SARS-CoV-2 infection prevalence in people experiencing homelessness

People experiencing homelessness have peculiar characteristics that make them more vulnerable to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission and to more serious forms of Coronavirus Disease 19 (COVID-19). The aim of this study was to evaluate the prevalence of SARS-CoV-2 infection in the homeless population assisted by the primary care services of the Eleemosynaria Apostolica, Vatican City.

Persons experiencing homelessness and the volunteers assisting them were tested for COVID-19 through PCR and antigen rapid test between October 1st, 2020, and June 5th, 2021, in the clinical facilities of the Eleemosynaria Apostolica.

A total of 1665 subjects from 96 different countries in five continents were included in the study; age range was 1-90 years. Overall, 2315 COVID-19 tests through nasopharyngeal swab were performed; 1052 Polymerase Chain Reaction (PCR) tests and 1263 antigen rapid tests. Nearly 40% of the subjects underwent both tests (n=650, 39.04%), 402 were tested with PCR test only (24.14%) and 613 with antigen test only (36.8%). PCR tests were negative in 966 cases and positive in 86 (8.17%), while antigen tests were negative in 1205 cases and positive in 58 (4.59%). The number of positive cases varied over time, with a drastic increase during the winter months of 2020 and a progressive decrease over 2021. Among positive cases, 24.41% were symptomatic; symptoms included fever, breathing difficulties, anosmia/hyposmia, cough, headache, and diarrhea.

This study reported an overall prevalence of SARS-CoV-2 infection in our sample slightly above 8%. Additional data on viral genome through sequencing of SARS-CoV-2 in positive cases are of utmost importance to help identify variants and implement specific infection control measures.