Mean time to infection by small diffusing droplets containing SARS-CoV-2 during close social contacts

U. Dobramysl; C. Sieben; D. Holcman; U. Dobramysl; C. Sieben; D. Holcman

doi:10.3934/nhm.2024017

Networks and Heterogeneous Media

2024, Volume 19, Issue 1: 384-404. doi: 10.3934/nhm.2024017

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Mean time to infection by small diffusing droplets containing SARS-CoV-2 during close social contacts

1.
Peter Medawar Building for Pathogen Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK
2.
Nanoscale Infection Biology Group, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
3.
Group of data modeling and computational biology, IBENS-PSL Ecole Normale Superieure, Paris, France

Received: 16 May 2023 Revised: 18 December 2023 Accepted: 29 December 2023 Published: 04 April 2024

Airborne viruses such as SARS-CoV-2 are partly spread through aerosols containing viral particles. Inhalation of infectious airborne particles can lead to infection, a route that can be even more predominant than droplet or contact transmission. To study the transmission between a susceptible and an infected person, we estimated the distribution of arrival times of small diffusing aerosol particles to the inhaled region located below the nose until the number of particles reaches a critical threshold. Our results suggested that although contamination by continuous respiration can take approximately 90 min at a distance of 0.5 m, it is reduced to a few minutes when coughing or sneezing. Interestingly, there is not much difference between outdoors and indoors when the air is still. When a window is open inside an office, the infection time is reduced. Finally, wearing a mask leads to a delay in the time to infection. To conclude, diffusion analysis provides several key timescales of viral airborne transmission.
- aerosol diffusion,
- mean time to infection,
- simulations,
- modeling,
- SARS-CoV-2
Citation: U. Dobramysl, C. Sieben, D. Holcman. Mean time to infection by small diffusing droplets containing SARS-CoV-2 during close social contacts[J]. Networks and Heterogeneous Media, 2024, 19(1): 384-404. doi: 10.3934/nhm.2024017

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Abstract

Airborne viruses such as SARS-CoV-2 are partly spread through aerosols containing viral particles. Inhalation of infectious airborne particles can lead to infection, a route that can be even more predominant than droplet or contact transmission. To study the transmission between a susceptible and an infected person, we estimated the distribution of arrival times of small diffusing aerosol particles to the inhaled region located below the nose until the number of particles reaches a critical threshold. Our results suggested that although contamination by continuous respiration can take approximately 90 min at a distance of 0.5 m, it is reduced to a few minutes when coughing or sneezing. Interestingly, there is not much difference between outdoors and indoors when the air is still. When a window is open inside an office, the infection time is reduced. Finally, wearing a mask leads to a delay in the time to infection. To conclude, diffusion analysis provides several key timescales of viral airborne transmission.

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