Frequently Asked Questions

People infected with seasonal and 2009 H1N1 flu shed virus and may be able to infect others from 1 day before getting sick to 5 to 7 days after. This can be longer in some people, especially children and people with weakened immune systems and in people infected with the new H1N1 virus.

No, a flu shot cannot cause flu illness. The viruses contained in flu shots are inactivated (killed), which means they cannot cause infection. Flu vaccine manufacturers kill the viruses used in the vaccine during the process of making vaccine, and batches of flu vaccine are tested to make sure they are safe. In randomized, blinded studies, where some people got flu shots and others got saltwater shots, the only differences in symptoms was increased soreness in the arm and redness at the injection site among people who got the flu shot. There were no differences in terms of body aches, fever, cough, runny nose or sore throat.

How well the seasonal flu vaccine works depends on how well the match is between the seasonal influenza (flu) vaccine and the types of seasonal flu viruses that are circulating that year. Scientists try to predict what strains (types) of flu viruses are most likely to spread and cause illness each year to put into the vaccine. Past studies have shown in years when the vaccine viruses and circulating viruses are well-matched, the vaccine can reduce the chances of getting the flu by 70% to 90% in healthy adults. The vaccine may be somewhat less effective in elderly persons and very young children, but vaccination can still prevent serious complications from the flu.

No. 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, before the flu season really gets under way.

Some people should be vaccianted without first consulting a physician. They include:

• People who have a severe allergy to chicken eggs
• People who have had a severe reaction to a flu vaccination in the past
• People who developed Guillian-Barre syndrome (GBS) within 6 weeks of getting a flu vaccine previously
• Children less than 6 months of age
• People who have a moderate or severe illness witha  fever should wait to get vaccinated until their symptoms lessen

In general, anyone who wanted to reduce their chances of getting seasonal flu can get vaccinated.  However, certain people should get vaccinated each year either because they are at high risk of having serious flu-related complications or because they live with or care for high risk persons.

People who should get a seasonal flu vaccination each year include:

• Children aged 6 months up to their 19th birthday
• Pregnant women
• People aged 50 or older
• People of any ag with certain chronic medical conditions
• People who live in nursing homes an dother long-term care facilities
• People who live with or care for those at high risk for complications from flu, including:
  • Health care workers
  • Household contacts of persons at high risk for complications from the flu
  • Household contacts and out of home caregivers of children less than 6 months of age