Tackling COVID-19 Among Prison Populations in California and Beyond

The SHP prison project team is out with two more studies to help prisons prevent and reduce the spread of the coronavirus.
A health-care worker carries COVID-19 vaccines into a prison. Getty Images

California correctional officials have taken steps to mitigate transmission and stem outbreaks of COVID-19 among their prison population — but too many medically vulnerable and older residents are still housed in high-risk settings to allow for a full relaxation of COVID-related restrictions, according to a team of Stanford Health Policy researchers.

And if the virus were inadvertently introduced into any of the 110 federal and 1,822 state prisons that might have resumed normal operations, the infection rates could be alarming. Medical and mostly celled prisons with moderate vaccine coverage and no baseline immunity could see more than 20% of residents infected over a period of 200 days. That figure jumps to nearly 75% of residents in those prisons that have dormitory housing (allowing for more limited social distancing). While the analysis was based on the Alpha variant, even more infections are possible with the more-transmissible Delta. Even with higher levels of vaccination-induced and naturally acquired immunity, outbreak risks persist especially in settings with dormitory housing.

These are the latest findings by a team of Stanford faculty and students who have been using a mathematical model to investigate the epidemiology of the coronavirus since the start of the pandemic. One ongoing project involves working with the California Department of Corrections and Rehabilitation (CDCR) on ways to prevent and reduce the spread of COVID-19 in its facilities, as well as inform mitigation strategies in other high-density living situations.

Their latest findings were published in the Journal of General Internal Medicine and The Lancet Public Health.

Transmission forces can be very strong in prisons throughout the country, crowding and lack of vaccination makes such risks truly dire,
Jeremy Goldhaber-Fiebert
Associate Professor of Medicine

Prison Population

In the first year of the COVID-19 pandemic, U.S. prison populations had infection rates five-to-six-times higher than the general population.

“Overcrowded congregate living spaces, inadequate testing, lack of personal protective equipment and adequate sanitation, mistrust of medical personnel, and policies that disincentivize symptom reporting by people who are incarcerated — all increase outbreak risks in U.S. prisons,” the researchers wrote in The Lancet Public Health study.

“The high transmissibility of the Delta variant implies that outbreaks in prisons and other congregate living spaces could be larger and justify proactive prevention measures,” said Jeremy Goldhaber-Fiebert, PhD, senior author of both papers. He is an associate professor of medicine at Stanford Health Policy and one of the founders of the Stanford-CIDE Coronavirus Simulation Modeling (SC-COSMO) Consortium.

The researchers suggest prisons need a multifaceted approach to prevent and manage further outbreaks if they want to safely resume in-person activities, which are beneficial to the health and wellbeing of incarcerated people but have been curtailed substantially to prevent outbreaks.

“Staff vaccination is crucial for choking one of the main avenues of introduction,” the co-authors write in The Lancet Public Health. According to a UCLA Law project, while 75% of the prison population in California has had at least one vaccine dose, only 57% of the staff have been vaccinated.

“Since the risks of outbreaks are so high once an infection is introduced, continued screening and testing of residents, staff, and visitors is crucial to preventing introductions and limiting outbreak sizes,” said Tess Ryckman, lead author of The Lancet Public Health study and a recent PhD graduate from Stanford Health Policy. “Older and medically vulnerable residents, who are at greater risk of severe outcomes if infected, should receive additional protections beyond vaccine and testing priority, such as lower occupancy housing and additional non-pharmaceutical interventions.”

Prisoners get COVID-19 vaccine Prisoners at the Bolivar County Correctional Facility fill out paperwork as they receive a COVID-19 vaccination administered by medical workers with Delta Health Center on April 28, 2021 in Cleveland, Mississippi.

Residents housed in dorms and working alongside other people are particularly vulnerable, the researchers noted. In fact, the infection rates of incarcerated people living in dormitories were more than double than those living in single- or double-cells.

Their second study, published in the Journal of General Internal Medicine, finds that since the pandemic began, the California prison system has taken “steps to mitigate transmission and stem outbreaks.” Nonetheless, they write, many incarcerated people continued to live in high-occupancy housing participate in labor, putting them at increased risk of infection. In addition to rehousing residents who are particularly vulnerable, and decarcerating some residents from correctional facilities, the Stanford researchers are encouraging state correctional officials to continue to prioritize getting residents and staff vaccinated.

Evidence from a separate study by this research group, recently published in the New England Journal of Medicine, indicates that many residents who were initially hesitant about vaccination changed their minds and accepted vaccination when reoffered.

Forgotten Behind Bars

While the Delta variant drives the fourth wave of the COVID-19 pandemic across the nation, it’s easy to forget the nearly 2.3 million people living in U.S. prisons. Yet more than half a million incarcerated people have been diagnosed with COVID through July — 2,912 of whom have died, according to the CDC COVID Data Tracker, including 195 prison staff.

As of August 5, 2021, California 35 prisons led the nation in total number of cases, according to The Marshall Project, with 49,395 COVID cases among incarcerated people. Texas has the highest number of COVID prison deaths at 273, with California following at 227.

Over the past year, prison systems across the country have taken several steps to mitigate the impact of COVID-19. In California, this included vaccination, testing and symptom screening, closure of many group activities, masking, and population reductions. The researchers found that, through a combination of reduced inflows and early parole and releases, the incarcerated population in California prisons decreased 19.1% — 119,401 residents in March 2020 down to 96,623 in October. However, large outbreaks still occurred and substantial risks remained. While reopening activities such as classes, group therapy, and religious services have clear benefits for residents' wellbeing, the analysis shows that doing so safety requires keeping other precautions in place, even with high levels of vaccination. In most settings, including those with lower-occupancy rooms, reopening without non-pharmaceutical interventions (NPIs) yields outbreak sizes that are twice as large, or more, than if activities are reopening with NPIs kept in place.

Furthermore, vaccines are not “perfectly protective,” said Goldhaber-Fiebert.

“Transmission forces can be very strong in prisons throughout the country, crowding and lack of vaccination makes such risks truly dire,” he said. “Protecting older and medically vulnerable incarcerated people therefore requires a multi-pronged approach that includes vaccination and safe housing with reduced risk exposure.”

Elizabeth Chin, lead author of the JGIM study and a PhD candidate in biomedical data science, notes that prisons remain particularly dangerous settings for COVID-19-related morbidity and mortality, with thousands of vulnerable incarcerated people continuing to be housed in settings where their risk of infection is high.

“As correctional systems continue implementing mitigation strategies such as early release and vaccination, our study highlights the importance of prioritizing both those at highest risk of adverse outcomes following infection, and those most likely to contract and spread the virus,” Chin said.

The other co-authors of both papers are Stanford Health Policy’s Lea Prince, David Studdert, Joshua Salomon and Elizabeth Long (The Lancet Public Health); SC-COSMO co-founders Fernando Alarid-Escudero and Jason Andrews; and David Leidner, a clinical psychologist and researcher for the California Department of Corrections and Rehabilitation.

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