Nearly half of all inmates in South Dakota have tested positive for COVID-19 as of Monday, The Argus Leader reports. At one facility, the Mike Durfee State Prison, two out of every three inmates have the virus. Another, the Sioux Falls Community Work Center, reported having over 100 cases, the fourth in the state to do so. In total, 1,555 of the state’s 3,347 inmates have tested positive, nearly half of the prison population. The decision by South Dakota’s Departments of Corrections and Health to start mass testing has revealed this spike in positive case rate. The departments intend to continue conducting monthly sentinel surveillance testing of five percent of asymptomatic inmates and staff.