GENEVA - The World Health Organization on
Tuesday acknowledged "evidence emerging" of the airborne spread
of the novel coronavirus, after a group of scientists urged the
global body to update its guidance on how the respiratory
disease passes between people.
"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.
The WHO has previously said the virus that causes the
Covid-19 respiratory disease spreads primarily through small
droplets expelled from the nose and mouth of an infected person
that quickly sink to the ground.
But in an open letter to the Geneva-based agency, published
on Monday in the Clinical Infectious Diseases journal, 239
scientists in 32 countries outlined evidence that they say shows
floating virus particles can infect people who breathe them in.
Because those smaller exhaled particles can linger in the
air, the scientists in the group had been urging WHO to update
its guidance.
"We wanted them to acknowledge the evidence," said Jose
Jimenez, a chemist at the University of Colorado who signed the
paper.
"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 in a telephone interview.
Speaking at Tuesday's briefing in Geneva, Benedetta
Allegranzi, the WHO's technical lead for infection prevention
and control, 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."
Jimenez said historically, there has been a fierce
opposition in the medical profession to the notion of aerosol
transmission, and the bar for proof has been set very high. A
key concern has been a fear of panic.
"If people hear airborne, healthcare workers will refuse to
go to the hospital," he said.
Or people will buy up all the
highly protective N95 respirator masks, "and there will be none
left for developing countries."
Jimenez said the WHO panel assessing the evidence on
airborne transmission was not scientifically diverse, and lacked
representation from experts in aerosol transmission.
Any change in the WHO's assessment of risk of transmission
could affect its current advice on keeping 1-metre (3.3 feet) of
physical distancing. Governments, which rely on the agency for
guidance policy, may also have to adjust public health measures
aimed at curbing the spread of the virus.
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."