This doctor is asking that we do a vaccinated vs. unvaccinated study to determine if vaccines cause more or less “outcomes” (read: autism) than what is attributed to them. I never went to medical school, but I did go to epidemiology school with a lot of medical students. Maybe this doctor was too busy with other things when he was introduced to epidemiology, because it is very clear that he has no clue what he is asking for. (Or maybe he is just selectively remembering what is good for him and what isn’t?) See, in the world of epidemiology, there is a hierarchy of epidemiological studies. In ascending order of ability to show causality, the studies are these:
- Case Study (describing one person with the condition, a case)
- Case Series (series of cases)
- Ecological Study (analysis of group statistics..for example, comparing rates of disease between two countries)
- Cross-Sectional Study (assessing individuals at one time, such as a survey)
- Case-Control Study (studying those with the condition vs. those without)
- Cohort Study (following subjects over time to study the initiation and progression of a condition)
We did the case studies. We looked at children with autism and determined that there was no biologically plausible way for vaccines to cause autism. Furthermore, instances of unvaccinated children with autism kept coming up. There were even case studies of autism before many vaccines were around. So we moved one step up.
We did the case series. We looked at groups of children with autism and determined that some were vaccinated while others weren’t. Even within those who were vaccinated, we noticed that their symptoms preceded vaccination. In those who were unvaccinated, we noticed that their symptoms were similar to children with autism. And, like with the case studies, we found that vaccines have no biologically plausible way of causing autism. So we moved one step up.
We did an ecological study. We looked at autism rates in other countries and in this country. After adjusting for differences between factors in the different countries, we found that there is no difference between countries in the rates of autism. Furthermore, there are differences between those countries when it comes to vaccine availability. That is, it didn’t matter if the countries vaccinated more or less, we found no difference in autism rates. So we moved one step up.
We did surveys. (Heck, even the anti-vaxers wanted to do surveys.) And, after adjusting for all sorts of biases that surveys present, we found no difference between vaccinated and unvaccinated groups. (The anti-vaxers found a similar result, but that doesn’t stop them from wanting another round at it.) So we moved one step up.
We did case-control studies. We took children who had autism and children who had no autism, then we looked at their immunization records. It turned out that both groups had equal odds of being vaccinated. There was no difference between the two groups.
In short, everything we’ve done to date has failed to find a link between immunizations and autism. So you would think that the vaccine-autism link would be dead. Well, it isn’t. That doctor I told you about in the opening sentence wants a cohort study (aka Randomized Clinical Trial or Randomized Controlled Trial). Never mind the millions of dollars and thousands of man-hours lost doing such a study when all the previous evidence has shown no link. Never mind that we could do much better things with those resources. No. The anti-vaccine groups want to slay their dragon. They want to prove that vaccines did to them what they think vaccines did to them.
So what would it take to do such a study? Well, it would go like this:
Recruit participants at birth. Parents would be approached and told that their child would be participating in this study. Without their knowledge, their child would be assigned to one of two groups. One group is vaccinated while the other is given placebos. If you really want to give this study strength, you keep the group assignments secret from even the researchers.
Follow participants until a certain endpoint. This endpoint can be anything you want it to be: the diagnosis of autism, the age of ten — after which a diagnosis of autism is very rare, death, anything. Once all your participants reached the endpoint, then the study is done.
Analyze the data. You would then “unmask” the participants’ assignments and compare the vaccinated to the unvaccinated groups to see which of them reached those endpoints faster or in greater proportion. Which group has the most autistics?
However, can you see why this study is unethical and very likely to fail? First off, one half of the children — those assigned to the unvaccinated group — would be deliberately unprotected against some very nasty diseases. You tell me if you want your child to be unprotected against measles. If you’re an anti-vax parent, you probably don’t care. You probably think that your child will survive anything and come out stronger, despite all the evidence to the contrary. But what if you’re a pro-vaccine parent? Would you like your child to maybe not be vaccinated? And, if you’re anti-vaccine, would you like for your child to maybe be vaccinated?
Then there is the issue of bias. If you’re an anti-vaccine parent, and you think your child was vaccinated, you might make a bigger deal out of every little developmental delay. If your child doesn’t walk at 12 months, taking a few more weeks to get going, you might be more inclined to blame the vaccines. Or you might give your child an unproven therapy to try and “detox” them, and it might be that therapy that makes them ill.
On the other hand, if you’re a pro-vaccine parent, you might take your child to get a second round of vaccines if you think that your child ended up in the unvaccinated group. You want to make sure your child is protected, and, frankly, I can’t blame you for that. Also, being the responsible parent that you are, you might take your child to regular check-ups and discover autism (or any other “outcome”) much earlier than people who don’t take their children for check-ups.
And that’s just a few of the biases that could creep into this study.
The biggest problem with the study will be the deliberate lack of vaccination of half of the participants. No Institutional Review Board will allow you to do this because the liability is too great. If one kid in the control (unvaccinated) group get sick and dies from a vaccine-preventable disease, you will no longer be allowed to conduct research on human subjects, ever.
Of course, anti-vaccine activists will say that there are plenty of unvaccinated children, so finding children whose parents will deliberately leave them vulnerable to deadly pathogens wouldn’t be a problem. In that case, you’re not asking for a randomized clinical trial because you’re removing the “random” from it and you’re inserting a huge bias. If you see vaccines as an evil big enough to keep your children from being vaccinated, how likely are you to report that your child has autism, thus disproving your theory? In these cases, you’re asking for a case-control study, which has been done over and over again.
How much time, money, and God knows what other resources do you want us to keep on wasting in order to slay your dragon, to chase down your windmills, to find the bogeyman under your bed?
Then again, it’s not like ethics have kept the anti-vaccine forces from doing their thing.