Do different types of flu viruses hit the population each year?
Different strains of the flu virus mutate over time and replace the older strains of the virus. This is why it’s important to get a flu shot each year to ensure that your body develops immunity to the most recent strains of the influenza virus. According to the CDC, each flu vaccine contains three influenza viruses: one A (H3N2) virus, one A (H1N1) virus, and one B virus. The viruses in a flu shot and FluMist vaccine change each year based on international surveillance and scientists’ estimations about which types and strains of the flu will be most potent that year. About 2 weeks after getting a flu shot or FluMist, antibodies that provide protection against the flu viruses develop in your body.
