Inactivated or the “flu shot” is given by injection into the muscle There are three different flu shots available:
US FDA's statement on injector jet influenza vaccinations
The ability of a flu vaccine to protect a person depends on the age and health status of the person getting the vaccine, and the similarity or “match” between the viruses in the vaccine and those in circulation. For more information about vaccine effectiveness see How Well Do Flu Vaccines Work?
Vaccine Side Effects (What to Expect)
Different side effects can be associated with the flu shot and LAIV. The following information is from the CDC:
The flu shot: The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. Some minor side effects that could occur are:
Soreness, redness, or swelling where the shot was given
Fever (low grade)
If these problems occur, they begin soon after the shot and usually last 1 to 2 days. Almost all people who receive influenza vaccine have no serious problems from it. However, on rare occasions, flu vaccination can cause serious problems, such as severe allergic reactions. As of July 1, 2005, people who think that they have been injured by the flu vaccination can file a claim for compensation from the National Vaccine Injury Compensation Program (VICP).
More information about the safety of flu vaccines is available at Influenza Vaccine Safety.