Asymptomatic patients as a source of transmission of COVID-19 in homeless shelters

Objectives: Asymptomatic carriers account for over a third of all Coronavirus Disease 19 (COVID-19) cases and are characterized by the absence of symptoms but the same infectivity as symptomatic infections. The high percentage of asymptomatic COVID-19 patients is significant in settings with specific vulnerabilities, such as homeless shelters, where the consequences of an outbreak may be dramatic. In this work, we briefly report our experience on residents and staff of homeless shelters in the City of Rome, Italy, with a particular focus on asymptomatic transmission, and compare it with the available evidence. Methods: We performed routine Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) nasopharyngeal swab tests in all residents and staff of homeless shelters managed by the Eleemosynaria Apostolica of the Vatican City State in the city of Rome, Italy, in addition to daily symptom screening, body temperature monitoring, and application of other prevention measures. Results: We evaluated 298 persons and identified twelve positive cases (4%). Most of the positive cases (75%) were asymptomatic, while only three patients reported symptoms that included fever, diarrhea, and cough. Conclusions: Our data confirm the importance of early identification of asymptomatic carriers that could, in vulnerable conditions such as homeless shelters, spread the infection and cause outbreaks with severe consequences on individual and public health.