Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals

TLDR

COVID‑19 has spread rapidly worldwide, and while droplet and contact transmission are established, aerosol transmission remains poorly understood. The study aimed to investigate the aerodynamic characteristics of SARS‑CoV‑2 by measuring aerosolized viral RNA in various hospital areas and to assess the potential for aerosol transmission, with future work to evaluate infectivity. Viral RNA was quantified in aerosols collected from isolation wards, ventilated patient rooms, toilet areas, public spaces, and staff areas in two Wuhan hospitals during February–March 2020. SARS‑CoV‑2 RNA was detected at low levels in isolation wards and ventilated rooms, higher in patient toilet areas, undetectable in most public spaces except crowded zones, and initially high in staff areas but fell to undetectable after rigorous sanitization, indicating that ventilation, open space, and sanitation effectively reduce aerosol RNA concentrations.

Abstract

The ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread rapidly on a global scale. Although it is clear that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted through human respiratory droplets and direct contact, the potential for aerosol transmission is poorly understood1-3. Here we investigated the aerodynamic nature of SARS-CoV-2 by measuring viral RNA in aerosols in different areas of two Wuhan hospitals during the outbreak of COVID-19 in February and March 2020. The concentration of SARS-CoV-2 RNA in aerosols that was detected in isolation wards and ventilated patient rooms was very low, but it was higher in the toilet areas used by the patients. Levels of airborne SARS-CoV-2 RNA in the most public areas was undetectable, except in two areas that were prone to crowding; this increase was possibly due to individuals infected with SARS-CoV-2 in the crowd. We found that some medical staff areas initially had high concentrations of viral RNA with aerosol size distributions that showed peaks in the submicrometre and/or supermicrometre regions; however, these levels were reduced to undetectable levels after implementation of rigorous sanitization procedures. Although we have not established the infectivity of the virus detected in these hospital areas, we propose that SARS-CoV-2 may have the potential to be transmitted through aerosols. Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concentration of SARS-CoV-2 RNA in aerosols. Future work should explore the infectivity of aerosolized virus.