Coronavirus school closings: Don't wait until it's too late

We looked at 43 large cities that carried out some combination of non-pharmaceutical interventions (NPIs): isolating the ill or suspected cases in hospitals or at home; banning public gatherings; in some cases, shutting down roads and railways; and closing schools.

School closing turned out to be one of the most effective firewalls against the spread of the pandemic; cities that acted fast, for lengthy periods of time, and included school closing and at least one other NPI in their responses saw the lowest death rates.

Of course, all NPIs are socially disruptive and should be used only as a last resort, to control infections that are highly transmissible and dangerous, and have high fatality rates. The primary problem with the new coronavirus is that we have never before experienced an outbreak with it, so we do not yet have good, stable numbers to tell us how serious it is.