Important information on seasonal flu vaccination timing and immunity:

Does getting vaccinated against flu early in the season pose a risk that immunity may wane before the end of the season?

No. Flu vaccination provides protection against the influenza strains contained in the seasonal vaccine for the entire season. Vaccination can begin as soon as vaccine becomes available.

CDC Seasonal Flu Vaccine Update for more information


How long does immunity from influenza vaccine last?

Protection from influenza vaccine is thought to persist for a year or less because of waning antibody and because of changes in the circulating influenza virus from year to year.

Immunization Action Coalition for more information
 

Where can I find more information about how long immunity to flu lasts after vaccination?

For additional information about declining immunity after vaccination, see the studies listed below:

Duration of protection provided by live attenuated influenza vaccine in children

Evaluation of the efficacy of split-product trivalent A(H1N1), A(H3N2), and B influenza vaccines: Reactogenicity, immunogenicity, and persistence of antibodies following two doses of vaccines

Long-term immunogenicity of influenza vaccine among the elderly: Risk factors for poor immune response and persistence


Timing of Vaccination

When should I get the 2011-2012 influenza vaccine?

The Centers for Disease Control and Prevention recommends that people get vaccinated against influenza as soon as vaccine becomes available in their community, but vaccination can take place at any time throughout the influenza season. Influenza seasons are unpredictable, and can begin as early as October.  Since it takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection, the CDC recommends people be vaccinated as soon as vaccine becomes available to ensure that as many people as possible are protected before influenza season begins.


So there is no reason to postpone vaccination until after September or October to make the immunity “last” through the entire influenza season?

CDC recommends that influenza vaccination begin as soon as vaccine becomes available and continue throughout the flu season.

CDC Vaccine Timing Information