A time-series analysis of testing and COVID-19 outbreaks in Canadian federal prisons to inform prevention and surveillance efforts

Abstract

Background: Approximately 14,000 adults are currently incarcerated in federal prisons in Canada. These facilities are vulnerable to disease outbreaks and an assessment of coronavirus disease 2019 (COVID-19) testing and outcomes is needed. The objective of this study was to examine outcomes of COVID-19 testing, prevalence, case recovery and death within federal prisons and to contrast these data with those of the general population.

Methods: Public time-series outcome data for prisoners and the general population were obtained on-line from the Correctional Service of Canada and the Public Health Agency of Canada, respectively, from March 30 to May 27, 2020. Prison, province and sex-specific frequency statistics for each outcome were calculated. A total of 50 facilities were included in this study.

Results: Of these 50 facilities, 64% reported fewer individuals tested per 1,000 population than observed in the general population and 12% reported zero tests in the study period. Testing tended to be reactive, increasing only once prisons had recorded positive tests. Six prisons reported viral outbreaks, with three recording over 20% cumulative COVID-19 prevalence among prisoners. Cumulatively, in prisons, 29% of individuals tested received a positive result, compared to 6% in the general population. Two of the 360 cases died (0.6% fatality). Four outbreaks appeared to be under control (more than 80% of cases recovered); however, sizeable susceptible populations remain at risk of infection. Female prisoners (5% of the total prisoner population) were over-represented among cases (17% of cases overall).

Conclusion: Findings suggest that prison environments are vulnerable to widespread severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Gaps in testing merit public health attention. Symptom-based testing alone may not be optimal in prisons, given observations of widespread transmission. Increased sentinel or universal testing may be appropriate. Increased testing, along with rigorous infection prevention practices and the potential release of prisoners, will be needed to curb future outbreaks.

Keywords: COVID-19; Canada; disease outbreak; prisoners; prisons.

Figure 1

Cumulative totals of individuals tested per 1,000 population, test-positive rate, case prevalence and proportion recovered for Canadian federal prisons as of May 27, 2020^a,b Abbreviations: AB, Alberta; BC, British Columbia; CAN, Canada; MAN, Manitoba; NB, New Brunswick; NS, Nova Scotia; ONT, Ontario; QC, Québec; SASK, Saskatchewan ^a Missing test-positive, prevalence and recovered proportions indicate an absence of cases as of May 27, 2020 ^b Error bars reflect estimate bounds based on 100% to 70% of maximum prison capacity levels, with central estimates based on 85% occupancy, (exact population counts were not available publicly or following request)

Figure 2

Cumulative totals of individuals tested per 1,000 population, test-positive rate, case prevalence and proportion recovered for federal prison and general populations, by province, as of May 27, 2020^{a a} Error bars reflect estimate bounds based on 100% to 70% of maximum prison occupancy levels, with central estimates based on 85% occupancy (exact population counts were not available publicly or following request)

Figure 3

Timeline of cumulative total of individuals tested per 1,000 population in federal prisons and the general population, by province, from March 30 to May 27, 2020^{a a} Circular line makers indicate the dates at which data were captured from web-based archives of the Correctional Services Canada’s webpage. Error bars reflect estimate bounds based on 100% to 70% of maximum prison capacity levels, with central estimates based on 85% occupancy, (exact population counts were not available publicly or following request)

Figure 4

Testing patterns and outcomes between March 30 and May 27, 2020, in six prisons with one or more recorded COVID-19 cases^a Abbreviations: BC, British Columbia; ON, Ontario; QC, Québec ^a Only dates for which data was captured from web-based archives of Correctional Service of Canada’s webpage are indicated. The drop in cumulative negative tests in Joliette and Grand Valley Women’s facilities and total cumulative tests at Port Cartier facility may appear as erroneous but represent true values reported by Correctional Service of Canada

Figure 5

Number of susceptible prisoners, infected prisoners, recovered cases and deaths between March 30 and May 27, 2020, in Canadian federal prisons with one or more recorded COVID-19 cases^a Abbreviations: BC, British Columbia; ON, Ontario; QC, Québec ^a Line makers indicate the dates at which data were captured from web-based archives of the Correctional Service of Canada’s webpage. Error bars reflect estimate bounds based on 100% to 70% of maximum prison capacity levels, with central estimates based on 85% occupancy, (exact population counts were not available publicly nor following request)