The dynamics of SARS-CoV-2 infectivity with changes in aerosol microenvironment

• DOI: 10.1073/pnas.2200109119
• Publication Date: 2022-06-28T18:07:48Z
• Authors: Henry P. Oswin; Allen E. Haddrell; Mara Otero-Fernandez; Jamie F. S. Mann; Tristan A. Cogan; Thomas G. Hilditch; Jianghan Tian; Daniel A. Hardy; Darryl J. Hill; Adam Finn; Andrew D. Davidson; Jonathan P. Reid
• Keywords: Infectivity; Aerosolization; Coronavirus

Understanding the factors that influence airborne survival of viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in aerosols is important for identifying routes transmission and value various mitigation strategies preventing transmission. We present measurements stability SARS-CoV-2 aerosol droplets (∼5 to 10 µm equilibrated radius) over timescales spanning 5 s 20 min using an instrument probe a small population (typically 10) containing ∼1 virus/droplet. Measurements infectivity change are coupled with detailed physicochemical analysis virus. A decrease ∼10% starting was observable min, large proportion loss occurring within first after aerosolization. The initial rate found correlate physical transformation equilibrating droplet; salts crystallize at relative humidities (RHs) below 50%, leading near-instant 50 60% However, 90% RH, droplet remains homogenous aqueous, viral sustained beyond which it decays only 10% remaining infectious min. high RH consistent elevation pH droplets, caused by volatilization CO from bicarbonate buffer droplet. Four different variants were compared have similar degree both low RH.