The single best way to protect against the flu is to get vaccinated each year.
There are two types of vaccines:
- The “flu shot”—an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. The flu shot is approved for use in people older than 6 months, including healthy people and people with chronic medical conditions.
The nasal-spray flu vaccine — a vaccine made with live, weakened flu viruses that do not cause the flu (sometimes called LAIV for “live attenuated influenza vaccine” or FluMist®). LAIV (FluMist®) is approved for use in healthy* people 2-49 years of age† who are not pregnant.
Each vaccine contains three influenza viruses-one A (H3N2) virus, one A (H1N1) virus, and one B virus. The viruses in the vaccine change each year based on international surveillance and scientists’ estimations about which types and strains of viruses will circulate in a given year.
About 2 weeks after vaccination, antibodies that provide protection against influenza virus infection develop in the body. More of this article here…
Another good link is: http://www.hc-sc.gc.ca/iyh-vsv/diseases-maladies/flu-grippe_e.html#mi