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

Rami Sommerstein, Christoph Andreas Fux, Danielle Vuichard-Gysin, Mohamed Abbas, Jonas Marschall, Carlo Balmelli, Nicolas Troillet, Stephan Harbarth, Matthias Schlegel, Andreas Widmer, Carlo Balmelli, Marie Christine Eisenring, Stephan Harbarth, Didier Pittet, Hugo Sax, Matthias Schlegel, Alexander Schweiger, Laurence Senn, Nicolas Troillet, Andreas F. WidmerGiorgio Zanetti

Research output: Contribution to journalReview articlepeer-review

158 Scopus citations


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.

Original languageEnglish
Article number100
JournalAntimicrobial Resistance and Infection Control
Issue number1
StatePublished - Jul 6 2020


  • Aerosol
  • COVID-19
  • Droplet
  • Infection control
  • Mask
  • SARS-CoV-2
  • Transmission


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