The most common type of flu shot is the Trivalent vaccine, which covers three strains of the flu. The Quadrivalent vaccine covers four strains, but there’s not much of it made and it’s intended for immuno-compromised individuals.
The Center for Disease Control says that everybody who is six months and older should get the flu vaccine, unless they have specific vaccine related allergies, like an egg allergy.
There are several options for people looking to get their flu shot this year. In addition to the standard dose Trivalent shot, there is a higher dose form that is approved for people ages 65 and older. Many people, especially children, prefer the nasal spray vaccine, which is approved for people ages two through 49.