Q. Do vaccines still contain mercury? I've heard that it increases the risk of autism.
A. "Thimerosal, a mercury-containing preservative, is rarely used now in vaccines," says Dr. Neal Halsey. Only a small number of flu vaccines (in multidose vials) contain thimerosal, but most kids will get one without it. Interestingly, a recent Canadian study published in Pediatrics found that rates of autism, which some advocacy groups claim are linked with thimerosal, rose steadily even after thimerosal was removed from all vaccines in Canada. For more info, go to vaccinesafety.edu.
Q. Can a vaccine have any significant side effects?
A. Vaccine side effects have been monitored very carefully since 1990 through the Vaccine Adverse Event Report System. In rare cases, allergic reactions, seizures, and fevers higher than 104 degrees F. have been associated with vaccines. More common are minor side effects like soreness or swelling at the injection site, or a slight fever.
Q. Can my child get a vaccine if he's sick?
A. It's fine if he has a cold, low-grade fever, or even an ear infection, says Dr. Henry Bernstein. Hold off a day or two if your child's fever is above 101 degrees F. or if he isn't acting like himself.
Q. What happens if my child misses a shot or is a bit off schedule?
A. The CDC publishes a special "catch-up" schedule for missed doses. A child never has to start over.
Q. I'd rather not vaccinate if there is any risk of side effects. Aren't these diseases so rare now that there's no danger in skipping vaccinations?
A. No. "Parents who opt against vaccination are putting their whole community at risk," says Dr. Margaret Fisher. Routine vaccination maintains the "herd immunity" that doctors spent the last century trying to achieve. A deadly disease can still be just a plane ride away.
Q. There seem to be more combination vaccines now. Are they just as safe?
A. Yes. The CDC urges doctors to use these new vaccines -- which undergo additional safety and immunity studies -- to reduce the number of shots and make it easier for kids to get all their vaccines on time. In addition to the new MMRV, there's also a shot containing DTaP, hepatitis B, and polio.