Measuring Risk: Vaccines Save Lives, But Also Cause Health Problems

Once upon a time, smallpox was a demon, killing more human beings than all the wars in history. The virus could not be cured by antibiotics—those only work on bacteria. The only effective attack was prevention. Through a series of vaccines, by 1977 smallpox was effectively eradicated from the planet.

Credit: Lisa Blackshear

Viruses cause annoyances like the common cold, but they can also kill: Diphtheria, for instance, kills one tenth of those who contract it. Tetanus kills one third. Vaccines have greatly improved the odds of human survival, but there are risks. The tetanus vaccine is known to cause severe nervous reactions in one person out of 100,000, and severe allergic reactions in one person out of each million.

There is no question that vaccines have saved lives, and that benefits generally have outweighed risks. But with the scourge of many diseases passing out of living memory, a finer evaluation of risks is coming to the fore. What if the risks aren’t simple, immediate reactions to the vaccine, like getting a light case of the illness it’s intended to prevent? What if the risks involve subtler damage to the immune or nervous system?

Like the pesticide debate, the question with vaccines isn’t simply about whether or not they work and the safety of their primary components. The question is also about ingredients, which may cause unanticipated problems.

Vaccines have been controversial since their inception, for reasons ranging from interfering with God’s judgment against evil doers to modern concerns about individual risks. Horrific personal stories, hyperbole and some reputable studies purportedly linking childhood vaccines to everything from ear infections and asthma to autoimmune disorders and autism flood the Internet. Some sites offer credible information, while others simply offer quotes from people who are not identified beyond their names, and whose credibility therefore cannot be judged.

The Thimerosal Question

Aluminum, used to stimulate immune response, and antibiotics (to kill bacteria) are present in very small doses in vaccines, and a groundswell of concern about them may develop. But the chief villain in the eye of the anti-vaccine Internet storm is thimerosal, a mercury-based preservative added to many vaccines. In 1999 the U.S. Food and Drug Administration found that the regular schedule of recommended childhood immunizations put more total mercury—by way of thimerosal—into infants” bodies than recommended under more stringent guidelines set by the Environmental Protection Agency (EPA). That summer, the American Academy of Pediatrics officially recommended that the country move to thimerosal-free children’s vaccines.

Hundreds of parents say they watched their otherwise healthy children suddenly become autistic after getting routine vaccinations. Several lawsuits are in the works, aimed at court recognition of a link. “A lot of the vaccine critics feel that there are similarities between brain damage seen with mercury and the kinds of symptoms you see with autism,” says Dr. Robert Wolfe, professor of medicine at Northwestern University.

Representative Dan Burton (R-IN) is one of those convinced of a connection, and he believes that vaccines caused his grandson’s autism. “I”m so ticked off about my grandson, and to think that the public-health people have been circling the wagons to cover up the facts!”” Burton said in a Congressional hearing recently. “”Why, it just makes me want to vomit!””

But others argue that a move to ban thimerosal from childhood vaccines was premature. The health guidelines for mercury are based on the known effects of one of its organic forms, methylmercury. But thimerosal contains a different form of mercury, ethyl mercury. Does that let it off the hook? Not necessarily. The real truth is that ethyl mercury’s effects haven’t been studied widely.

The families whose wrenching tales of vaccinating their children only to find them suddenly autistic have avidly followed a small handful of studies supporting a correlation between thimerosal and autism. Among the best known are those by Dr. Andrew Wakefield, who linked autism to the mumps-measles-rubella (MMR) vaccine. In 1998, Wakefield and his colleagues published their findings in the unimpeachable journal Lancet. Their small study considered 12 children with delays in neural development, eight of whom had autism. All of the children had gastrointestinal complaints and developed autism within a month of taking their vaccine.

But Wolfe notes that no one has been able to replicate that study, the standard scientific method for establishing a causal link between an agent and a reaction. He says that there should have been a sharp drop in autism rates once thimerosal was removed from childhood vaccines, but to date there is no evidence of this.

He also points to a new study published in the Journal of the American Medical Association that seems to completely undercut Wakefield’s finding. The study looked at 537,303 Danish children born between the beginning of 1991 and the end of 1998. Eighteen percent of these children did not receive an MMR shot. The authors found no statistical difference in autism rates between the two groups.

Another study, also in Lancet, reported this year that children given vaccines containing thimerosal had blood mercury levels that were within safe limits. Sally Bernard, director of the parents” group Safe Minds, which is suing the vaccine industry, decried the study as “off base.” These days, none of the standard childhood vaccines in the U.S. contain thimerosal.

General Risks

Part of Krista Reitberg’s job as an immunization epidemiologist with Public Health Seattle and King County, Washington is to talk with families about childhood vaccines. While she will not tell parents that any of the recommended vaccines are less important than others, for those who waver, she recommends prioritizing vaccines that ward off the diseases that are most harmful to babies. (Vaccines have been linked to sudden infant death syndrome, though an Institute of Medicine study, announced last March, found no link between them.)

If you or someone in your family do experience an adverse effect, call the federal Vaccine Adverse Event Report System (VAERS) at (800) 822-7967.

“Certainly if you’re talking to a parent whose child has had an adverse reaction to a vaccine, that’s their one child,” says Reitberg. “But a parent whose child stopped breathing because he got whooping cough from an unimmunized three-year old is also that one child.”