SAN FRANCISCO (CBS SF) — The San Francisco Sheriff’s Office confirmed that a second sworn staff member assigned to the Hall of Justice tested positive for COVID-19 Thursday.

The Sheriff said it is not yet known where the employee may have contracted the virus.

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“We are testing both staff and justice-involved people in our custody to identify and isolate individuals who are infected,” said Sheriff Paul Miyamoto in a press release issued Thursday afternoon. “Given the spread of the virus and the prevalence of asymptomatic positive cases, there are bound to be positive results. We follow up immediately with contact tracing, alerting people who may have been exposed and could potentially expose others. This is how we prevent further spread.”

“The risk of transmission is mitigated with Sheriff’s Office policies that include physical distancing, masking at all times and frequent hand washing,” added Dr. Lisa Pratt, the San Francisco Director of Jail Health Services.

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A total of ten employees with the Sheriff’s Office have tested positive for COVID-19 during the pandemic. Five staff members tested positive in March 2020. Five more employees have tested positive in July including this new case and a Sheriff’s bailiff who tested positive on July 16.

Authorities said two of the five staff members who tested positive in July were away from work for an extended period when they tested positive. Additionally, an asymptomatic Sheriff’s employee assigned to the Laguna Honda campus also tested positive earlier this week.

Earlier Thursday, San Francisco health officials announced they would be opening up a continuing medical care facility in the Presidio to allow for more beds to be freed up in local hospitals to handle the current surge.

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San Francisco — which remains on the state COVID-19 watchlist — currently has 6,423 patients diagnosed with COVID-19. A surge in April put 94 San Franciscans in the hospital; the number dipped to 26 six weeks ago. As of Thursday, there were 107 City residents in the hospital. One quarter of them are in intensive care.