Executive Summary

There is a crisis of scientific literacy today. Scientific journals are full of bad studies; online forums full of bad analyses of those studies. We try to dredge a path through the muck.

We do not see any conclusive data regarding the usefulness of Ivermectin as a treatment for COVID; however it is certainly not a cure. As a treatment, based on the extant data, we estimate it is likely to reduce severe outcomes by 20-40%. It is certainly not as effective as a vaccine.

Epistemic Status: Document completed in June 2021, with some inline updates in July 2021. The results of the TOGETHER study and confirmation of our doubts about several studies (including Carvallo) have led us to view Ivermectin in mid-August 2021 as most likely 10%-30% effective.


In January 2020, a new disease, COVID-19, caused a rapid outbreak in Wuhan. In March, outbreaks occurred worldwide. Lockdowns and other restrictions began. The disease was substantially more contagious than influenza, and had about a 1% death rate, with higher rates among the elderly (but not among the very young). The disease is closely related to SARS; there was no obvious treatment to reduce the death rate.

Origins Controversy

In Spring 2021, there was a paradigm shift in the Western media regarding the origins of the COVID-19 virus. Initial reports suggested it originated from zoonotic transfer at the Huanan Wet Market in Wuhan.

However, over the next year, research suggested this may not be the case. No intermediate animal population was found between bats (the reservoir for most coronaviruses; a sample with around 30 years of evolutionary distance was found in collected bat samples) and humans. Pangolins, in particular, were suggested but not supported by evidence. Furthermore, epidemiological research suggested that the first human cases in Wuhan were not people associated with the Huanan Wet Market.

The most likely alternative hypothesis is that it arose from a lab sample at the Wuhan Institute of Virology (WIV). This suggestion is obviously politically charged. Furthermore, it leads to multiple conspiracy theories regarding COVID-19 being released as a deliberate bioweapon.

Throughout Spring 2021 there were a variety of prominent articles on the topic. (Bulletin of the Atomic Scientists, Science Magazine, The Guardian, etc.) While there may never be conclusive evidence, many respected thinkers feel the lab leak theory (often derided as a “conspiracy theory”) is at least as plausible as zoonotic transfer.

Treatment Controversy

Now there is a controversy, at least in some parts of Twitter, regarding treatments for COVID-19. This is not entirely new; there was prominent controversy regarding hydroxychloroquine in 2020.

The Burden of Proof

There are two, completely separate, schemes of proof for medical treatments.

  1. The first is the "Western scientific consensus". Ideally, there are three elements demonstrably proved before the drug is used.
    1. The drug has a clear [mechanism of action].
    2. The drug's efficacy has been demonstrated in a peer-reviewed, double-blind, scientific study.
    3. The drug has been shown to be safe through [longitudinal study].
  2. The second is, roughly, the "There are no atheists in foxholes" approach.
    1. Simply put, in an emergency situation, we do whatever appears to work.

As a new disease causing widespread deaths and even more widespread disruption, the correct burden of proof here is obviously the second one.

But it must actually work. We cannot engage in cargo cult science to engineer the appearance that a treatment works, while it actually has no impact.