On May 30, 120 prisoners were transferred from a prison in Chino, California, to San Quentin, just north of San Francisco. A week later, 15 of them had tested positive for COVID-19, the first outbreak in that prison.
San Quentin employees have said that some of those transferred had not been tested in the month prior to transfer, and that some were showing symptoms in transit. State assembly member Marc Levine called the transfer "botched." Experts had advised frequent testing of staff and inmates and timing releases and transfers to isolate cases, advice not followed until after the actual outbreak. Poor ventilation and overcrowding have also contributed to the outbreak.