CDC recommends a yearly flu vaccine as the first and most important step in protecting against influenza and its potentially serious complications.
While there are many different flu viruses, flu vaccines protect against the 3 or 4 viruses that research suggests will be most common. Three-component vaccines contain an H3N2, an H1N1 and a B virus. Four component vaccines have an additional B virus component. (See Vaccine Virus Selection for this season’s vaccine composition.)