There is near unanimity among economists I know that a war-level investment is needed on policies designed to directly counteract the spread of the virus. Any investment that will marginally reduce R_0 may have a return in the hundreds of billions or trillions of dollars.
Let's try to get an order of magnitude sense of the returns that a policy like universal mask-wearing might have (and if such policies are not adopted immediately, the benefits of quickly evaluating their effectiveness).
Table 2 bfi.uchicago.edu/wp-content/upl… estimates total mortality risk of $60,000 per person in the US (adjusting appropriately for age in the VSL calculation).
This model imperial.ac.uk/media/imperial… suggests that every reduction in R_0 by 0.2 reduces total deaths by roughly 10%.
If our best estimate is 2.4, this means that a 10% reduction in transmission probability is worth about $6,000 per capita!
Next, how effective are masks? The evidence seems mixed: their most likely effect is in preventing transmission of the virus, and that is difficult to measure in RCTs. Countries where people wear masks appear to have much slower viral spread: .
However, this could be due to other differences in the policy-responses in those countries such as earlier social distancing measures and more widespread testing.
My read of the evidence is, masks likely provide little *protection* for healthy individuals outside high-risk environments (slatestarcodex.com/2020/03/23/fac…).
However, simple surgical masks likely impede transmission. Existing trials were not powered to investigate transmission, and the mechanism is clear but no well-identified studies. So what should we do?
1) Federal or state governments should immediately purchase a dozen cloth masks for everyone and strongly encourage everyone to wear masks when in public (perhaps even fine them if they don't).
Cloth masks probably cost less than a dollar to manufacture (<$12 for a dozen). If they reduce transmission by 10%, they return $6,000 in benefit.
I don't think any rational person could look at the evidence and say, there is less than a 1% chance that they reduce transmission probabilities by 10%. This is a crisis, and urgent action is needed.
2) We should immediately ascertain the benefits of masks. Spend a few million dollars, pick 100 counties in the US, and send a dozen cloth masks to everyone in half of those counties. In a few weeks, we know whether a $3 billion investment generates a trillion dollars or more.
The numbers are staggering and highlight the blindingly clear point: the returns to reducing the spread of the virus immediately are larger than any public policy in our lifetime. Act now!
