Rapid Spread of SARS-CoV-2 in a State Prison After Introduction by Newly Transferred Incarcerated Persons - Wisconsin, August 14-October 22, 2020

Abstract

SARS-CoV-2, the virus that causes COVID-19, can spread rapidly in prisons and can be introduced by staff members and newly transferred incarcerated persons (1,2). On September 28, 2020, the Wisconsin Department of Health Services (DHS) contacted CDC to report a COVID-19 outbreak in a state prison (prison A). During October 6-20, a CDC team investigated the outbreak, which began with 12 cases detected from specimens collected during August 17-24 from incarcerated persons housed within the same unit, 10 of whom were transferred together on August 13 and under quarantine following prison intake procedures (intake quarantine). Potentially exposed persons within the unit began a 14-day group quarantine on August 25. However, quarantine was not restarted after quarantined persons were potentially exposed to incarcerated persons with COVID-19 who were moved to the unit. During the subsequent 8 weeks (August 14-October 22), 869 (79.4%) of 1,095 incarcerated persons and 69 (22.6%) of 305 staff members at prison A received positive test results for SARS-CoV-2. Whole genome sequencing (WGS) of specimens from 172 cases among incarcerated persons showed that all clustered in the same lineage; this finding, along with others, demonstrated that facility spread originated with the transferred cohort. To effectively implement a cohorted quarantine, which is a harm reduction strategy for correctional settings with limited space, CDC's interim guidance recommendation is to serial test cohorts, restarting the 14-day quarantine period when a new case is identified (3). Implementing more effective intake quarantine procedures and available mitigation measures, including vaccination, among incarcerated persons is important to controlling transmission in prisons. Understanding and addressing the challenges faced by correctional facilities to implement medical isolation and quarantine can help reduce and prevent outbreaks.

FIGURE 1

Number of COVID-19 cases among incarcerated persons (A) (n = 869) and staff members (B) (n = 69), by testing date — prison A, Wisconsin, August 14–October 22, 2020 * Modified lockdown refers to prison A’s policy change that restricted movement of incarcerated persons within the facility and shut down all areas except for food services. Total lockdown refers to prison A’s policy change that restricted outdoor recreation and limited movement within housing units by modifying daily operations to allow incarcerated persons to leave their cells only in small groups during assigned time slots for shower and telephone time. Meals were delivered and eaten within cells.

FIGURE 2

Phylogenetic tree showing genetic distance between available SARS-CoV-2 specimens from prison A, a central intake facility, and the surrounding communities — Wisconsin, June–December 2020 * Includes 230 of 1,345 sequences produced by Wisconsin State Laboratory of Hygiene during June–December 2020 using the ARTIC sequencing approach (https://artic.network/ncov-2019) on both the Illumina MiSeq and Oxford Nanopore MinION platforms. Consensus sequences generated using the StaPH-B ToolKit Monroe workflow v1.2.5 (https://github.com/StaPH-B/staphb_toolkit). Phylogenetic inference and visualization performed using Nextstrain Augur v9.0.0 (https://github.com/nextstrain/augur) and Nextstrain Auspice v2.18.4 (https://github.com/nextstrain/auspice). ^† Clusters A and B refer to sequences from specimens collected at prison A. Cluster A refers to sequences from specimens collected at prison A that showed a genetic relationship with 29 sequences collected from a concurrent outbreak at the central intake facility. Cluster C refers to sequences from specimens collected outside of the outbreaks at the central intake facility and at prison A. ^§ No specimens from staff members were available for sequencing because the testing laboratory had discarded them.