Evidence Base for Wearing Face Masks to Control COVID-19 Is Growing

As we transition from lockdowns to the next stage of getting through this pandemic, face masks are becoming a symbol of what the new normal is to look like. Face masks have also become a symbol of a culture war, and I can understand why tensions are high. Political polarization was really high before the pandemic. Lockdowns only increased the social tension and unrest. There are reasons people do not want to wear masks, ranging from infringement on civil liberties or not wanting to appear weak to that it can be more than a tad uncomfortable. I get it. I personally would rather not wear one either. At the same time, I have to ask myself what the evidence on face masks says. I wrote a piece on the topic last month entitled A Libertarian Case for a Temporary, Partial Face Mask Mandate During the COVID-19 Pandemic. To summarize my argument for face masks:

1. N95 masks and surgical masks are much more effective than cloth face masks. 
2. The argument for face masks is stronger when being inside since germs dilute and decay in the outdoor air more quickly and effectively. 
3. Face masks do a better job of slowing transmission from someone than they do at preventing someone from catching COVID-19 from someone else.
4. There is a minimal cost of inconvenience, and there is even some evidence that face masks provide a net positive economic benefit. 
5. The public health concern of stopping the pandemic from getting worse overrides the discomfort or civil liberties since the decision to not wear a face mask could very well harm another, thereby violating the non-aggression axiom. 
6. As such, there should be a temporary, partial face mask mandate. It should be limited to indoor setting where people are likely to be close to one another. It should also be limited to when the rate of transmission is still high where it would likely cause another surge in infections.

What has changed in the past few weeks? There is more evidence that has come into play. When I first looked at this issue last month, the evidence was limited and often contradictory. Various public health experts were giving conflicting advice. Some were saying to not wear masks because it could make the problem worse. Others were saying that we should because it prevents transmission. It was hard to figure out what was going on. Now we have greater evidence as to what is going on. Here are some of the more recent findings. 

• A study in the Proceedings of the Royal Society A found that the median effective R0 of less than one (the amount required to eradicate a disease) could be reached even if face masks were only 50 percent effective (Stutt et al., 2020). This study also found that face masks are twice as effective as slowing the rate of transmission when they are worn before symptoms appear.
• Most previous study on the effectiveness of face masks was in the context of healthcare settings. A meta-analysis from The Lancet (Chu et al., 2020) covering 172 studies analyzing the effects of social distancing, face masks, and eye covers. The study found that there low-certainty evidence supporting the use of face masks. Social distancing measures had a medium-level certainty. 
• The Institute of Labor Economics analyzed the use of face masks in Germany to find a 40 percent reduction in the rate of transmission (Mitze et al., 2020).
• An Italian researcher found that face masks encourage social distancing (Marchiori, 2020). 
• The Centers for Disease Control and Prevention (CDC) analyzed the COVID-19 outbreak on the Navy's USS Theodore Roosevelt (Payne et al., 2020). They found that those who wore face masks have a lower infection rate than those who did not wear face masks (55.8% versus 80.8%). 
• The World Health Organization (WHO) changed its recommendation from not wearing face masks in public to wearing them in public.

I am sure we will see more and more evidence coming in about various measures to mitigate the spread of COVID-19. Face masks are not meant to be 100 percent or bullet-proof because that is the nature of cloth face masks. What we are seeing, though, is more evidence that face masks can be effective in flattening the curve. Per The Lancet study, I find that social distancing is more effective than face masks (also see Hsiang et al., 2020). That is why face masks still need to be accompanied by social distancing, hand washing, and other non-pharmaceutical interventions.