How Prisons, Very Much Like Nursing Homes, Helped Spread COVID Beyond Their Walls

After a botched inmate transfer, San Quentin guards carried the virus back to their neighborhoods

The mistakes made by the California prisons system during a May 2020 inmate transfer are well documented now, a case study of how not to manage close populations during a pandemic. Abandoning testing protocols and medical advice, prison authorities packed 189 medically vulnerable inmates from a COVID-ravaged facility near Los Angeles onto buses for hourslong trips to San Quentin and Corcoran prisons. 

Inevitably, already-infected transferees brought COVID-19 with them. The subsequent outbreak at San Quentin sickened more than two-thirds of its population, ultimately killing 28 inmates and one staff member. The state’s official investigation excoriated the transfer plan as deeply flawed, risking “the health and lives of thousands of incarcerated persons and staff.”

Turns out, the public outside the prison walls also had much at stake in that botched transfer, according to a paper published in PNAS Nexus. Using smartphone location and disease tracking data, researchers find that San Quentin’s staff carried a lot of COVID-19 home in those post-transfer months. The subsequent outbreaks in their own communities were larger than those in demographically similar neighborhoods without the prison workers, according to findings by Balbec Capital’s Yilin Zhuo, UCLA Anderson’s M. Keith Chen, and University of California, Irvine’s Kristin Turney and Emily Owens, and UCLA’s Naomi F. Sugie.

Prison Protocols, Everyone’s Problem

The findings are a reminder that disease control decisions, even when made for prisons, matter for everyone. When masking, testing and quarantine protocols are lax, or simply exclude staffers who go home after the shift, outsiders get sick too, the study finds. Other research around COVID-19 in nursing homes has reached similar conclusions.

Neighborhoods housing San Quentin staff reported 10% more COVID-19 cases in July 2020 and 30% more in August 2020 than matched neighborhoods that did not, the study finds. Outside of these months, the similar but unconnected neighborhoods had reported the higher COVID-19 rates. The study design suggests prison staff, rather than visitors or released inmates, as the likely vectors.  

The researchers also ran a hypothetical scenario involving a new respiratory disease at eight other California prisons that had significant COVID-19 outbreaks. Assuming it spread at the rate San Quentin experienced, staff movements alone from these eight prisons led to roughly 15,000 new cases in their communities in the first month and nearly 20,000 within two months, according to the analysis. 

The researchers point out that actual case numbers would have been much higher, as this study does not track disease beyond first generation spread. The findings do not, for example, capture infections that likely occurred when a guard infected their partner, who then went to the grocery store, child care center or a job in a different ZIP code. 

Transfer prisoners also sparked a COVID-19 outbreak at Corcoran, although solid doors on cells there are thought to have limited the spread, the researchers write. Their more cursory analysis of worker movements from there — there was not as much available data on where Corcoran staff lived — finds slightly larger rates of staff transmission into the communities than from San Quentin, according to the study.

The Patient Zero Conundrum

A big problem with trying to peg the source of disease outbreak is the overwhelming number of potential vectors that run both ways. Kid’s birthday party? It’s hard to tell if Uncle Bob brought COVID-19 or was infected there by someone else. The issue multiplies many times over at, say, a hospital, where any number of patients, vendors, staff, sales reps and visitors could be the original carrier. 

The San Quentin outbreak is useful, the researchers explain, because its source was pretty clear; 15 of those bus transferees tested positive for COVID-19 immediately after arriving at San Quentin. The rest were housed in a unit without solid doors, overseen by staff members who worked units inside the area and beyond. Case numbers inside skyrocketed right on time after the new arrivals. California prisons were not allowing visitors at the time.

The researchers first identified 93 ZIP codes “connected” to San Quentin using location data from smartphones that spent long hours inside the prison and also stayed for hours (likely slept) in nearby communities. They compared outcomes in these communities with those in matched communities with similar demographics, and roughly similar COVID-19 trends, but no connection to San Quentin. Some of the unconnected communities were hundreds of miles away. 

The tracked devices likely were carried by prison staff, the study explains. Inmates generally didn’t come from nearby ZIP codes. For a crosscheck, the researchers also looked at a public database called LODES to see where (which census tract) San Quentin workers lived. Those records are unique to California correction officers and do not identify individual workers. 

During the pandemic, public outcry over COVID-19 inside nursing homes sparked federal regulations around protocols and staffing orders, as well as emergency shipments of personal protection equipment and other emergency supplies.

In prisons, rates of COVID-19 were five times higher than in the general population, death rates were triple and safety protocols like distancing were sometimes all but impossible.That population got little attention from Washington and virtually no additional resources. But it appears that even unpopular causes can be serious public health threats.