I posted recently about the discussion between Phil Magness and Jeremy Horpedahl about mask mandates to deal with COVID-19. My sometimes co-author and former student Charley Hooper wrote the following on masks in a recent email. He’s given me permission to share it. The bottom line: the evidence in favor of masks, let alone mandates, just does not seem to be there.

Here’s Charley:

The only randomized controlled trials conducted to study the effects of wearing masks and washing hands show that those two preventative techniques don’t significantly reduce the spread of the influenza virus. In some studies they help a bit. In other studies, they hurt a bit.

“Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on transmission of laboratory-confirmed influenza.”

[Source: https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article]

Why did I mention influenza and not COVID? COVID-19 is supposed to be transmitted by the same mechanism as influenza and influenza has been around long enough to be better studied.

The Xiao study referenced above contains this shocking admission: “It is essential to note that the mechanisms of person-to-person transmission in the community have not been fully determined. These uncertainties over basic transmission modes and mechanisms hinder the optimization of control measures.” Scientist don’t have a handle on how the flu transmits throughout the community. If you don’t know that basic fact, it’s pretty hard to effectively prevent the transmission of influenza! By extension, I think it’s safe to say that scientists don’t understand how the SARS-CoV-2 virus is transmitted.

The influenza virus can last about five minutes on a human hand. (“Virus survived on hands for up to 5 min after transfer from the environmental surfaces.”) I suspect that the SARS-CoV-2 virus lasts about the same length of time on hands.

[Source: https://pubmed.ncbi.nlm.nih.gov/6282993/]

Therefore, if you don’t wash your hands but also don’t touch your eyes, nose, or mouth shortly after touching an infected surface. you should be fine.

There was one randomized controlled trial of the use of face masks to prevent COVID-19. The study was conducted in Denmark in April and May 2020. The results were not statistically significant but showed that the mask group suffered a 1.8% infection rate while the control group suffered a 2.1% rate (95% confidence intervals = 46% reduction to 23% increase due to masks). In other words, masks helped but were not a panacea.

[Source: https://www.acpjournals.org/doi/full/10.7326/M20-6817]

Other studies show the benefits of wearing masks, but they are correlational, population-based studies that identify relationships but don’t necessarily prove cause and effect. I’m not saying that masks don’t work. I’m instead highlighting some of the scientific uncertainty around the use of masks. With this uncertainty, COVID absolutism is unjustified and harmful.

The rule seems to be that the less people understand about something, the more adamant their beliefs.