February 28, 1998. A century of vaccine science had saved countless lives. People were happily being vaccinated against a myriad of horrible diseases, nary a worry in their immunized minds.
Enter Dr. Andrew Wakefield who, on that fateful February day, published a paper in The Lancet suggesting that the measles-mumps-rubella (MMR) vaccine caused autism spectrum disorder in children.
The study itself turned out to be massively flawed, and was later retracted by The Lancet’s editors, but not before Dr. Wakefield had fired the opening salvo in yet another war on vaccines.
Opposition to vaccination is almost as old as vaccines themselves, beginning shortly after the introduction of the smallpox vaccine at the end of the 18th century. Vaccination was a novel concept, and the public concern centered on both how well it worked and the religious and philosophical objections to mandatory vaccination laws.
Nearly a century later, a concerted anti-vaccine campaign in Stockholm succeeded in reducing smallpox vaccination rates to around 40 per cent, compared to ninety per cent in the rest of Sweden. In doing so, the campaign unwittingly conducted a controlled trial of vaccine efficacy: Stockholm suffered one of Europe’s last major epidemics of smallpox in 1874. Unsurprisingly, vaccination rates promptly rose.
There is now little doubt that vaccines are effective. Prior to the rollout of the diphtheria vaccine in the 1920s, there were over 20,000 cases of the disease in the United States annually. In 2010, following less than a hundred years of vaccination, there were no cases. None.
Estimates show that routine vaccination saves 33,000 lives and prevents 14 million cases of disease in every birth cohort in the U.S. Smallpox has been eradicated worldwide. Endemic transmission of horrific and potentially lethal childhood illnesses like polio, mumps, and rubella has been eliminated in the developed world.
There is an argument to be made that vaccination is the greatest public health intervention in human history. Yet the anti-vaccine movement lives on, gaining strength like the mythical hydra, sprouting two heads for every one that evidence bloodily severs. If the benefits are so easily demonstrated, why all the backlash?
Poorly done studies like the Andrew Wakefield example certainly don’t help. But since scientific journals are often inaccessible outside the ivory tower of academia, this cannot be the only factor fueling the fire.
In North America, vaccination takes place almost entirely in children, making parental perception decisive in its success. Parents are under a constant barrage of health information. While the 1800s had tracts and journals, we now have newspapers, blogs, and social media.
Unfortunately, many of those involved in reporting the news have no training in examining the strengths and weaknesses behind a health claim. Pressure to increase readership fills pages with sensationalized, credulous reporting of the most eye-catching claims, with little discussion of the evidence behind them, or how the findings might apply to everyday life.
One week, eggs are a health panacea; the next, they cause cancer. One week, vaccination is beneficial; the next, it’s too risky to recommend. In this climate, it becomes impossible for parents to know what, or who, to trust. So parental trust shifts mainly to other parents, especially those with a high profile.
Celebrities have had a massive effect on the public perception of vaccination. Jenny McCarthy and Jim Carrey hold up her son as a child made ill by vaccination. Oprah often expresses concern about the safety of vaccines, or features parent guests who are outright anti-vaccine. Nevermind that they have the same amount of medical training as your mailman.
The parents who forgo vaccination are often among the most highly educated. How are they so easily swayed by anti-vaccine rhetoric? It’s interesting that many parents cannot articulate exactly why they are against vaccination, suggesting an emotional component to their objection.
Perhaps vaccines are a victim of their own success. Widespread, long-term vaccination programs mean that many parents have never lived in a world where children are regularly paralyzed by polio. They tend to underestimate the occurrence of these vaccine-preventable diseases and the risks associated with infection, but overestimate the incidence of severe complications.
At the same time, disease is seen as something that happens by chance, inflicted by a roll of the cosmic dice. A common theme in anti-vaccination literature is that vaccines are a choice made by parents and inflicted on children, an usurpation of child rights. Parents may feel directly at fault if complications do occur, and may be unwilling to take the risk.
Vaccine safety is an important issue. While stories of sudden-onset autism and other severe complications are terrifying to parents, there are straightforward ways to test if a given intervention is having an observed effect. Anecdote is not evidence.
When it comes to vaccine trials, there are some unique hurdles to overcome. Since no evidence-based argument can be made against the effectiveness of vaccines, they cannot be ethically withheld from patients. This rules out a gold-standard, double-blinded, placebo-controlled trial.
One option is to perform observational studies. Simply look at the incidence of a particular disorder like autism in unvaccinated children and compare it to the incidence in children who are vaccinated according to schedule. Far from being science-y and opaque, this is a sensible, straightforward approach.
Multiple studies of this kind have been done for every recommended vaccine. Not one has found a consistent causal link between autism — or any other commonly cited complication — and vaccination.
Faced with evidence, anti-vaccine conspirators simply move the goalposts. Now, it’s not just MMR that causes autism; it’s the mercury in vaccines. So you demonstrate that there is no link between mercury and autism. You even take all of the mercury out of vaccines. All better? Nope, now the problem is that we are giving children too many vaccines, too quickly. Like Alice and the elusive Red Queen, vaccine advocates must keep on running just to stay in the same place.
It is likely that there will always be an anti-vaccine movement, and that no amount of evidence will assuage every last doubt about vaccine safety or usefulness. But at what cost?
In 2008, ten years after Wakefield’s original article, measles was declared endemic in Britain for the first time in 14 years. It was the direct result of a decade of poor MMR coverage. Meanwhile, vaccine-preventable diseases are on the rise again in North America. The longer the trend towards forgoing vaccination continues, the longer children are put at unnecessary risk.
Science provides a set of tools with which we can reasonably test our beliefs. Celebrity “wisdom” or anecdotes play upon our fears and our natural tendency to evaluate the validity of statements based on the status of the speaker. We must instead look to the evidence.
