Anti-vaccinationists have made a wide range of claims about the dangers of vaccines. In spite of the fact that they have generally had neither data nor a plausible mechanism for the claimed effect, several of their claims have been investigated by researchers.
As it turns out, the anti-vaccinationists are remarkably consistent. Time and time again, they are shown to be wrong. I’m not sure how many times a group needs to be wrong before people stop seeing them as credible. Perhaps people need to be reminded of how many times this group has been wrong?
Vaccines and autism
Gerber and Offit published a paper titled “Vaccines and autism: a tale of shifting hypotheses” in 2009, which neatly summarised some of the various claims being made by anti-vaccinationists.
For MMR, the authors discuss a number of different studies undertaken by researchers in different countries (in spite of the fact that “no data supporting an association between MMR vaccine and autism existed and a plausible biological mechanism was lacking”). Although none of these studies alone provides perfect, definitive proof that MMR does not cause autism, when you look at them together you can see that the evidence consistently points to the anti-vaccine movement as being wrong.
On thimerosal, the authors write that “Despite the biological implausibility of the contention that thimerosal in vaccines caused autism, 7 studies—again descriptive or observational—were performed”. Again, studies consistently failed to find the claimed association.
In the first two cases, we can see that there are some noteworthy similarities – a lack of either data or a plausible mechanism for the claims of the anti-vaccine movement, research nonetheless being undertaken, and studies finding no evidence to support the claims.
In the third case, where anti-vaccinationists had claimed the problem was too many vaccines, we once again see a lack of biological plausibility. This time, the authors referred to data showing: that vaccines do not overwhelm the immune system; that multiple vaccinations do not weaken the immune system; and that autism is not an immune-mediated disease.
Regarding the three hypotheses, Gerber and Offit concluded that:
These studies [into MMR and thimerosal], in concert with the biological implausibility that vaccines overwhelm a child’s immune system, have effectively dismissed the notion that vaccines cause autism. Further studies on the cause or causes of autism should focus on more-promising leads.
Fast-forward to 2013 and we see new research… into ‘too many vaccines’. Guess what? Increasing Exposure to Antibody-Stimulating Proteins and Polysaccharides in Vaccines Is Not Associated with Risk of Autism. Once again, in spite of the anti-vaccine movement having neither data nor a plausible mechanism, research has been conducted into their claim. Once again, the evidence does not support their claim.
I’m far from the only person to have noticed that the anti-vaccine movement is consistently wrong. Among others, Rümke and Visser got there before me. I should point out that I have not read the full text of their paper, but I have looked into some of the claims referred to by the authors (regarding autism, SIDS and multiple sclerosis). Here’s what they say about anti-vaccine scares:
During recent years a scala of diseases or symptoms have been associated with vaccination (presumed side effects). Careful and extensive investigations have shown that such hypotheses could not be supported. Examples are allergic diseases as asthma, diabetes mellitus, multiple sclerosis (after hepatitis B vaccination), autism and inflammatory bowel disease (after MMR vaccination) and sudden infant death syndrome.
As I say, I’m not sure how many times a group needs to be wrong before people stop seeing them as credible. But then, we don’t seem to be very good at learning from vaccine scares.
Early 1970s: a lone maverick claims a vaccine is causing harm to children. The media pick up on the story and run with it. Within a few years vaccine coverage drops from 77-81% (1966 to 1972) to a low of 31% by 1976 – and does not get back above 50% until 1980. It turns out that the case series that the maverick (and the media) caused a panic over included children who had symptoms before they had been vaccinated. Also, ridiculously, it apparently included children who hadn’t even had the pertussis vaccine that the scare was about.
Late 1990s: a lone maverick claims a vaccine is causing harm to children. The media pick up on the story and run with it. Vaccine coverage drops (over six years) from 91% to 80%. It turns out that the case series that the maverick (and the media) caused a panic over included children who had symptoms before they had been vaccinated.
There’s probably a lesson in there somewhere. Don’t get too excited about case series? Be wary of lone mavericks making claims about the dangers of vaccines? Don’t take anything newspapers publish on health too seriously? Actually, there are probably several lessons in there.
Once again, I’m sure I’m not the only person, or the first, to have noticed the similarities. Brian Deer has written about both cases (John Wilson and Andrew Wakefield being the lone mavericks in question).
The anti-vaccine movement has been wrong, wrong and wrong again (actually, that’s probably not enough “wrongs” – I’m not sure quite how many there should be). I expect that, unless the movement takes the unlikely step of ceasing to offer implausible hypotheses about the dangers of vaccines, they will be wrong again. Watch this space.