Distributions and risks of SARS-CoV-2 in hospital outdoor environment

The outbreak of coronavirus infectious disease-2019 (COVID-19) pneumonia since 2019 has rapidly spread throughout over 200 countries around the world. Till 14th May 2020, there are over 4 million confirmed cases and 300,000 deaths globally. To date, numerous studies focus on the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in indoor areas for its main transmission routes via human respiratory droplets and direct contact. It remains unclear about the distribution and transmission risks of SARS-CoV-2 in outdoor environment despite its threats to healthy people and communities. Here, we investigated the presence of SARS-CoV-2 virus in 73 specimens from outdoor environment of three hospitals in Wuhan. We found SARS-CoV-2 in soils (205-550 copies/g), wastewaters (255 to 1.9×104 copies/L) and aerosols (285-1130 copies/m3) in locations close to departments receiving COVID-19 patients or in wastewater treatment sectors, which revealed significant viral spill-over in hospital outdoor environment that was possibly via respiratory droplets from patients or airborne aerosols from wastewater containing SARS-CoV-2. In contrast, SARS-CoV-2 was not detected in other areas or on surfaces with regular disinfection. Soils eventually behave as viral receptors through deposition and potentially a secondary source spreading SARS-CoV-2 for a prolonged time. Our findings map the high-risk areas in hospital outdoor environment possessing spread risks of SARS-CoV-2, which require particular attention and complete sanitation for preventing SARS-CoV-2 outdoor transmission.