Vaccination is the single best way to prevent the flu. A decision not to immunize is a decision that could put yourself and others who come into contact with you at risk of a disease that could be dangerous or deadly.
Get the vaccine even if you think you had the flu.
If you were ill in the spring of 2009, but do not know for certain if you had 2009 H1N1 flu infection, you should get vaccinated. If a specific kind of lab test, called PCR, confirmed you had 2009 H1N1 flu, you should have some immunity against the 2009 H1N1 flu and can choose not to get vaccinated. However, vaccination of a person with some existing immunity to the 2009 H1N1 virus will not be harmful. For more information on flu tests, see Influenza Diagnostic Testing During the 2009-2010 Flu Season.
Any immunity from 2009 H1N1 flu or vaccination will not provide protection against seasonal flu. If you want protection from seasonal flu, you should still get the seasonal flu vaccine. Each seasonal influenza vaccine contains 3 flu viruses: 1 A (H3N2) virus, 1 regular seasonal A (H1N1) virus – not the 2009 H1N1 virus – and 1 B virus. The viruses in the vaccine change each year based on international surveillance and scientists’ estimations about which types of viruses will circulate in a given year. The protection that you received from a past year’s vaccine or infection won’t protect you against the seasonal flu circulating this year.