Economist Writing Every Day

How well do masks work at preventing disease transmission? This is a question that many of us have been asking throughout the pandemic. I have been trying to read as much about mask effectiveness as I can (for example, here’s a Tweet of mine from way back in June 2020). I think the bottom line is that, if you want really good RCTs of mask use during the COVID pandemic, there is surprisingly little evidence in any direction. But there are lots of studies, less well done but still OK, suggesting that masks do provide some protection.

I don’t want to wade into all of that research here, because Bryan Caplan has been doing that lately himself. His reading of the literature is that masks aren’t a silver bullet, but he suspects “that masks reduce contagion by 10-15%.” Still he thinks that the costs of masks (inconvenience, discomfort, and dehumanization) are large enough that they don’t pass a cost-benefit test. But this seems like a very strange conclusion given that he suspects masks reduce contagion by 10-15%! So let’s be explicit about the cost-benefit analysis.

[I am assuming that reducing contagion by 10-15% means 10-15% fewer cases and deaths. I see this as a bare minimum, since contagious disease can follow exponential growth trends, so 10-15% less contagion could mean that cases/deaths are reduced by more than 10-15%, but I’m making a simplifying assumption and the hard case.]

Quantifying the costs of the pandemic deaths is tricky, and it’s something that Bryan and I have debated before. Perhaps this is just a rehash of that debate (Bryan is highly skeptical of the VSL estimates), but I think it’s worthwhile to plug in some numbers.

What numbers should we use?

Kip Viscusi’s SEA Presidential Address (which is an update of results published in an earlier journal article) tries to estimate the mortality and morbidity costs of COVID-19. He estimates that for 2020 alone, the mortality and morbidity effects of COVID cost the US $5.5-5.9 trillion. But that’s using an average VSL. Since we know that COVID-19 disproportionately (but not completely!) impacts the elderly, which should make an adjustment to discount that amount. Doing so, Viscusi estimates that the mortality and morbidity costs are $3.4-3.8 trillion for 2020.

But that’s only for 2020. And since about 47% of the cases and 43% of the deaths have come in 2021, and the pandemic is nowhere near over in the US, it seems like a reasonable assumption that at least 50% of the cases and deaths (and costs) will be in 2021. As a rough approximation, we can double the cost: $6.8-7.6 trillion.

If the mask wearing we have done so far in the US reduced contagion by 10-15%, without masks the costs would have been something like $7.5-9.0 trillion. In other words, wearing masks saved $0.8-1.3 trillion in mortality and morbidity costs. Let’s just call it roughly $1 trillion (these number are all very rough estimates).

Since there are about 330 million Americans, the social benefit from all the mask wearing we did in the past 18 months works out to about $3,000 per person. Do the social costs of inconvenience, discomfort, and dehumanization exceed these benefits? That’s very hard to measure in practice, but economists have a useful tool to simplify the process: willingness to pay.

So here’s the $1 trillion question: would Americans have on average been willing to pay $3,000 each to have not worn a mask in the past 18 months?

I suspect some would say yes. Bryan Caplan might! But many Americans wouldn’t pay that much. Lots of Americans, for example, voluntarily purchased masks even before there were widespread requirements to wear them. They have a negative willingness to pay!

Perhaps you think my calculation has some errors. Maybe Viscusi is overstating the costs by half. You can still use this framework: in that case, would that average American have paid $1,500 to not wear a mask? Still, I’m skeptical. But if we are going to use cost-benefit analysis and a willingness to pay standard, we should try to put some numbers on it and follow the numbers where the logic leads.

We can change other parameters too in this back-of-the-envelope calculation. Let’s assume masks reduce contagion by 25%, which is still not perfect, but is closer to what economists have estimated the impact of mask mandates would be. Now the social benefits from reduced mortality and morbidity are over $2 trillion, so Americans would need a WTP of over $6,000 for mask wearing to fail a cost-benefit test.

Ultimately my estimates here are just a simple estimate. But I believe I’ve taken account of the major costs and benefits, and tried to put reasonable numbers on them (which you can play with yourself). A final question: why not leave the choice up to individuals? Isn’t economics primarily a science of individual choice, rather than social choice?

To that second question, I would say: economics is both! We study both individual and social choice. And in the context of contagious diseases, we are most certainly the realm of trying to think about social choices. Social choice doesn’t always mean we need a coercive governmental response (though it might), but I believe the question Bryan and I are both trying to address is: Was it a good idea for people to wear masks?

Given the large social benefits (using Bryan’s own guess of mask effectiveness), it seems that most individuals who are trying to consider those social benefits and their private costs should have opted to wear masks. And most did. That’s great! Some of this, of course, was due to coercive government rules. But given the calculation I have presented here, the rules probably pass a cost-benefit test (even if we would prefer people to take the action voluntarily).