Killed (inactivated) vaccines are made from a protein or other part of a virus or bacteria. The flu shot is an example of a killed vaccine. Inactivated vaccines are easier for your health care provider to handle. Most do not require refrigeration, special mixing or shipping requirements. read more
The flu vaccine that is delivered as a nasal spray, rather than as injection, does contain live viruses, but these viruses have been weakened, and so they also cannot cause the flu, according to the CDC. Myth: The flu vaccine may not be safe for pregnant women or babies. read more
The nasal spray flu vaccine does contain live viruses. However, the viruses are attenuated (weakened), and therefore cannot cause flu illness. The weakened viruses are cold-adapted, which means they are designed to only cause infection at the cooler temperatures found within the nose. read more