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

Antimicrob Resist Infect Control. 2020 Jul 6;9(1):100. doi: 10.1186/s13756-020-00763-0.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Aerosols / analysis*
  • Air Microbiology
  • Betacoronavirus / physiology*
  • COVID-19
  • Coronavirus Infections / prevention & control*
  • Coronavirus Infections / transmission*
  • Coronavirus Infections / virology
  • Health Personnel
  • Humans
  • Infectious Disease Transmission, Patient-to-Professional / prevention & control
  • Pandemics / prevention & control*
  • Pneumonia, Viral / prevention & control*
  • Pneumonia, Viral / transmission*
  • Pneumonia, Viral / virology
  • Protective Devices
  • SARS-CoV-2


  • Aerosols