evidence: Myth #1: The Flu Shot Can Give You the Flu One of the most prevalent myths is that the flu shot itself causes the flu. This belief stems from a misunderstanding of the vaccine’s composition. The influenza vaccine contains either inactivated flu viruses or, in some cases, a recombinant flu vaccine containing no flu virus at all. While some individuals may experience mild side effects, such as soreness at the injection site, muscle aches, or low-grade fever, neither of these formulations can cause the flu. [...] Some individuals express concerns that the flu shot is a live virus that will cause illness. In reality, the flu vaccine contains either inactivated flu viruses or proteins derived from the flu virus, neither of which can replicate or cause flu infection.