SAN FRANCISCO, Calif. (KRON) — The second-worst coronavirus outbreak in the U.S. is right in San Francisco’s backyard. Infectious disease physician Peter Chin Hong describes the situation happening inside San Quentin State Prison as a “volcano erupting in our neighborhood.”

Even though patients are behind prison walls, the virus can still spread into Bay Area communities through corrections officers, nurses, and others who come and go from the facility, healthcare professionals warn.

More than 700 healthcare workers, including many who are based at the University of California San Francisco, signed an open letter and petition to Gov. Gavin Newsom and the Department of Corrections and Rehabilitation this week urging for more inmates to be released. Lowering the inmate population to below 50 percent of capacity is the most effective way to make conditions possible for slowing the virus’ spread, they said.

“While we applaud the recent decision to release 8,000 individuals, this action is woefully insufficient to address the crisis we now face,” the letter states.

The letter states, “This is a public health crisis — one that impacts not only those Californians who are currently experiencing incarceration, but all of us.  Crowded prisons and jails serve as incubators of disease. The rampant spread within prisons causes preventable morbidity and mortality, not only for residents, but for staff, their families, and the surrounding community.”

San Quentin has 500 active cases. Not long ago, it had 0. That was changed by a disastrous decision made with good intentions, Dr. Chin Hong said. A prison in Chino, Calif. was having an outbreak, so it transferred about 100 of its inmates to San Quentin to relieve overcrowding. Some of those inmates carried the virus with them to Marin County.

Chin Hong said that decision is now an example of exactly “what not to do” during an outbreak like COVID-19.

State officials need to “really limit transfers between prisons, because that’s how we got to the San Quentin volcano. It was because of a transfer that came, bringing COVID from Southern California to Northern California,” he said.

Four more inmates died in the prison over the weekend from COVID-19 complications. Ten men on San Quentin’s Death Row have died from the virus.

Death by Virus: Condemned San Quentin Inmates ‘executed’ by COVID-19

A view of a new emergency care facility that was erected to treat inmates infected with COVID-19 at San Quentin State Prison. (Photo by Justin Sullivan/Getty Images)