WHO Issues Updated Brief on Transmission of SARS-CoV-2

Jul 13, 2020 | COVID-19

On July 9, 2020, the World Health Organization (WHO) issued an updated brief on transmission of SARS-CoV-2. The brief is an update of a scientific brief published in March 2020, entitled “Modes of transmission of virus causing COVID-19: implications for infection prevention and control precaution recommendations,” and includes new scientific evidence available on transmission of SARS-CoV-2, the virus that causes COVID-19.

Key points of the brief include the following:

  • Current evidence suggests that transmission of SARS-CoV-2 occurs primarily between people through direct, indirect, or close contact with infected people through infected secretions such as saliva and respiratory secretions, or through their respiratory droplets, which are expelled when an infected person coughs, sneezes, talks or sings.

  • Airborne transmission of the virus can occur in health care settings where specific medical procedures, called aerosol generating procedures, generate very small droplets called aerosols. Some outbreak reports related to indoor crowded spaces have suggested the possibility of aerosol transmission, combined with droplet transmission, for example, during choir practice, in restaurants or in fitness classes.

  • Respiratory droplets from infected individuals can also land on objects, creating fomites (contaminated surfaces). As environmental contamination has been documented by many reports, it is likely that people can also be infected by touching these surfaces and touching their eyes, nose or mouth before cleaning their hands.

  • Based on what we currently know, transmission of COVID-19 is primarily occurring from people when they have symptoms, and can also occur just before they develop symptoms, when they are in close proximity to others for prolonged periods of time. While someone who never develops symptoms can also pass the virus to others, it is still not clear to what extent this occurs and more research is needed in this area.

To prevent transmission, WHO recommends the following:

  • Identify suspect cases as quickly as possible, test, and isolate all infected people in appropriate facilities.

  • Identify and quarantine all close contacts of infected people and test those who develop symptoms so that they can be isolated if they are infected and require care.

  • Use fabric masks in specific situations, for example, in public places where there is community transmission and where other prevention measures, such as physical distancing, are not possible.

  • Use of contact and droplet precautions by health workers caring for suspected and confirmed COVID-19 patients, and use of airborne precautions when aerosol generating procedures are performed.

  • Continuous use of a medical mask by health workers and caregivers working in all clinical areas, during all routine activities throughout the entire shift.

  • At all times, practice frequent hand hygiene, physical distancing from others when possible, and respiratory etiquette; avoid crowded places, close-contact settings and confined and enclosed spaces with poor ventilation; wear fabric masks when in closed, overcrowded spaces to protect others; and ensure good environmental ventilation in all closed settings and appropriate environmental cleaning and disinfection.

World Health Organization (WHO). Transmission of SARS-CoV-2: implications for infection prevention precautions [scientific brief]. July 9, 2020. Available at: click here. Accessed July 10, 2020.

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