From the Executive Summary: "As the number of cases of COVID-19 [coronavirus disease 2019] in the United States continues to sharply increase, and as city, state, and federal officials take increasingly aggressive moves to contain the virus's spread, it is critical to understand the significant role our nation's more than 2,800 county jails may play in spreading the disease, not just within the facilities, but to vulnerable communities more broadly. In short: more than five million people cycle in and out of our jails each year; over a quarter of million just through the jails in New York State alone. Most spend only a few days or weeks behind bars, but while detained they are confined in close proximity to others and with poor medical care. Moreover, those in jails are not only disproportionately vulnerable to COVID-19 themselves, but they come from--and thus return to--communities with disproportionately vulnerable populations. All these factors combine to make jails powerful vectors of disease."