Prevalence and features of SARS-CoV-2 infection in prisons in Tuscany

Prisons can be a reservoir for infectious diseases, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), due to the very intimate nature of the living spaces and the large number of people forced to share them.

To investigate the SARS-CoV-2 epidemiology in prisons, this study evaluated the infection incidence rate in prisoners who underwent nasopharyngeal swabs.

This is an observational cohort study. Data collection included information on prisoners who underwent nasopharyngeal swab testing for SARS-CoV-2 and the results. Nasopharyngeal swab tests for SARS-CoV-2 were performed between 15 February 2021 and 31 May 2021 for prisoners with symptoms and all new arrivals to the facility. Another section included information on the diagnosis of the disease according to the International Classification of Diseases, Ninth Revision, and Clinical Modification.

Up until the 31 May 2021, 79.2% of the prisoner cohort (n = 1744) agreed to a nasopharyngeal swab test (n = 1381). Of these, 1288 were negative (93.3%) and 85 were positive (6.2%). A significant association [relative risk (RR)] was found only for the risk of SARS-CoV-2 infection among foreigners compared to Italians [RR = 2.4, 95% confidence interval (CI): 1.2-4.8]. A positive association with SARS-CoV-2 infection was also found for inmates with at least one nervous system disorder (RR = 4, 95%CI: 1.8-9.1). The SARS-CoV-2 incidence rate among prisoners is significantly lower than in the general population in Tuscany (standardized incidence ratio 0.7, 95%CI: 0.6-0.9).

In the prisoner cohort, screening and rapid access to health care for the immigrant population were critical to limiting virus transmission and subsequent morbidity and mortality in this vulnerable population.