SEROPREVALENCE and RISK FACTORS for SARS-CoV-2 among INCARCERATED ADULT MEN in QUEBEC

ABSTRACT

Background: People in prison are at increased risk of SARS-CoV-2 infection due to overcrowding and the challenges in implementing infection prevention and control measures;however, seroprevalence studies are lacking in correctional settings. We examined the seroprevalence of SARS-CoV-2 and associated modifiable risk factors among incarcerated adult men in Quebec, Canada. Methods: We conducted a cross-sectional seroprevalence study in three provincial prisons, representing 45% of Quebec's incarcerated male provincial population. The primary outcome was SARS-CoV-2 antibody seropositivity, detected by the Roche Elecsys® anti-SARS-CoV-2 serology test. Participants completed self-administered questionnaires on sociodemographic, clinical, and carceral characteristics. The association of carceral variables with SARS-CoV-2 seropositivity was examined using Poisson regression models with robust standard error. Crude and adjusted prevalence ratios (aPR) with 95% confidence intervals (95%CI) were calculated. Results: Between January 19 and September 15, 2021, 246 of 1,100 (22%) recruited individuals tested positive across three prisons (range 15-27%). Of these, 192 (78%) reported having at least one previous SARS-CoV-2 PCR test, with 122 (64%) testing positive and 70 (36%) testing negative;73 (30%) individuals with a positive serology test were asymptomatic. Seropositivity increased with time spent in prison since March 2020 (aPR 2.17, 95%CI 1.53-3.07 for all vs. little), employment during incarceration (aPR 1.64, 95%CI 1.28-2.11 vs. not), shared meal consumption during incarceration (with cellmates aPR 1.46, 95%CI 1.08-1.97 vs. alone;with sector aPR 1.34, 95%CI 1.03-1.74 vs. alone), and incarceration post-prison outbreak (aPR 2.32, 95% CI 1.69-3.18 vs. pre-outbreak) (see Table). Shared (vs. single) cells were not associated with increased seropositivity. Conclusion: The seroprevalence of SARS-CoV-2 among incarcerated individuals was high and varied between prisons. Several modifiable carceral factors were associated with seropositivity, underscoring the importance of decarceration and occupational safety measures, individual meal consumption, and enhanced infection prevention and control measures including vaccination during incarceration.