International health experts have agreed on a new definition of what it means for a disease to spread "through the air."
The agreement came after the World Health Organization (WHO) cooperated with hundreds of international health experts to explain or clarify the meaning. The WHO said the technical document it issued was the first step towards finding better methods to prevent airborne disease spread.
The document says the term "through the air" can be used for infectious diseases in which the main spread involves a pathogen traveling through the air or being suspended in the air. The experts said this is similar to the official description of "waterborne" diseases.
The WHO's new explanation is an effort to avoid public misunderstandings about how some diseases can be passed through the air or are "airborne."
Such misunderstandings happened during the COVID-19 pandemic. The WHO was criticized by many scientists during the early days of COVID-19 in 2020. They accused the U.N. health agency of failing to warn the public early on that the virus could spread through the air.
The scientists said this led to too much public guidance centered on handwashing and similar measures to prevent the spread of COVID-19. They said this guidance ignored other measures, such as looking at the spread of viruses through ventilation systems.
By July 2020, the agency said there was "evidence emerging" of airborne spread. Soumya Swaminathan was WHO chief scientist during the start of the COVID-19 pandemic. Swaminathan began a process to agree on a new definition for airborne disease spread. She later said she thinks the agency should have been more forceful in that message "much earlier."
Swaminathan's successor, Jeremy Farrar, recently told Reuters news agency the new definition was about more than COVID-19. He added that at the beginning of the pandemic there was a lack of available evidence. He said experts including the WHO had acted in "good faith." At the time, he headed the Wellcome Trust charity and advised the British government on COVID-19.
Farrar said the new definition would permit discussions to begin about issues such as ventilation in different kinds of buildings including hospitals and schools. He compared the issue to the realization that blood-borne viruses, like HIV or hepatitis B, could be spread by medics not wearing gloves.
"When I started out, medical students, nurses, doctors, none of us wore gloves to take blood," Farrar said. "Now it is unthinkable that you wouldn't wear gloves. But that came because everyone agreed on what the issue was, they agreed on the terminology... [The change, in practice,] came later," he added.
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