SARS-CoV-2 Aerosol Transmission Indoors: A Closer Look at Viral Load, Infectivity, the Effectiveness of Preventive Measures and a Simple Approach for Practical Recommendations

Martin Kriegel, Anne Hartmann, Udo Buchholz, Janna Seifried, Sigrid Baumgarte and Petra Gastmeier
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Martin Kriegel: Hermann-Rietschel-Institut, Technical University of Berlin, 10623 Berlin, Germany
Anne Hartmann: Hermann-Rietschel-Institut, Technical University of Berlin, 10623 Berlin, Germany
Udo Buchholz: Department for Infectious Disease Epidemiology, Robert Koch Institute, 13353 Berlin, Germany
Janna Seifried: Department for Infectious Disease Epidemiology, Robert Koch Institute, 13353 Berlin, Germany
Sigrid Baumgarte: Local Health Authority “Hamburg-Nord”, 20249 Hamburg, Germany
Petra Gastmeier: Institute for Hygiene and Environmental Medicine, Charité-University Medicine Berlin, 12203 Berlin, Germany

IJERPH, 2021, vol. 19, issue 1, 1-31

Abstract: There is uncertainty about the viral loads of infectious individuals required to transmit COVID-19 via aerosol. In addition, there is a lack of both quantification of the influencing parameters on airborne transmission and simple-to-use models for assessing the risk of infection in practice, which furthermore quantify the influence of non-medical preventive measures. In this study, a dose–response model was adopted to analyze 25 documented outbreaks at infection rates of 4–100%. We show that infection was only possible if the viral load was higher than 10 8 viral copies/mL. Based on mathematical simplifications of our approach to predict the probable situational attack rate (PARs) of a group of persons in a room, and valid assumptions, we provide simplified equations to calculate, among others, the maximum possible number of persons and the person-related virus-free air supply flow necessary to keep the number of newly infected persons to less than one. A comparison of different preventive measures revealed that testing contributes the most to the joint protective effect, besides wearing masks and increasing ventilation. In addition, we conclude that absolute volume flow rate or person-related volume flow rate are more intuitive parameters for evaluating ventilation for infection prevention than air exchange rate.

Keywords: airborne transmission; infection prevention; risk assessment model; simplified approaches; SARS-CoV-2 (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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