According to a just-released study by the non-profit Institute of Medicine, vaccines are rarely responsible serious side effects -- and when they are, it's in children whose immune systems are already compromised.
Researchers looked at over 1,000 peer-reviewed studies on vaccination, and found that parents don't have to worry about the most commonly feared side effect of vaccines, autism. According to the New York Times
“The M.M.R. vaccine doesn’t cause autism, and the evidence is overwhelming that it doesn’t,” Dr. Ellen Wright Clayton, the chairwoman of the panel, assembled by the Institute of Medicine, said in an interview. She was referring to a combination against measles, mumps and rubella that has long been a focus of concern from some parents’ groups.
The panel did conclude, however, that there are risks to getting the chickenpox vaccine that can arise years after vaccination. People who have had the vaccine can develop pneumonia, meningitis or hepatitis years later if the virus used in the vaccine reawakens because an unrelated health problem, like cancer, has compromised their immune systems.