Flu shot: Your best bet for avoiding influenza

Getting a flu shot often protects you from coming down with the flu. And although the flu shot doesn't always provide total protection, it's worth getting.

By Mayo Clinic Staff

This year's annual flu shot will offer protection against H1N1 flu (swine flu) virus, in addition to two other influenza viruses that are expected to be in circulation this flu season. A vaccine that protects against four strains of the virus will also be available, as will a high-dose flu vaccine for adults age 65 and older.

Influenza is a respiratory infection that can cause serious complications, particularly to young children and to older adults. Flu shots are the most effective way to prevent influenza and its complications. The Centers for Disease Control and Prevention (CDC) recommends that everyone 6 months of age or older be vaccinated annually against influenza.

Here are the answers to common questions about flu shots:

When is the flu vaccine available?

Because the flu vaccine is produced by private manufacturers, its availability depends on when production is completed. For the 2014-2015 flu season, manufacturers have indicated shipments are likely to begin in July or August and continue throughout September and October until all vaccine is distributed. Doctors and nurses are encouraged to begin vaccinating people as soon as flu vaccine is available in their areas.

It takes up to two weeks to build immunity after a flu shot, but you can benefit from the vaccine even if you don't get it until after flu season starts.

Why do I need to get vaccinated every year?

New flu vaccines are released every year to keep up with rapidly adapting flu viruses. Because flu viruses evolve so quickly, last year's vaccine may not protect you from this year's viruses.

After vaccination, your immune system produces antibodies that will protect you from the vaccine viruses. In general, though, antibody levels start to decline over time — another reason to get a flu shot every year.

Who should get the flu vaccine?

The CDC recommends annual influenza vaccinations for everyone age 6 months or older. Vaccination is especially important for people at high risk of influenza complications, including:

  • Pregnant women
  • Older adults
  • Young children

Children between 6 months and 8 years may need two doses of flu vaccine to be fully protected. Check with your child's health care provider.

Chronic medical conditions can also increase your risk of influenza complications. Examples include:

  • Asthma
  • Cancer or cancer treatment
  • Chronic obstructive pulmonary disease (COPD)
  • Cystic fibrosis
  • Diabetes
  • HIV/AIDS
  • Kidney or liver disease
  • Obesity

Who shouldn't get a flu shot?

Check with your doctor before receiving a flu vaccine if:

  • You're allergic to eggs. Some flu vaccines contain tiny amounts of egg proteins. If you have an egg allergy or sensitivity, you'll likely be able to receive a flu vaccine — but you might need to take special precautions, such as waiting in the doctor's office for at least 30 minutes after vaccination in case of a reaction. There are also flu vaccines that don't contain egg proteins, and are Food and Drug Administration (FDA) approved for use in people age 18 and older. Consult your doctor about your options.
  • You had a severe reaction to a previous flu vaccine. The flu vaccine isn't recommended for anyone who had a severe reaction to a previous flu vaccine. Check with your doctor first, though. Some reactions might not be related to the vaccine.

What are my flu vaccine delivery options?

The flu vaccine comes in two forms:

  • A shot. A flu shot contains an inactivated vaccine made of killed virus. The injection is usually given in a muscle in the arm. An in-the-skin (intradermal) vaccine also is available for people 18 to 64 years of age. Because the viruses in this vaccine are killed (inactivated), the shot won't cause you to get the flu, but it will enable your body to develop the antibodies necessary to ward off influenza viruses.
  • A nasal spray. The nasal spray vaccine consists of a low dose of live, but weakened, flu viruses and is approved for use in healthy people 2 to 49 years of age who aren't pregnant. The vaccine doesn't cause the flu, but it does prompt an immune response in your nose and upper airways, as well as throughout your body. The nasal spray vaccine is recommended for healthy children 2 to 8 years when it is available. However, don't delay vaccination if the nasal spray vaccine is not immediately available and the flu shot is.
Oct. 04, 2014 See more In-depth