Tuesday, May 7, 2019

Vaccines and Autism

I've been looking up vaccine rates and autism rates around the world since that topic just can't seem to leave my news feed. I enjoy doing research on issues like this if for no other reason than I am interested in the truth.

The stats can be tricky for several reasons.
  • There are a LOT of things for which people can be vaccinated, and the focus can vary around the world depending on what diseases are prevalent. Most charts focus on either DTP3 or something specific. I have not found a chart that captures everything going on in a particular place. 
  • I can't tell if the full spectrum of autism diagnosis is the same everywhere. In other words, some places could show more cases of autism or an accelerating/decreasing prevalence based on how they establish the range of the spectrum and how many personnel are available to diagnose. It's clear that in the United States, that method and ability to diagnosis are huge factors. The variance of ASD rates between states is crazy simply because of the difference in resources to diagnose and treat. 
  • It's absolutely true that autism have been rising significantly. However, keep in mind that autism wasn't even in the DSM until the early 80s, so there was not autism data before that. Since then, as the definition/understanding has expanded, obviously the diagnosis has grown. In addition, many people who have once been diagnosed with mental illnesses are now considered to be on the spectrum. (See "The Real Reason Autism Rates Are Up In The United States" for more information.) A number of years ago, a study was released showing that certain states in the US had much higher rates of child abuse. That wasn't actually true. Abuse rates are pretty consistent -  if we define abuse the same way in every state.  Poverty can appear to rise and fall in the US not because people's financial situations change, but because we change how we define poverty. In the same way, autism is rising - but that's obviously going to happen as we continue to broaden the diagnosis and focus on diagnosing.
I've always done research on this topic by reading the competing studies, but that usually just leads to my reading a lot of sound and fury. (I don't believe there is a connection, btw - see articles like this from the Annals of Internal Medicine, or "Safety of Vaccines Used for Routine Immunization of US Children: A Systematic Review" from the American Association of Pediatrics, this podcast from Science VS. (which also talks about some of the other possible side effects), or the tons of resources from the Immunization Action Coalition.)

So, I thought I would take a different approach this time and look for what is happening around the world. In spite of the caveats I mentioned earlier, there are trends we can observe. I will be using data from OurWorldInData.org. They compile data from other organizations and make it understandable; they also allow downloads of their charts for use in presentations :)



It's worth reminding ourselves that, though TB remains a problem, there has been a fantastic drop in fatalities. Vaccines have clearly been a blessing to the world in terms of saving lives. Now, let's isolate measles, since measles is experiencing a recent resurgence. According to the WHO, it has quadrupled globally in 2019. 

Note that as measles vaccinations increased, the cases dropped dramatically. By way of contrast, Africa, one of the least vaccinated continents, has seen a 700% surge in measles this year.

The goal, by the way, is something called "herd immunity."100% coverage is not needed. Once a certain threshold has been crossed (and that can vary by disease), the disease functionally dies out. Vaccines work at their peak effectiveness in conjunction with herd immunity. So, yeah, vaccines work pretty well when they are administered into the "herd" environment in which they are most effective. It's not that they can't work for outlying individuals, but there needs to be community buy-in to really see them do their magic. Check out this video, "How Does Herd Immunity Work," from the Oxford Vaccine Group.



Around the world, the success of vaccines has been remarkable. We, of course, benefit from this. Note how vaccines have changed the health and mortality landscape in the U.S. alone.  




But what about the fear of autism? Let's just look at data as it plays out the real world. Here is a map showing DTP3 vaccinations:



Here is the share of children vaccinated against measles.


Now, here is the share of children diagnosed with autism spectrum disorders in 2017 (the last year for which I could find comprehensive data).



One would be hard pressed to establish a vaccine/autism correlation based on this data. ASD rates don't correlate with vaccines, at least not by using our current metrics. Considering that the broadening of definitions and better diagnosis has made the ASD numbers misleadingly inflationary, the lack of correlation is even more striking. A few other things to note:


Google "causes of autism." Find well-respected organizations that are trying to figure this out, like Autism Speaks, or the National Center For Health Research, or the Mayo Clinic, or the Autism Society, or the American Speech-Language-Hearing Association, or the American Pregnancy Association, or the National Autistic Society, or the Association For Science In Autism Treatment, or the Emory University School Of Medicine, or the University of Queensland's Brain Center, or the Southwest Autism Center of Excellence, or the Children's Hospital of Philadelphia, or a host of others.

Perhaps they will be helpful in shedding the light of truth on this complex issue.

1 comment:

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