COVID-19 in the California State Prison System: an Observational Study of Decarceration, Ongoing Risks, and Risk Factors

Abstract

Background: Correctional institutions nationwide are seeking to mitigate COVID-19-related risks.

Objective: To quantify changes to California's prison population since the pandemic began and identify risk factors for COVID-19 infection.

Design: For California state prisons (March 1-October 10, 2020), we described residents' demographic characteristics, health status, COVID-19 risk scores, room occupancy, and labor participation. We used Cox proportional hazard models to estimate the association between rates of COVID-19 infection and room occupancy and out-of-room labor, respectively.

Participants: Residents of California state prisons.

Main measures: Changes in the incarcerated population's size, composition, housing, and activities. For the risk factor analysis, the exposure variables were room type (cells vs. dormitories) and labor participation (any room occupant participating in the prior 2 weeks) and the outcome variable was incident COVID-19 case rates.

Key results: The incarcerated population decreased 19.1% (119,401 to 96,623) during the study period. On October 10, 2020, 11.5% of residents were aged ≥60, 18.3% had high COVID-19 risk scores, 31.0% participated in out-of-room labor, and 14.8% lived in rooms with ≥10 occupants. Nearly 40% of residents with high COVID-19 risk scores lived in dormitories. In 9 prisons with major outbreaks (6,928 rooms; 21,750 residents), dormitory residents had higher infection rates than cell residents (adjusted hazard ratio [AHR], 2.51 95% CI, 2.25-2.80) and residents of rooms with labor participation had higher rates than residents of other rooms (AHR, 1.56; 95% CI, 1.39-1.74).

Conclusion: Despite reductions in room occupancy and mixing, California prisons still house many medically vulnerable residents in risky settings. Reducing risks further requires a combination of strategies, including rehousing, decarceration, and vaccination.

Keywords: COVID-19; SARS-CoV-2; exposures; incarcerated populations; infections; prisons.

Figure 1

CDCR incarcerated population size and average room occupancy over time: Graph shows the change in total prison population size (left) and change in the average number of roommates an individual in that prison has (right), for each of the 35 prisons, color-coded by prison type, and for all prisons combined in black (only right panel), from March 1, 2020 (filled circle), to October 10, 2020 (vertical bar). The outbreak prisons used in the multivariate risk analysis are shown above the dashed line, and remaining prisons are shown below the dashed line.

Figure 2

Biweekly participation in labor and other out-of-room activities by age: Graph shows rolling average participation in activities, defined as whether an individual participated in labor or other activities with at least one other person during any day in the past 2 weeks. Panels show (A) labor participation by age and (B) other participation by age. Data cover all prisons from March 1, 2020, through October 10, 2020.

Figure 3

Adjusted cumulative risk of infection in outbreak prisons: Graphs show the adjusted marginal cumulative risk of infection over 90 days from the start of a prison outbreak for (A) room type and (B) room labor (i.e., whether anyone in the room participated in out-of-room labor). Data includes 90 days follow-up for 9 prisons.