Open AccessModelling airborne transmission of SARS-CoV-2 using CARA: risk assessment for enclosed spaces
Author(s) -
Andre Henriques,
Nicolas Mounet,
Luis Aleixo,
Philip Elson,
James D. Devine,
Gabriella Azzopardi,
Marco Andreini,
Markus Rognlien,
Nicola Tarocco,
Julian W. Tang
Publication year - 2022
Publication title -
interface focus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 49
eISSN - 2042-8901
pISSN - 2042-8898
DOI - 10.1098/rsfs.2021.0076
Subject(s) - airborne transmission , transmission (telecommunications) , covid-19 , risk assessment , pandemic , infection risk , environmental science , computer science , risk analysis (engineering) , outbreak , medicine , virology , intensive care medicine , infectious disease (medical specialty) , telecommunications , computer security , disease , pathology
The COVID-19 pandemic has highlighted the need for a proper risk assessment of respiratory pathogens in indoor settings. This paper documents the COVID Airborne Risk Assessment methodology, to assess the potential exposure of airborne SARS-CoV-2 viruses, with an emphasis on virological and immunological factors in the quantification of the risk. The model results from a multidisciplinary approach linking physical, mechanical and biological domains, enabling decision makers or facility managers to assess their indoor setting. The model was benchmarked against clinical data, as well as two real-life outbreaks, showing good agreement. A probability of infection is computed in several everyday-life settings and with various mitigation measures. The importance ofsuper-emitters in airborne transmission is confirmed: 20% of infected hosts can emit approximately two orders of magnitude more viral-containing particles. The use of masks provides a fivefold reduction in viral emissions. Natural ventilation strategies are very effective to decrease the concentration of virions, although periodic venting strategies are not ideal in certain settings. Although vaccination is an effective measure against hospitalization, their effectiveness against transmission is not optimal, hence non-pharmaceutical interventions (ventilation, masks) should be actively supported. We also propose a critical threshold to define an acceptable risk level.