1 and H2N3) and two strains of influenza B (from the B/Victoria and B/Yamagata lineages).

What month is flu season the worst? ›

Timing. Seasonal variation in deaths due to influenza or pneumonia in 122 U.S. cities, as a proportion of all causes. In the United States, the flu season is considered October through May. It typically reaches an apex in February, with a seasonal baseline varying between 6.1% and 7.7% of all deaths.

How effective is the flu shot in 2024? ›

March 1, 2024 -- The vaccines for this flu season are 41% to 44% effective in preventing flu-related hospitalization in adults and 52% to 61% effective for children, according to estimates in the CDC's Morbidity and Mortality Weekly Report issued Thursday.

How long does the flu shot take to get in your system? ›

Does the flu vaccine work right away? No. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. That's why it's best to get vaccinated before influenza viruses start to spread in your community.

When is flu season? ›

Most influenza activity usually occurs from October to May in the United States even though influenza viruses have been detected year round. A new influenza season begins the first week of October and goes through the third week in May. However, Texas conducts influenza surveillance year around.

At what age should you get the stronger flu shot? ›

Fluzone High-Dose Quadrivalent is a four-component flu vaccine. It is one of three influenza vaccines (along with Flublok Quadrivalent and Fluad Quadrivalent) that is preferentially recommended for people 65 years and older. This preferential recommendation is new for the 2022-2023 season.

How long does a flu vaccine last? ›

Yes, the flu shot wears off in about six months. The flu shot does not provide long-lasting protection, which is another reason we need to get one every year. When should I get a flu shot? We typically suggest getting the flu shot in the early fall, before the virus starts circulating in the community.

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