People often find it easier to focus on one issue at a time. I’m no different in this regard, which is why I try to force myself to think of problems from a “multivariate” perspective.

I would encourage people to be skeptical of reports that “solution X” won’t work. Tyler Cowen linked to a recent example today, which evaluates Paul Romer’s proposal for mass testing. It’s not that these studies are wrong; indeed I believe the skepticism is usually justified. Rather they must be understood in context.

In my view, there are at least three very useful policies for addressing Covid-19:

1. Test-trace-isolate
2. Wear masks in crowded public areas
3. Voluntary social distancing

I don’t believe any of those three policies would be sufficient, considered in isolation. But we have more and more evidence from countries all over the world that major gains can be achieved by utilizing all three in combination.

The goal in many countries (not Sweden!) is to get the “R0” reproduction rate below 1.0. Every effective practice that reduces R0 can push us closer to that goal, even if that individual step not enough. So I’m not persuaded when a skeptic tells me that masks alone won’t do the job, or testing alone won’t do the job. There are now some pretty populous countries that have essentially zero community transmission and where restaurants and stores are open for business. Of course, even in those countries things are far from perfect. But there are much worse outcomes that South Korea, and we have one of those much worse outcomes in the US.

PS.  All of the countries I considered in my April “Islands” post continue to make great progress.  Furthermore, an ever-growing number of countries are making substantial progress, despite not reducing community transmission to zero.  Thus active caseloads are falling very rapidly in places like Austria, Germany and Switzerland (and perhaps Norway, although their active caseload data is not updated.)  I’m not as confident of the continued success of those places because they still have very caseloads, and also closer links with other countries than the island success stories.  But they are worth watching.

The US continues to see its active caseload skyrocket (today it reached 1 million).  In early April, we had 5 times as many active cases as Germany.  Now we have nearly 50 times as many.  We seem unsure as to whether to try to control the disease or to go for herd immunity, and thus are ending up with the worst of both worlds—lots of new cases and deaths, and a crashing economy.