The case for vaccines

Two weeks ago, a research article published in 1998 in the medical journal The Lancet that had linked the measles-mumps-rubella (MMR) vaccine with autism was finally retracted. The study, along with long-standing fears about the vaccine preservative thimerosal, had prompted millions of scared parents to forgo or delay MMR vaccinations for their children, usually given as two shots before the age of five.

While the retraction is a welcome development, the study has caused significant and perhaps irreversible damage to public health. With a lower vaccination rate, there have been more frequent mumps and measles outbreaks in Europe and the United States. There is now a sufficiently large unvaccinated population in Great Britain to enable the continuous spread of measles.

But through all of this, autism rates have not declined. How did one research study lead to such severe distrust of the MMR vaccine and contribute to a general stigma of vaccines?

Most vaccines are composed of three components: inactivated or weakened viruses, preservatives to prevent bacterial and fungal contamination, and sometimes an adjuvant, which improves the potency of the vaccine. Because vaccines are made in bulk and shipped all around the world, contaminated vaccines can infect many people. Unfortunately, preservatives have gotten a bad rap since the late 1980s. While no link was ever found between the preservative thimerosal, a mercury derivative, and autism, the public became increasingly wary of thimerosal as autism rates continued to increase in the 1990s. Although the FDA removed thimerosal from most childhood vaccines in 1999, autism rates have continued to increase.

Understandably, families of autistic patients and autism advocates are frustrated that there remains a lack of understanding about autism, a developmental disorder with no cure that affects a person’s ability to communicate and socialize. But anti-vaccine advocates have taken advantage of this knowledge vacuum to draw a causal link between the MMR vaccine and autism because the first vaccine shot is usually given at the same age that the disorder is diagnosed.

In the 1998 study, the authors found that a group of 12 children diagnosed with behavioral problems consistent with autism had intestinal abnormalities. The scientists inferred — although they admitted they did not prove — that MMR vaccinations had caused the intestinal problems and subsequent autism diagnoses in most of these children. Anti-vaccine advocates supported the research findings despite the scientific and ethical concerns in the study that soon became apparent.

Scientifically, the study was dubious because it relied on a small, gender-biased sample — all except one child were boys. Rather than sample a broad population of autistic children, researchers specifically sought out children whose parents had noticed behavioral problems after MMR vaccinations. Ethically, the primary author, Andrew Wakefield, had at least two significant financial conflicts of interest: He had developed his own measles vaccine before the study was conducted, and he was being paid by lawyers for parents who believed there was a link between autism and vaccination. Most importantly, nobody has been able to reproduce the study’s results.

The very fact that The Lancet published this research without noticing these problems is still worrying to many scientists. But now that the article has finally been retracted, it is time for scientists and public health officials to be more vocal about the importance of the MMR vaccine and, indeed, all vaccines. Vaccines are one of public health’s greatest success stories; average lifespan has increased and quality of life has improved as a result of vaccines. Because of vaccines, most of us are unfamiliar with the horrors of diseases such as mumps and measles. Measles, for example, can lead to severe brain damage and even death. Finally, getting vaccinated is important for the greater good. Because of herd immunity, the more people that are vaccinated, the less likely it is that diseases will spread to unvaccinated individuals. While no vaccine has a 100 percent “take rate” — not everyone who is vaccinated will be guaranteed sufficient immunity to prevent infection — the benefits of getting vaccinated outweigh the costs.