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Notes from the Field: COVID-19 Prevention Practices in State Prisons – Puerto Rico, 2020

Our take —

This study reported on results of a new protocol for channeling incoming prisoners through a standardized protocol of testing and quarantine. In contrast to the mass outbreaks seen in many other U.S. correctional facilities, only two cases were observed after initiation of the new protocol. Rigorous testing and isolating of incoming prisoners, limiting sharing of common facilities in prisons, and isolation of anyone who develops symptoms, is an effective way to reduce SARS-CoV-2 transmission in a high-risk congregate setting.

Study design


Study population and setting

In mid-March 2020, the Puerto Rico Department of Health implemented a protocol to prevent and manage COVID-19 in all publicly-run prisons in Puerto Rico based on interim guidance from the CDC. This study reports on test results among all 1,340 newly incarcerated people in Puerto Rico from March 16 to July 31, 2020, after implementation of the new protocol. The new protocol focused on: (i) revised intake procedures for newly incarcerated persons and returning prisoners; (ii) limited sharing of common areas in facilities; and (iii) isolation of any symptomatic persons. Newly incarcerated persons were all processed at one location, and everyone, regardless of symptoms, was tested using RT-PCR. People were then separated into groups of no more than 20. If everyone in the group tested negative, and no one developed symptoms during 14 days of quarantine, then the group was permitted to enter the general prison population. Anyone testing positive or with other health issues/symptoms was isolated and taken to the prison medical facility, prompting a reset of the entire process. Any incarcerated person leaving the prison was required to undergo the intake process upon return. The general prison population was separated into groups of 40-75 people with each group having their own common areas. Any individual that developed symptoms was promptly isolated and the rest of the group quarantined. In May, all willing incarcerated persons were tested using a point-of-care antibody test to test for previous and recent/active infection.

Summary of Main Findings

The revised protocol appears to have been successful at preventing transmission in incarcerated populations. Between March and July, 2020 1,340 newly incarcerated persons went through the revised intake protocol, with two people testing positive during the initial intake process. Based on the serologic testing in May, 0.3% (31 out of 8,619) tested positive for IgG antibodies to SARS-CoV-2 (indicating past infection); no one tested positive for IgM antibodies (indicating a recent/active infection).

Study Strengths

The study provides a comprehensive description of protocols used to limit the spread of COVID-19 amongst a network of prisons. Mass serologic testing provided an estimate of prevalence of recent and past infection.


Despite serologic testing being offered to every incarcerated adult, no detail was provided on the number who opted out of testing, making it difficult to assess how effective the protocol was. The sensitivity and specificity of the antibody test was not reported; the specificity is of particular interest in this setting of apparently low prevalence. For implementation purposes, details of additional resource requirements (e.g. staffing, financing) would have been useful. No data were provided on incidence or prevalence of SARS-CoV-2 infection in either the general population of Puerto Rico or in a subpopulation with similar demographic characteristics as the newly incarcerated inmates. Elements of the protocol may not be applicable to settings with higher population density, where cohorting into small groups is impractical.

Value added

The authors describe, in detail, practical ways to reduce SARS-CoV-2 transmission in prison facilities in Puerto Rico.

This review was posted on: 27 September 2020