The two Marks created many Euros of value.

Over at Slate Star Codex, psychiatrist Scott Alexander has an ongoing set of debates. It’s called the Adversarial Collaboration Contests. The idea is to have each person start by taking a side that he/she believes in (adversarial) but also have them work together to try to reach a conclusion (collaboration.) In his ground rules, Scott explains:

Remember, an adversarial collaboration is where two people with opposite views on a controversial issue work together to present a unified summary of the evidence and its implications. In theory it’s a good way to make sure you hear the strongest arguments and counterarguments for both sides – like hearing a debate between experts, except all the debate and rhetoric and disagreement have already been done by the time you start reading, so you’re just left with the end result.

The third one in the series was posted yesterday and I found it quite impressive. (I haven’t read the first one because I was not that interested and I haven’t got around to the second one.)

Why am I impressed? For three main reasons:

  1. I like civil discussion where each side is actually trying to get to the truth. That minimizes the amount of game-playing, the number of gotchas, and the various other distractions
  2. In trying to get to the truth, each side seemed to learn from the other.
  3. I learned a lot about the facts of vaccination from the discussion.

As is my wont, I did find one omission somewhat troubling.

First, some highlights of the positives before I get to the omission.

The main goal of Mark Davis, a naturopathic doctor, “was to argue that there is enough reasonable doubt that routine childhood vaccines could contribute to hyper-inflammatory disease, and enough reduced harm from vaccine-preventable diseases from other medical and public health interventions (in countries with greater economic resources) that parents should be given wide latitude to make individual choices re: routine childhood vaccines despite the clear benefits to individual and public health from preventing those diseases.” And the outcome? “He became more convinced in his conversations with Mark Webb that widespread childhood vaccination is in the best interest of public health.”

The main goal of Mark Webb, a clinical researcher with a PhD in immunology, “was to argue that atopy and autoimmunity are likely not driven by vaccination, and that this idea is a distraction from finding the real causes of the increase in these diseases.” The outcome? “He became persuaded that policy should not just reflect the best evidence currently available, but should also reflect a certain degree of humility that there will always be something we don’t know.”

So based on that, I would say that Mark Davis moved closer to Mark Webb’s position.

Some of the things I learned (and I bet they learned) along the way are:

The differences between the United States and some other developed countries:

the argument, “vaccination should be mandatory” must contend with one uncomfortable fact: in many European nations vaccination isn’t mandatory, and those nations often achieve higher vaccination rates than in the US.

How tiny the known risks are:

For vaccination, the most common, well-documented, known risk is the potential for an allergic response to some component of the vaccine. The most common allergic component is egg, and people with severe egg allergies are instructed to consult their physician prior to vaccination. How common are allergies to vaccines? A good estimate is about 3 per one million doses. This would be the equivalent of about 200 people in France, or 35 in the US state of Ohio. This is the biggest recognized, known risk of vaccines.

The hygiene hypothesis (which they probably knew but was new to me):

the hygiene hypothesis is the idea that some of the bacterial and parasitic infections that modern medical technology has eliminated might have been performing an important function in the human immune system – and when you take them away you start seeing problems.

And some evidence for the hygiene hypothesis:

This hypothesis isn’t just high-level theoretical hand-waving. Parasites, such as hookworm, have been shown to induce the same kind of immune mediators that are commonly seen in autoimmune diseases. In fact, some people with diverse autoimmune, allergic and autoinflammatory conditions have started intentionally infecting themselves with hookworm. Based in part on this movement, clinical trials have been conducted, and more are currently under way investigating whether re-introducing parasitic infections such as hookworm can be used to treat Crohn’s and other autoimmune diseases.

The Amish and Hutterites:

A group of researchers identified a different German religious sect, called the Hutterites, which also engages in regular farming. They are closely related to the Amish, and came from similar parts Germany at similar times. However the norms of the Hutterites dictate a much lower interaction between livestock and children/pregnant women (most hygiene hypothesis evidence suggests prenatal, neonatal, up through young childhood exposure is the critical exposure period). This genetically similar group, who had less early-life exposure to the farm environment than the Amish, gets asthma at a rate 5-7 times higher than Amish farmers (Amish asthma rate is 2-3%, Hutterite asthma rate is 15%). The researchers then took dust from the Amish barns and forced mice to breathe it in. They found the dust protected the mice from developing an experimentally-induced allergic response, and that it caused real, measurable changes in the immune systems of these mice, consistent with what we see in humans who are less allergic, and consistent with the differences they saw in the Amish farmers who had low allergic disease compared to the Hutterites.

Their bottom-line policy conclusion:

We believe this coordination problem may be largely resolved without restricting individual freedom. Individuals who wish to invoke the precautionary principle for themselves and their families should not be penalized for doing so.

As is often true, many of the comments on the post are valuable also.

The one omission: discussion of the possible link between vaccination and autism. Here’s all they write about it:

Much ink has been spilled about vaccines and autism, and it is not our intent to cover that ground again here. Both authors agreed that the evidence does not support a link between vaccines and autism.

I would have liked to see why they think the evidence doesn’t support a link. I’m totally willing to believe that it doesn’t, and, indeed, my prior is that it doesn’t. The evidence convinced both of them. Why? What was the strongest evidence that convinced them? This inquiring mind wants to know.