Hysteresis: The Phenomenon Behind the Anti-vax Movement Despite overwhelming scientific evidence that vaccines are safe and effective in preventing childhood diseases, a significant minority remains skeptical, such as the anti-vax movement. Mathematicians show this may be due to "hysteresis", where an effect persists despite changed initial conditions. Interesting hypothesis. Not sure if I buy it on a social level, but the final paragraph boils the social phenomenon down to its essence, and this I do not doubt. The anti-vax movement isn't rooted in scientific understanding or belief. It is rooted in a philosophical distrust of government and the scientific community who these groups of people distrust believing them a serious threat to the philosophical core of their value systems. While that may or may not be a real threat it has no bearing on the truth of vaccines and autism, and the entirely unsubstantiated link between them. This has been reinforced by every study into the matter, epidemiological or otherwise, across the developed world, since the shocking discovery that (the since disgraced and delicensed) Dr. Andrew Wakefield fabricated his data in the Lancent-published studies that launched the contemporary anti-vax movement some 15 years ago. https://en.wikipedia.org/wiki/Andrew_Wakefield https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136032/ Not only that, but a recent May 2018 study also found on a mass scale that children with autism (and their siblings) are less likely to be vaccinated than healthy children: Vaccination Patterns in Children After Autism Spectrum Disorder Diagnosis and in Their Younger Siblings So, in point of fact, while the scientific and medical communities in 2018 are confident in asserting that vaccines DO NOT cause autism, which is usually the sort of claim these groups of people are very hesitant to make since it requires so much data to establish a negative with certainty, but in addition to this, they can now draw a correlation between anti-vaxxers and a significantly higher incidence of autism; although of course they haven't established or are even proposing causation at this point. *Special Note* There is a wonderful movement underway to remove paywalls obstructing access to full research data like the above study that is often government subsidized or grant funded, but are restricted with subscriptions costing money that often is NOT devoted to the authors of the studies in question, but the journals publishing them instead. Information like this, while more abstruse, has always been intended to be open source, and for the good of humanity. In the meantime, know that if are intensely interested in a study like the above, all you have to do to access it for free is email the authors of the study directly (they typically have university email accounts listed at the abstract page) and ask for it directly. They are permitted to distribute any articles they author freely to anyone who requests it.