Each year, the seasonal influenza vaccine contains three influenza viruses – one influenza A (H3N2) virus, one seasonal influenza A (H1N1) virus, and one influenza B virus. The influenza viruses in the seasonal flu vaccine are selected each year based on surveillance-based forecasts about what viruses are most likely to cause illness in the coming season. Therefore, each year's seasonal flu vaccine is designed to protect against the influenza viruses expected to cause disease during the upcoming influenza season.
Each year, the seasonal influenza vaccine contains three influenza viruses – one influenza A (H3N2) virus, one seasonal influenza A (H1N1) virus, and one influenza B virus. The influenza viruses in the seasonal flu vaccine are selected each year based on surveillance-based forecasts about what viruses are most likely to cause illness in the coming season. Therefore, each year's seasonal flu vaccine is designed to protect against the influenza viruses expected to cause disease during the upcoming influenza season.
Got mine in September. I've skipped it twice in the past 15 years, and got the worst cases of flu both times. Never had a bad reaction or gotten sick after a flu shot.