Abstract View
Measuring Short Time Course Reduction of SARS-CoV-2 Infectivity in Aerosol
HENRY OSWIN, Allen E. Haddrell, Mara Otero, Jamie Mann, Tristan Cogan, Andrew Davidson, Jonathan P. Reid, University of Bristol
Abstract Number: 326
Working Group: Bioaerosols
Abstract
The COVID-19 pandemic has been a major source of mortality and morbidity across the globe, as well as imparting a significant economic burden. Yet a year into this pandemic there remain many questions surrounding the transmission dynamics of SARS-CoV-2. New research tools are needed to provide a more detailed picture of the factors influencing the airborne and droplet borne transmission of disease.
A novel method was developed at the University of Bristol for the airborne study of bacteria (Fernandez, 2019) and has been adapted for the study of viruses in a BSL-3 laboratory. Using electrodynamic levitation, virus containing droplets of controllable size and composition can be suspended within a humidity (RH 5-95%) and temperature (0 C – 50 C) controlled chamber. The droplets can be suspended from 5 seconds to days or even weeks and are then extracted from the chamber allowing the virus within to be quantified by cytopathic effect.
Using this technique, it was determined that the airborne stability of SARS-CoV-2 in culture media droplets was linked to the physical state of the droplet. If the relative humidity was below 50% the droplet effloresced, forming a dry crystalline particle, which caused the infectivity of the virus to almost immediately drop by up to 60%. At high enough RH's to keep the droplet remaining liquid, the virus underwent a more gradual drop in infectivity. For example, at 90% RH SARS-CoV-2 took over 5 minutes to reach a 60% drop in infectious virus. But the rate of viral decay in the liquid droplet does not slow down as much as the dry particle meaning that after 10 minutes the infectivity of the virus was similar at both high and low RH.
These measurements are significantly more refined than previously reported data from rotating drum measurements (Van Doremalen 2020) and cover a much wider range of environmental conditions. The data provides an insight into potential seasonal and geographical impacts on COVID-19 transmission dynamics, as well as information that may aid the development of new infection control procedures.