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Influenza (Flu)

Note: The content on this page is current but will likely change in summer or early fall to reflect a possible change to the U.S. influenza vaccination policy for 2016-2017. Once this change is approved and published by the Centers for Disease Control and Prevention, the content on this website will be updated before the 2016-2017 influenza season.

Vaccines to Prevent Influenza (Flu)

Vaccination & Vaccine Safety

Flu vaccine infographicEveryone six months of age and older should get the flu vaccine. Seasonal flu vaccines have a very good safety track record.

  • The flu vaccine is available by shot or nasal spray.
  • Get your flu shot or spray as soon as the vaccine is available in your area.
  • It is especially important to get the vaccine if you, someone you live with, or someone you care for is at high risk of complications from the flu.
  • Mild side effects such as soreness, headaches, and fever are common side effects of the flu vaccine.
  • If you experience a severe reaction such as difficulty breathing, hives, or facial swelling, seek medical attention immediately.

Where can I get the Vaccine?

Use the Flu Vaccine Finder to find a flu vaccine location near you this flu season. The 2015-2016 vaccine is now available.

How Effective is the Flu Vaccine?

The flu vaccine is the best protection against the flu this season. Flu vaccination can reduce flu illnesses, doctor visits, and missed work and school due to flu, as well as prevent flu-related hospitalizations and deaths.

When should I get the Vaccine?

Get the vaccine soon after it becomes available in your area, ideally by October, to ensure that you are protected before flu season begins. However, as long as flu viruses are circulating, vaccination should continue throughout the flu season. Flu season usually peaks between December and February, but activity can last as late as May. Early immunization is the most effective, but it is not too late to get the vaccine in January or beyond.

How should I get the Vaccine?

There are two different types of flu vaccines, trivalent and quadrivalent.

Trivalent vaccines protect against two influenza A viruses (an H1N1 and an H3N2) and an influenza B virus. Trivalent vaccines are available in:

  • Standard-dose trivalent shots (IIV3), approved for use in people six months and older. (Most flu shots are given with a needle. One flu vaccine also can be given with a jet injector, for persons 18 through 64 years old).
  • Intradermal trivalent shot, which is injected into the skin instead of the muscle and uses a much smaller needle than the regular flu shot, approved for people 18 through 64 years old.
  • High dose trivalent shot approved for people 65 years or older.
  • A trivalent shot containing virus grown in cell culture, which is approved for people 18 or older. Recombinant trivalent shot that is egg-free, approved for people 18 years or older.

Quadivalent vaccines protect against two influenza A viruses and two influenza B viruses. Quadrivalent vaccines are available in:

  • Quadrivalent flu shot. Different vaccines are approved for different age groups. There is a quadrivalent flu shot that can be given to children as young as six months of age. Other quadrivalent flu shots are approved for people three years and older.
  • Nasal spray, approved for healthy people from 2-49, who do not have contraindications to the nasal spray vaccine.

How Long is my Flu Vaccination Good for?

A flu vaccine is needed every season for two reasons. First, the body’s immune response from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, the formulation of the flu vaccine is reviewed each year and sometimes updated to keep up with changing flu viruses. For the best protection, everyone six months and older should get vaccinated annually.

Does the Flu Vaccine Work Right Away?

It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. In the meantime, you are still at risk for getting the flu. That's why it's better to get vaccinated early in the fall, so you are protected before flu begins spreading in your community.

Is the Vaccine Safe?

Seasonal flu vaccines have a very good safety track record. Although there are possible side effects to vaccination, the Centers for Disease Control and Prevention and the Food and Drug Administration closely monitor the safety of seasonal flu vaccines.

Should I get the Flu Vaccine if I’m not Feeling Well?

If you are sick with a fever, you should wait until your fever is gone before getting a flu shot. However, you can get a flu shot if you have a respiratory illness without a fever, or if you have another mild illness.

The nasal-spray flu vaccine can be given to people with minor illnesses, such as:

  • Diarrhea
  • Mild upper respiratory tract infection, with or without a fever.

If you have nasal congestion, you should consider waiting to get the nasal-spray flu vaccine. Nasal congestion may limit the vaccine's ability to reach the nasal lining.

Are there Side Effects?

There are different side effects that may be associated with getting a flu shot or a nasal spray flu vaccine.. Possible mild side effects of the flu shot include:

  • Soreness, redness, and swelling at the injection site
  • Fainting, mainly in adolescents
  • Aches
  • Fever (low grade)
  • Nausea

Possible mild side effects of the nasal spray include:

  • Runny nose
  • Wheezing
  • Headache
  • Vomiting
  • Muscle aches
  • Fever

Serious side effects usually begin within a few minutes to a few hours after receiving the shot. Possible serious side effects of vaccination include:

  • Difficulty breathing
  • Hoarseness
  • Swelling around the eyes or lips
  • Hives
  • Paleness
  • Weakness
  • Racing heart
  • Dizziness
  • Behavior changes
  • High fever

If you experience any of these reactions, seek medical attention immediately.

How can I Report a Serious Reaction to the Vaccine?

Contact your health care provider immediately if you have a serious reaction to the flu vaccine. Your health care provider should report your reaction to the Vaccine Adverse Event Reporting System (VAERS). You can also file a report yourself. All serious reactions should be reported, even if you aren’t sure it was caused by the flu vaccine. VAERS uses this data to help identify serious reactions that may need further investigation.

If your reaction results in a serious injury, you may qualify for compensation from the Vaccine Injury Compensation Program (VICP). VICP provides compensation for vaccine-related injury or death claims for covered vaccines given on or after October 1, 1988.

Can I get the Flu from the Vaccine?

No, you cannot get the flu from the flu shot or the nasal spray. The flu shot contains inactivated (killed) flu viruses that cannot cause illness. The nasal spray contains weakened live viruses. The weakened viruses only cause infection in the cooler temperatures found in the nose. The viruses cannot infect the lungs or other areas in the body where warmer temperatures exist.

Will I Need to Pay for the Vaccine?

Most health insurance plans cover the cost of vaccines, but you should check with your insurance company before visiting your health care provider. Under the Affordable Care Act, many insurers are required to cover certain preventive services, like the flu vaccine, at no cost to you.

If you do not have insurance or if it does not cover vaccines, help is available.

Is there anyone who should not get the Vaccine?

Talk to your health care provider about vaccination if you have:

  • A severe allergy to chicken eggs or any of the ingredients in the vaccine.
  • A history of severe reaction to a flu vaccination.
  • A moderate-to-severe illness with a fever (you should wait until you are better to get the vaccine).
  • Some people with a history of Guillain–Barré Syndrome (a severe paralytic illness, also called GBS) should not get this vaccine. Talk to your doctor about your GBS history.

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