There are no known major outbreaks yet in prisons and jails, though that may reflect the absence of testing, not the absence of covid-19, in the facilities. Many of them are perfect incubators for the disease, housing packed-in populations more likely than other Americans to have a chronic condition or infectious disease. Social distancing, the most effective means of impeding the spread of the virus, is all but impossible at most prisons and jails. Overcrowding; broken sinks; unreliable soap supplies; a steady influx of new inmates; and, at many institutions, substandard medical care — these are the ingredients that could all too easily fuel the pandemic behind bars.

Some 2.2 million prisoners are in U.S. prisons and jails. They are in danger; so are hundreds of thousands of corrections officers and others who work in such institutions and then circulate in their communities. All of them need timely and complete information on protocols and best practices for contending with the virus.