Do Vaccines Work?

Vaccines are the best defense we have against serious, preventable, and sometimes deadly contagious diseases. Vaccines are some of the safest medical products available, but like any other medical product, there may be risks. Accurate information about the value of vaccines as well as their possible side-effects helps people to make informed decisions about vaccination.

How Well Do Vaccines Work?

Vaccines work really well. Of course, no medicine is perfect but most childhood vaccines produce immunity about 90 - 100% of the time.What about the argument made by some people that vaccines don’t work that well . . . that diseases would be going away on their own because of better hygiene or sanitation, even if there were no vaccines?That simply isn’t true.
Certainly, better hygiene and sanitation can help prevent the spread of disease, but the germs that cause disease will still be around. As long as germs still exist, they are they will continue to make people sick.All vaccines must be licensed (approved) by the Food and Drug Administration (FDA) before being used in the United States.

A vaccine must go through extensive testing to show that it works and that it is safe before the FDA will approve it. Among these tests are clinical trials, which compare groups of people who get a vaccine with groups of people who get a "control" (e.g, either a different vaccine or placebo).  

A vaccine is approved only if FDA determines that it is safe and effective for its intended use. If you look at the history of any vaccine-preventable disease, you will virtually always see that the number of cases of disease starts to drop when a vaccine is licensed.