July 08, 2020

WHO Says 'Evidence Emerging' of Airborne Transmission of Covid 19

The World Health Organization (WHO) has acknowledged that there is "evidence emerging" that the coronavirus that causes Covid 19 disease can be spread by tiny particles suspended in the air.

The airborne transmission could not be ruled out in crowded, closed or poorly ventilated settings, an official said.

If the evidence is confirmed, it may affect guidelines for indoor spaces.

The WHO has so far said that the virus that causes the Covid-19 respiratory disease is primarily transmitted through droplets only when people cough or sneeze.

But an open letter from more than 200 scientists had accused the WHO of underestimating the possibility of airborne transmission.

Covid 19 virus particle
The Covid-19 virus particles
"We wanted them to acknowledge the evidence," Jose Jimenez, a chemist at the University of Colorado who signed the paper, told the Reuters news agency.

"This is definitely not an attack on the WHO. It's a scientific debate, but we felt we needed to go public because they were refusing to hear the evidence after many conversations with them," he said.

WHO officials have cautioned the evidence is preliminary and requires further assessment.

Benedetta Allegranzi, the WHO's technical lead for infection prevention and control, said that evidence emerging of airborne transmission of the coronavirus in "crowded, closed, poorly ventilated settings that have been described, cannot be ruled out".

Is WHO shifting its position?

For months, the WHO has insisted that Covid-19 is transmitted via droplets emitted when people cough or sneeze. Droplets that do not linger in the air, but fall onto surfaces - that's why handwashing has been identified as a key prevention measure.

But 239 scientists from 32 countries don't agree: in an open letter to the WHO, published on Monday in the Clinical Infectious Diseases journal, they say there is strong evidence to suggest the virus can also spread in the air: through much tinier particles that float around for hours after people talk, or breathe out.

Because those smaller exhaled particles can linger in the air, the scientists are urging WHO to update its guidance.

Speaking at Tuesday's briefing in Geneva, Benedetta Allegranzi said there was evidence emerging of airborne transmission of the coronavirus, but that it was not definitive.

"...The possibility of airborne transmission in public settings - especially in very specific conditions, crowded, closed, poorly ventilated settings that have been described, cannot be ruled out," she said.

"However, the evidence needs to be gathered and interpreted, and we continue to support this."

"We have been talking about the possibility of airborne transmission and aerosol transmission as one of the modes of transmission of Covid-19," Maria Van Kerkhove, technical lead on the Covid-19 pandemic at the WHO, told a news briefing.

Van Kerkhove said the WHO would publish a scientific brief summarising the state of knowledge on modes of transmission of the virus in the coming days.

"A comprehensive package of interventions is required to be able to stop transmission," she said.

"This includes not only physical distancing, it includes the use of masks where appropriate in certain settings, specifically where you can't do physical distancing and especially for healthcare workers."

Since the WHO has now admitted there is evidence to suggest small exhaled particles lingering in the air was possible in specific settings, such as enclosed and crowded spaces, it might need to change its assessment of risk of transmission.

That evidence will have to be thoroughly evaluated, but if it is confirmed, the advice on how to prevent the virus spreading may have to change, and could lead to more widespread use of masks, and more rigorous physical distancing, especially in bars, restaurants, and on public transport.

Governments, which rely on the Geneva-based agency for guidance policy, may also have to adjust public health measures aimed at curbing the spread of the virus.

Source:
The above article is reproduced from material entitled 'WHO acknowledges 'evidence emerging' of airborne spread of COVID-19' as provided by Reuters. Note: Materials may be edited for content and length.

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