Vaccine FAQ
02 10 07 - 12:05
Vaccine Benefits, Vaccine Risks: 9 Basic Questions Answered
Oct. 1, 2007 -- What are the real benefits -- and the real risks -- of U.S. childhood vaccines? Do vaccines cause autism? Why do some vaccines still contain the controversial, mercury-based compound thimerosal?
WebMD asked Anne Schuchat, MD, director of the CDC's National Center for Immunization and Respiratory Diseases, to answer these and other basic but vital vaccine questions.
1. What are vaccines?
Vaccines help our bodies make protection against life-threatening infectious diseases.
[Note from WebMD Medical Editor Louise Chang, MD:
When a germ invades the body, the immune system recognizes it as a foreign invader. This sets off a cascade of events. The immune system makes antibodies, which are specialized molecules that stick to the invader and either inactivate it or mark it for destruction. Specialized immune cells also seek out and destroy germs and cells in which germs are multiplying. Other immune cells remember the germ so the next time a germ of the same kind tries to invade the body, the immune system will be able to mount an immediate response.
Vaccines offer a shortcut to immunity by raising protective immune responses before a germ invades. This gives the body a crucial head start in preventing or lessening the severity of a dangerous infection.]
2. Why are some vaccines given a few times in childhood, and others given every year?
Before a vaccine is licensed, it is tested to understand how well it can protect. Some vaccines need multiple doses to provide protection, and some need boosters five or 10 years later to make sure the protection stays active. Some vaccines given in childhood wear off as a child becomes a teen, so a new vaccination is needed.
The vaccine that has to be given every year is the flu vaccine. That has to be given every year because the flu viruses change quickly. So a totally new vaccine is made each year.
(Do you think the MMR vaccine causes autism? WebMD’s Rod Moser, PA, PhD, says, "No!" Find out why on his blog.)
3. Can vaccines cause the diseases they are supposed to prevent? Every year you hear people say, "I got my flu shot and then I came down with the flu."
Flu vaccine does not cause the flu. Many vaccines do not provide 100% protection, but they decrease the chances of getting an infection. Even so, they don't reduce the chances to zero. Sometimes, even a person who is vaccinated can get an infection the vaccine was supposed to prevent. But the vaccines used today don't cause the diseases they are supposed to prevent.