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Flu Vaccine (Seasonal Influenza Vaccine)

This fact sheet answers frequently asked questions about the flu vaccine.

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There is a new flu vaccine made each year. It protects against the 3-4 strains of influenza expected to circulate for that season. There are many strains of flu and flu viruses are always changing. That constant change means people need a flu vaccine every year to stay protected.

The basics

Who should get the flu vaccine?

Anyone 6 months of age or older should get a flu vaccine. The vaccine is especially important for people at high risk of serious flu complications. High risk people include:

  • Young children
  • Pregnant women
  • People who are 65 years and older
  • People with chronic health conditions like asthma, diabetes, heart, and lung disease

Do I need to get a flu vaccine this year if I was sick with the flu last year?

After recovering from flu, you have protection against only that one strain of flu. But, since there are many other strains, it is possible to get flu again. A flu vaccine is the only way to protect yourself against all 3-4 strains expected to circulate.

Will a person have better immunity if they get the flu rather than the vaccine? 

A person will gain immunity against the flu after getting a vaccine or in some cases after they recover from the flu. It is important to remember that the flu can cause very serious illness in some people. The risk from getting a vaccine is much less than the risk of getting sick with the flu.

Can a person get flu from the flu vaccine?

No, the flu vaccine cannot give you the flu. The vaccine takes two weeks to provide full protection against the flu. It is important to use other prevention methods such as washing your hands and staying away from those who are sick during that time. Many people confuse the flu with cold symptoms since both flu and cold seasons are at the same time. The best way to protect yourself from illness is by getting the flu vaccine and practicing prevention methods.

Risks and side effects

What are the risks of the flu vaccine?

Most people do not have a problem with the vaccine. Side effects may occur, but severe reactions are very rare. The following are possible side effects that may occur, ranging from mild to severe.

Mild side effects (usually begin soon after the shot and last 1-2 days):

  • A sore arm, swelling, and/or redness at the injection site
  • Sore, itchy red eyes, cough, or hoarseness​
  • Fever, aches, headache, fatigue, itching

Moderate side effects:

  • Getting a flu and pneumonia vaccine at the same time can put young children at risk for seizures caused by fever. Ask your health care provider for more information and tell your doctor if your child has ever had a seizure before getting your child vaccinated.

Severe side effects:

  • Life-threatening allergic reactions to vaccines are very rare. If they do occur, it’s normally within a few minutes to a few hours after getting the vaccine. Minimize the risk by telling your health care provider if you have any severe allergies, including to eggs, or if you have ever had a severe allergic reaction to vaccines.

What should I do in the rare case I have a severe reaction?

Call a health care provider and seek treatment immediately if you have a severe reaction within hours of getting a flu vaccine. Symptoms of a severe reaction include high fever, change in behavior, difficulty breathing,  hives, and feeling weak or dizzy.

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