Jury Still Out on Link Between Vaccines and Autism
Published April 13, 2018 | Opinion
Epidemiology is a basic science, not an applied science. It is not designed to prove anything.
(CDC) clearly states it on its website.1 It is stated in nearly every newspaper or magazine article written, either by the author or by someone the author has quoted.
In a recent article in HealthDay, postdoctoral fellow Ousseny Zerbo of the Kaiser Permanente Vaccine Study Center was quoted as saying, “[W]e know through numerous scientific studies that there is no association between childhood vaccination and the incidence of autism spectrum disorders.”2 You can find some variation of this statement in countless other articles. “The scientific evidence is very clear: There’s no link between vaccines and autism.”3
Here’s another one: “The research is clear: Vaccines don’t cause autism. More than a dozen studies have tried to find a link. Each one has come up empty.”4
Here’s one of my favorites: “To be clear, there is no current scientific debate about whether vaccines cause autism. Study after high-quality study—carefully conducted and peer-reviewed—has provided overwhelming scientific evidence that there is no link between childhood immunizations and autism.”5
I could fill many rooms with articles, excerpts from websites and presentations declaring positively and without a doubt that there is no link between vaccines and autism. I could probably fill one room with such declarations from CNN’s chief medical correspondent Sanjay Gupta, MD. Here’s one of my favorites from Dr. Gupta: “Studies […] show no link between vaccines and autism. That is not a matter of opinion. It is a matter of fact.”6
It’s a fact?
No, it is not a fact, and it is irresponsible to say that it is. Why? Because all that research and all those studies and “scientific evidence” often cited to assure the public that there is no link between vaccines and autism are based largely on epidemiological studies.7 8 Epidemiology is a basic science, not an applied science. It is not designed to prove anything. What epidemiology is designed to do is “point the way for further research by fields of applied science that are more capable of solving problems and finding answers.”9
According Freedman Green, MD, “Epidemiology is concerned with the incidence of disease in populations and does not address the question of the cause of an individual’s disease. The question, sometimes referred to as specific causation, is beyond the domain of the science of epidemiology.”9 10 11
“Even the most rigorous epidemiological studies suffer from a fundamental limitation, states Georgia Ede, MD. “At best, they can show only association, not causation.”
Dr. Ede adds, “Epidemiological data can be used to suggest hypotheses but not prove them. … Epidemiological studies, at their best, can only point out a possible connection between two things, but that is only the very first step in trying to figure out whether or not there really is a connection between them.”9 10 12
Former director of the U.S. National Institutes of Health (NIH) Bernadine Healy, MD concurred with both Freedman and Ede when she said in a television interview, “Populations do not test causality, they test association.”13 14
Dr. Healy was referring to the numerous epidemiological studies that have been done to determine if there is a causal link between vaccines and autism. She was making the point that you cannot rely on epidemiological studies to test causality, because epidemiological studies only have the ability to show a correlation. And correlation is not the same as causation.
So, again, in response to Gupta’s statement of fact about there being no link between vaccines and autism, it is simply not true. Belief and fact are two different things. Gupta, the CDC and many other individuals and institutions may believe there is no link. However, many others believe there is or might be. On this question of a link between vaccines and autism, Healy perhaps said it best…
The more you delve into it, if you look at the basic science, if you look at the research that’s been done in animals. If you also look at some of these individual cases, and if you look at the evidence that there is no link, what I come away with is… the question has not been answered.13 14It sounds more like the jury is still out on this issue.
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