Vaccine adverse events: separating myth from reality.

Vaccines have turned many childhood diseases into distant memories in industrialized countries. However, questions have been raised about the safety of some vaccines because of rare but serious adverse effects that have been attributed to them. Pain, swelling, and redness at the injection site are common local reactions to vaccines. Fever and irritability may occur after some immunizations. Currently, no substantial evidence links measles-mumps-rubella vaccine to autism, or hepatitis B vaccine to multiple sclerosis. Thimerosal is being eliminated from routine childhood vaccines because of concerns that multiple immunizations with vaccines containing this preservative could exceed recommended mercury exposures. Family physicians should be knowledgeable about vaccines so that they can inform their patients of the benefits of immunization and any proven risks. If immunization rates fall, the incidence of vaccine-preventable illnesses may rise.