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 The Geneva-based World Health Organization acknowledged this week
that the novel coronavirus can spread through tiny droplets floating
in the air, a nod to more than 200 experts in aerosol science who
publicly complained that the U.N. agency had failed to warn the
public about this risk.
Yet the WHO still insists on more definitive proof that the novel
coronavirus, which causes the respiratory disease COVID-19, can be
transmitted through the air, a trait that would put it on par with
measles and tuberculosis and require even more stringent measures to
contain its spread.
"WHO's slow motion on this issue is unfortunately slowing the
control of the pandemic," said Jose Jimenez, a University of
Colorado chemist who signed the public letter urging the agency to
change its guidance.
Jimenez and other experts in aerosol transmission have said the WHO
is holding too dearly to the notion that germs are spread primarily
though contact with a contaminated person or object. That idea was a
foundation of modern medicine, and explicitly rejected the obsolete
miasma theory that originated in the Middle Ages postulating that
poisonous, foul-smelling vapors made up of decaying matter caused
diseases such as cholera and the Black Death.
"It's part of the culture of medicine from the early 20th century.
To accept something was airborne requires this very high level of
proof," said Dr. Donald Milton, a University of Maryland
aerobiologist and a lead author of the open letter.
Such proof could involve studies in which laboratory animals become
sickened by exposure to the virus in the air, or studies showing
viable virus particles in air samples - a level of proof not
required for other modes of transmission such as contact with
contaminated surfaces, the letter's signatories said.
For the WHO, such proof is necessary as it advises countries of
every income and resource level to take more drastic measures
against a pandemic that has killed more than 550,000 people
globally, with more than 12 million confirmed infections.
For example, hospitals would have to provide more healthcare
personnel with heavy-duty N95 respiratory masks - personal
protective gear already in short supply - and businesses and schools
would need to make improvements to ventilation systems and require
wearing masks indoors at all times.
"It would affect our entire way of life. And that's why it's a very
important question," said Dr. John Conly, a University of Calgary
infectious disease expert who is part of the WHO's group of experts
advising on coronavirus guidelines.
Conly said that so far the studies have not shown viable virus
particles floating in the air.
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"In my mind, I want to see evidence in those fine mists," Conly said.
HOW FAR CAN A DROPLET TRAVEL?
The WHO's latest guidance document, released on Thursday, called for more
research on coronavirus aerosol transmission, which it said "has not been
demonstrated."
The agency also repeated a firm cutoff on the size of infectious droplets
expelled in coughing and sneezing, noting that most larger droplets are unlikely
to travel beyond one meter (3.3 feet) - the basis for their one-meter social
distancing guidelines. Milton and others have said larger particles have been
shown to spread much farther.
Conly and others maintain that if the virus were truly airborne like measles,
there would already be many more cases.
"Would we not be seeing, like, literally billions of cases globally? That's not
the case," Conly said.
WHO spokeswoman Dr. Margaret Harris rejected the claim by critics that the
agency is biased against the idea of aerosol transmission, saying it recognized
the possibility of airborne transmission during medical procedures from early on
in the pandemic.
Harris said it is "quite possible" that aerosolization is a factor in some
so-called super-spreading events in which one infected person infects many
others in close quarters. Many of these events have occurred in places such as
nightclubs where people are packed together and are not likely to be careful
about protecting themselves or others from infection.
"Most super-spreading events have occurred in indoor places with poor
ventilation, with crowding, where it's very difficult for people to socially
distance," Harris said.
That is why, Harris said, the agency has called for urgent studies to figure out
"what really happened in these clusters and what were the big factors."
(This story is refiled to include dropped word "the" in paragraph 17)
(Reporting by Julie Steenhuysen; additional reporting by Stephanie Nebehey in
Geneva and Alistar Smout in London; Editing by Michele Gershberg, Will Dunham
and Sonya Hepinstall)
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