The paper attempts to model various scenarios (containment, treatment, medical readiness, vaccine, etc.). Here (below) is the abstract, which reports “the benchmark scenario.” Estimates of other scenarios are in the paper. Of course, the model parameters lack the hard data (e.g., experimental data) that Dr. Kling seeks about contagion mechanisms:

“The Macroeconomics of Epidemics
Martin S. Eichenbaum, Sergio Rebeloy, and Mathias Trabandtz
March 20, 2020
Abstract
We extend the canonical epidemiology model to study the interaction between economic decisions and epidemics. Our model implies that people’s decision to cut back on consumption and work reduces the severity of the epidemic, as measured by total deaths. These decisions exacerbate the size of the recession caused by the epidemic. The competitive equilibrium is not socially optimal because infected people do not fully internalize the effect of their economic decisions on the spread of the virus. In our benchmark scenario, the optimal containment policy increases the severity of the recession but saves roughly 0.6 million lives in the U.S.”

The authors emphasize that the models don’t include some key factors (basically factors that Dr. Kling has highlighted in various blogposts):

“we note that our model abstracts from various forces that might affect the long-run performance of the economy. These forces include bankruptcy costs, hysteresis effects from unemployment, and the destruction of supply-side chains. It is important to embody these forces in macroeconomic models of epidemics and study their positive and normative implications.”

As I said, I would “add” lack of vaccine to his answer for #1, not replace the original. The relatively high fatality rate could fit there too.

If there had been a vaccine produced immediately when this thing broke in Wuhan, and administered to the same number of Americans as the flu shot, do you think anything would be shut down right now in the US? Even at ~50% efficacy, that would significantly slow the spread, and most would feel protected enough to lead normal daily lives, with maybe a little extra hand washing. People would still get sick and die, but people would have much more confidence in containment.

But still, I think part of the worry about cov is that no one is vaccinated, so there’s no herd immunity to slow down the spread. The flu shot mostly protects you (imperfectly) and partly protects others by reducing the chance you will spread it. No such option here yet.

1) exponential growth in confirmed cases continues for the next 1-2 weeks while testing catches up, even if social distancing is slowing down the true infection rate. This will lead people to claim that it isn’t working

2) eventually, the effects of social distancing (and possibly warmer weather) will slow down the growth. Those who were against shutting things down will claim that it was all overblown the whole time and it was going to slow down anyway.

Many of the commentariat are senior academics, public officials, executives, etc., age 60+ so, while not necessarily really elderly retirees, perhaps at somewhat elevated risk. Many of the young commentariat, say progressive woke journalists, are infatuated with the idea that Americans’ excessive commercialism needs to be tempered by Lenten-like rituals of abstinence and atonement. This could be an example of Bootleggers and Baptists.