I worked in a medical lab for years and always got them, but don't any more since leaving there. The flu shot contains the virus for known flues from recent years but any virus that has managed to mutate into a new strain will still get you and that means there are still 1000's of those sicknesses flying around at all times. Also, there is a list of additives in the shot, such as eggs, mercury, etc. all in minute quantities, but it's usually the additives that cause a reaction in people. You can't catch the flu from a flu shot because the virus in the flu shot are all dead. But you can catch the flu from going to your doctor's office to get the flu shot because there are other germs there!