Influenza is a viral infection. Symptoms include fever, cough, sore throat, runny or stuffy nose, headache, muscle aches, and extreme fatigue. Most people who get an influenza infection recover fully within 1-2 weeks, but some people develop serious and possible life-threatening complications. While the body is busy fighting off the flu, it may be less able to resist a second infection.

Older people with chronic illnesses run the greatest risk of getting secondary infections, especially pneumonia. In an average year, flu leads to about 20,000 deaths nationwide and many more hospitalizations, mostly in people over 65. Pneumonia that results from influenza is the sixth leading cause of death in the United States. Medicare covers both flu shots and pneumococcal vaccines, which prevent serious infections including some forms of pneumonia. However, in 1995, only 58% of those eligible received the vaccine.

No vaccine gives complete protection, and the flu shot is no exception. In older people and those with certain chronic illnesses, the flu shot often is less effective in preventing flu than in reducing symptoms and the risk of serious illness and death. Studies have shown that the flu shot reduces hospitalizations by about 70% and death by about 85% among older people who are not in nursing homes. The percentages are slightly lower among nursing home residents.

The flu shot is made from killed flu viruses, which cannot cause the flu, but it takes about 10-14 days to begin its full protection. Someone who develops a flu-like illness shortly after vaccination could have one of many other infections, including the common cold virus or flu virus they were exposed to before receiving the vaccine. Since viruses for flu vaccines are grown in eggs, people who have a severe allergy to eggs should not get the flu shot as it may cause a serious reaction. Flu shots do not cause side effects in most people. Less than one-third of those who get the shot have soreness, redness or some swelling on the arm where the shot is given, and about 5-10% of people may get a mild headache or a low-grade fever for about a day after vaccination. Although, in the U.S., flu season usually occurs from November until April, most people get the flu between late December and early March. The best time to get your flu shot is between September and mid-November. Flu viruses change all the time. Every year the flu shot is updated to include the most current flu virus strains, so influenza vaccinations must be given annually. –