Myth: Influenza is a minor illness.
Myth: The vaccine causes the flu.
Truth: You can't get the flu by having a flu shot. The flu shot is made of killed virus and therefore cannot cause the flu. And the weakened viruses in the flu nasal spray vaccine can cause symptoms similar to a cold, but they can't cause the flu.
Myth: The vaccine causes unpleasant side effects.
Truth: The vaccine causes no side effects in most people. Earlier vaccines (1940s to 1960s) did have more unpleasant side effects, but this is rare now. And an intradermal flu shot is available. A smaller needle is used, and the vaccine is injected into the skin instead of the muscle to reduce discomfort at the time of the shot.
Myth: The vaccine is ineffective because some people had a flu-like illness after getting a flu vaccine.
Truth: Although getting the vaccine prevents most people from becoming ill with the flu, some people still become infected. This may occur because a person is exposed to the virus before getting a vaccination or before it has taken effect, or because the vaccine does not match the circulating virus closely enough. A mild illness similar to a cold also can be caused by the live, weakened viruses in the influenza nasal spray vaccine. But any illness is usually milder than it would be without having had the vaccine.