Flu shots are vaccines administered annually to prevent influenza, a disease caused by influenza viruses. The composition of flu vaccines varies yearly depending on the circulating influenza virus strains, and regular vaccination is recommended. Flu shots offer high protection against influenza, particularly for infants, those with chronic illnesses, and the elderly; however, administration is at the discretion of a physician.

The recommended timeframe for flu vaccination is before the start of flu season, typically September-October.