Flu shots can help keep you from getting the flu (influenza). The flu virus causes an infection of your air passages that is much like a cold. Unlike most colds, however, the flu often causes fever, muscle aches, and dizziness as well as cold symptoms.
Most people with the flu feel sick for a few days and then get better. However, for some people flu can lead to serious, sometimes life-threatening illness. Complications from flu cause many deaths every year. These deaths usually occur among older adults and people who have chronic health problems, such as heart disease and or severe asthma. So it is important to try to prevent flu and these serious problems by getting flu shots every year
The virus in flu shots has been killed. This means you cannot catch the flu from getting a shot. Getting the shot exposes your immune system to the killed virus. Your body then reacts by making special cells (antibodies) that fight the flu virus.
Flu viruses change each year. The flu vaccine is made to protect against the kinds (strains) of flu virus that experts believe will be infecting people during the next flu season, so the vaccine changes every year as well. It is possible to catch a strain of flu virus that the vaccine does not protect against.
The flu vaccine does not protect against colds and other respiratory infections. You can still get colds or other illnesses that may have symptoms like flu symptoms.
The flus vaccine is usually about 70% effective in preventing flu. If you still get the flu after getting the vaccine, you will likely not get as sick as you would have if you hadn't gotten the vaccine.
It takes about 2 weeks before the flu vaccine can fully protect you against the flu.
All adults and children over 6 months old should get the flu vaccine. This is especially important for people at high risk of serious flu complications, such as:
Vaccination also is important for healthcare workers and other people who live with or care for high risk people to keep them from spreading flu to high risk people.
Most women who are pregnant should wait to get the shot until they have been pregnant for at least 13 weeks. However, if they have other chronic medical problems, it is OK to get the shot earlier in the pregnancy.
Talk with your healthcare provider before getting a flu shot if you:
It’s OK to get the vaccine if you have an upper respiratory infection without a fever (a cold).
Thimerosal is a preservative used in some flu shots. Thimerosal contains mercury and can cause reactions in some people. Thimerosal-free vaccine is available if you are allergic to thimerosal or are concerned about its safety. The nasal flu vaccine does not contain thimerosal.
When you get a flu shot you are injected in the arm with the vaccine.
A nasal spray called FluMist is another way to get the flu vaccine. The nasal spray contains a weakened, live virus and is given only to healthy children over 2 and healthy adults under 50. As with flu shots, you will need a new dose of FluMist every year. Pregnant women, children under 2 years, and people with weakened immune systems, asthma, or some other medical conditions cannot take the nasal spray. People who get FluMist should avoid contact with anyone at risk for at least 1 week to make sure that you don’t spread the live virus to them. If you are thinking about getting FluMist, ask your provider if it is recommended for you.
It is best to get the flu shot every year in October or November just before the start of flu season. However, you can get the flu vaccine anytime during the flu season (October through April) if vaccine is available.
Flu seasons can vary from region to region and continent to continent. If you are at high risk for infection and plan to travel to an area where you might be exposed to the flu, make sure you have an up-to-date flu shot before you go on your trip.
For people who do not have egg or thimerosal allergies, the flu vaccine has infrequent, minor side effects, such as:
If these problems occur, they start soon after the shot. They may last a day or 2.
Serious problems from the flu vaccine, such as severe allergic reactions, are very rare. Signs of a serious allergic reaction can include breathing problems, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness. An allergic reaction may occur within a few minutes to a few hours after the shot. If you are having trouble breathing or throat swelling, call 911.
If you think you are having a reaction to the flu vaccine, call your healthcare provider right away. Tell them when you received the vaccine and what your symptoms are. Ask if your provider needs to see you.
