What is the flu vaccine?
A vaccine is a type of medicine that prepares the body’s immune system so that it can fight a disease, it has not come into contact with before. Vaccines are designed to prevent disease, rather than treat a disease once you have caught it. The flu vaccine can keep you from getting sick with the flu.
Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are in the vaccine.
There are different forms of the flu, including the "seasonal" flu, the 2009-2010 pandemic H1N1 flu ("swine" flu), and the bird flu ("avian" flu). The flu vaccines that are available now do not protect against bird flu.
There is tendency of flu virus to change year to year. That’s why some years the flu vaccine is more effective than others. And it takes months to make a new vaccine. But even in years when the vaccine is less effective, it still helps prevent some cases of the flu and also helps to prevent serious illness and outbreaks of the flu.
Some people think the flu vaccine doesn't work because they have known people who got flu even when they had taken flu vaccine.
Many people who get flu like symptoms even after getting the flu vaccine does not mean they actually have the flu; they could be having a cold caused by a virus unrelated to the flu virus, so the flu vaccine can't help with that.
Different forms of the flu vaccine