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Review
. 2020 Jul 6;9(1):100.
doi: 10.1186/s13756-020-00763-0.

Risk of SARS-CoV-2 transmission by aerosols, the rational use of masks, and protection of healthcare workers from COVID-19

Rami Sommerstein  1   2 , Christoph Andreas Fux  3 , Danielle Vuichard-Gysin  4   5 , Mohamed Abbas  6 , Jonas Marschall  7   4 , Carlo Balmelli  4   8 , Nicolas Troillet  4   9 , Stephan Harbarth  4   6 , Matthias Schlegel  4   10 , Andreas Widmer  4   11 ; Swissnoso
Collaborators, Affiliations
Review

Risk of SARS-CoV-2 transmission by aerosols, the rational use of masks, and protection of healthcare workers from COVID-19

Rami Sommerstein et al. Antimicrob Resist Infect Control. .

Abstract

Objectives: To determine the risk of SARS-CoV-2 transmission by aerosols, to provide evidence on the rational use of masks, and to discuss additional measures important for the protection of healthcare workers from COVID-19.

Methods: Literature review and expert opinion.

Short conclusion: SARS-CoV-2, the pathogen causing COVID-19, is considered to be transmitted via droplets rather than aerosols, but droplets with strong directional airflow support may spread further than 2 m. High rates of COVID-19 infections in healthcare-workers (HCWs) have been reported from several countries. Respirators such as filtering face piece (FFP) 2 masks were designed to protect HCWs, while surgical masks were originally intended to protect patients (e.g., during surgery). Nevertheless, high quality standard surgical masks (type II/IIR according to European Norm EN 14683) appear to be as effective as FFP2 masks in preventing droplet-associated viral infections of HCWs as reported from influenza or SARS. So far, no head-to-head trials with these masks have been published for COVID-19. Neither mask type completely prevents transmission, which may be due to inappropriate handling and alternative transmission pathways. Therefore, compliance with a bundle of infection control measures including thorough hand hygiene is key. During high-risk procedures, both droplets and aerosols may be produced, reason why respirators are indicated for these interventions.

Keywords: Aerosol; COVID-19; Droplet; Infection control; Mask; SARS-CoV-2; Transmission.

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Conflict of interest statement

None declared.

Figures

Fig. 1
Fig. 1
Multiphase Turbulent Gas Cloud from a Human Sneeze. Reprinted with written permission from JAMA [21]
Fig. 2
Fig. 2
Droplet transmission and high-risk procedures (potentially generating aerosol). Inner/outer semicircle indicate 2/8 m distance from the patients (center). Center-Right: A high-risk transmission procedure is depicted (“potentially aerosol generating procedure”), where a FFP2 mask is required. Center-Left: Uncontrolled coughing in hospital may cause a turbulent gas cloud to spread beyond 2 m [21]. Regular speech, even in asymptomatically infected patients may generate infectious droplets that travel 1-2 m. This is the rational of HCW to wear surgical masks in the hospital when caring for patients
See this image and copyright information in PMC

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