Adults also need to be vaccinated from time to time to protect themselves against serious infectious diseases. In fact, some shots are more important for adults than for children. Every year, thousands of older people die needlessly. Flu usually is a mild disease in healthy children, young adults, and middle-aged people. However, it can be life threatening in older adults.
Flu viruses change all the time.
For this reason, you need to get a flu shot every year. To give your body time to build the proper defense, it's important to get a flu shot between September and mid-November, before the flu season usually starts. Although side effects from the flu shot are slight for most people, some soreness, redness, or swelling may occur on the arm where the shot was given. About 5 to 10 percent of people have mild side effects such as headache or low-grade fever, which last for about a day after vaccination. The flu shot is the primary method of preventing and controlling the flu.