Federal Prisoners and COVID-19: Background and Authorities to Grant Release [Updated April 23, 2020] [open pdf - 1MB]
From the Summary: "There is concern that coronavirus disease 2019 (COVID-19) could quickly spread among federal prisoners and prison staff because of the nature of the prison environment. Prisons are places where hundreds of prisoners and staff are living and working in close proximity to each other and where they are forced to have regular contact. Prisons are generally not conducive to social distancing. Also, prison infirmaries typically do not have the resources available to most hospitals, such as isolation beds, that would help prevent the spread of the disease. There are also concerns that if prison staff were hard hit by COVID-19, a significant number of staff would require quarantine; they would be unavailable to perform their duties, including providing care to sick prisoners; and the disease could spread."
CRS Report for Congress, R46297
Congressional Research Service: https://crsreports.congress.gov/