Jul 9, 2020 - Health

WHO revises how COVID-19 can be transmitted

World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus

World Health Organization Director-General Tedros Adhanom Ghebreyesus. Photo: Fabrice Coffrini/POOL/AFP via Getty Images

The World Health Organization published an update on Thursday that states that airborne transmission of the novel coronavirus is possible, especially in poorly ventilated buildings.

Why it matters: Hundreds of scientists around the world have called on the WHO, which informs public health policy around the world, to acknowledge that particles containing the virus can float indoors and remain infectious, per the New York Times.

Where it stands: Knowledge about the symptoms and modes of transmission of SARS-CoV-2, the virus that causes COVID-19, is expanding. Here's what is known:

  • Airborne: COVID-19 has been known to possibly spread during medical procedures that generate aerosols. But WHO is exploring whether the aerosols may also have been responsible for outbreaks in closed settings "such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking, or singing.”
  • Droplets: WHO's update still maintains that the coronavirus is mainly transmitted through respiratory droplets directly or from being exposed to infected people via mouth and nose secretions. Some evidence suggests surfaces could indirectly infect others.
  • Asymptomatic spread: WHO confirms infected people can spread the virus when they don’t have symptoms. In June, WHO walked back comments that disregarded asymptomatic transmission, which caused public confusion.

Of note: WHO recently updated their face covering guidance to recommend that healthy people wear a mask in public and indoor settings when social distancing is not possible.

The bottom line: Several of these transmissions could happen at once, making it difficult for scientists to pinpoint the main mode of transmission. For example, people in choir practice, restaurants or fitness classes could be exposed to both aerosol and droplet transmission.

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