Adding to parental fears are last year's withdrawal of the new rota-virus vaccine because of an association with an intestinal blockage called intussusception, and publicity surrounding the use of thimerosal, a vaccine preservative that contains mercury. States require vaccinations for children in public schools unless there are medical reasons a child should not be immunized, such as a severe allergy to something in the vaccine or a compromised immune system. All states except Mississippi and West Virginia grant exemptions based on religious beliefs, and 17 states consider philosophical objections. Now what we mean by safe is something has to be absolutely free of negative consequences. That's unrealistic, he says.
Nothing is absolutely safe.
People die from choking on food or taking baths. So does chocolate. So do peanuts. That's one reason why studies are needed to determine which children are most vulnerable to a bad reaction to vaccines, says Barbara Loe Fisher of the National Vaccine Information Center in Vienna, Va., an advocacy group for those who question vaccine safety. If they have a problem, it's very difficult to know which vaccine caused it.