There are two types of vaccines that protect against the flu. The &uot;flu shot&uot; is an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. A different kind of vaccine, called the nasal-spray flu vaccine, was approved in 2003. The nasal-spray flu vaccine contains attenuated (weakened) live viruses, and is administered by a nasal sprayer. It is approved for use only among healthy people between the ages of 5 and 49 years. The flu shot is approved for use among people over 6 months of age, including healthy people and those with chronic medical conditions.

When should I get a flu vaccination?

Beginning each September, the flu shot should be offered to people when they are seen by health-care providers for routine care or as a result of hospitalization.

Try to get vaccinated in October or November because flu activity in the United States generally peaks between late December and early March.

You can still benefit from getting vaccinated after November, even if flu is present in your community. Vaccine should continue to be offered to unvaccinated people throughout the flu season as long as vaccine is still available. Once you get vaccinated, your body makes protective antibodies in about two weeks.

Does flu vaccine work right away?

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.

Can I get the flu even though I got a flu vaccine this year?

Yes. The ability of flu vaccine to protect a person depends on two things: 1) the age and health status of the person getting the vaccine, and 2) the similarity or &uot;match&uot; between the virus strains in the vaccine and those in circulation.

Why do I need to get vaccinated against the flu every year?

Flu viruses change from year to year, which means two things. The immunity that is built up from having the flu caused by one virus strain doesn’t always provide protection when a new strain is circulating. Second, a vaccine made against flu viruses circulating last year may not protect against the newer viruses. That is why the influenza vaccine is updated to include current viruses every year.

Another reason to get flu vaccine every year is that after you get vaccinated, your immunity to the disease declines over time and may be too low to provide protection after one year.