The potential for Covid-19 to spread through airborne transmission by lingering in the air is being underplayed by the World Health Organization (WHO), a group of scientists have said. In an open letter due to be published this week, 239 scientists from 32 countries call for greater acknowledgement of the role of airborne spread of Covid-19 and the need for governments to implement control measures.
WHO guidance states that the virus is transmitted primarily 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 over distances greater than one meter.
The letter due to be published in the journal Clinical Infectious Diseases…has been endorsed by more than 200 scientists, including some who have been involved in drawing up the WHO’s advice.
They say emerging evidence, including from settings such as meat processing plants where there have been outbreaks, suggests that airborne transmission could be more important than the WHO has acknowledged.
Linsey Marr, an expert in airborne transmission of viruses at Virginia Tech and a co-signatory of the letter, told the New York Times that the WHO had relied on studies from hospitals that suggested low levels of virus in the air. This underestimated the risk, she said, because in most buildings “the air-exchange rate is usually much lower, allowing virus to accumulate in the air.”