The World Health Organization is minimizing the chance that Covid-19 will spread through airborne transmission by staying airborne, a group of scientists said.
In an open letter to be published this week, 239 scientists from 32 countries call for greater recognition of the role of the Covid-19 airborne spread and the need for governments to implement control measures.
The WHO guideline states that the virus is transmitted mainly between people through respiratory droplets and contact.Aerosol transmission involves much smaller particles that can remain in the air for long periods of time and can be transmitted to others at distances greater than one meter.
Members of the WHO infection prevention committee have said that while aerosol transmission may play some role, there is overwhelming evidence that the main routes of transmission are through direct contact and respiratory drops expelled during coughing. , sneezing or speaking. They said that introducing new measures to protect against aerosol transmission was unfeasible and unlikely to make much difference in the spread of infection.
The letter to be published in the journal Clinical Infectious Diseases is written by Lidia Morawska of the Queensland University of Technology in Brisbane and Donald Milton of the University of Maryland, and has been endorsed by more than 200 scientists, including some who have participated in the elaboration of the advice of the WHO.
They say emerging evidence, even from settings like meat processing plants where there have been outbreaks, suggests that airborne transmission may be more important than WHO has recognized.
Linsey Marr, an expert on airborne virus transmission at Virginia Tech and co-signer of the letter, told the New York Times that the WHO had relied on hospital studies suggesting low levels of the virus in the air. This underestimated the risk, he said, because in most buildings, “the air exchange rate is usually much lower, allowing the virus to accumulate in the air.”
The WHO says that certain medical procedures, such as intubation, increase the risk of transmission of aerosols, but that outside this context the evidence is less clear. “This is an area of active research,” says the WHO.
Paul Hunter, a professor of medicine at the University of East Anglia and a member of the WHO infection prevention committee, said the WHO had struck the right balance in its advice.
“Aerosol transmission can happen, but it’s probably not that important in the grand scheme of things. It’s about drops, ”he said. Controlling airborne transmission is not going to do much to control the spread of Covid-19. It will impose unnecessary burdens, particularly in countries where they do not have enough trained personnel or resources. “
If airborne transmission were to be shown to be an important factor, some experts have suggested that wearing masks indoors may be useful, even in settings where social distancing is being applied; that stricter regulations for ventilation and air conditioning may be needed to minimize air recirculation; and that it may even be appropriate to install UV lights in some buildings to protect against potentially infectious particles.
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