Unfortunately, it is possible to get the flu even if you had the flu shot. The effectiveness of the shot depends mainly on two things: the health of the person getting the shot, and the match of the viruses in the vaccine with those causing the flu that season. Before each flu season starts, the world’s major health organizations study the pattern of viruses present across the globe. They then recommend which viruses should be included in the next year’s flu vaccine. This year’s vaccine (2012) contains three separate viruses.
It is also important to know that there are many other viruses besides the flu that circulate during the flu season. The flu shot will not prevent you from getting any of these other viruses.
If you have flu symptoms, contact your doctor. He or she will be able to tell you if the flu is already present in your state. If so, they may suggest an antiviral medication or other treatments to help with your symptoms.
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