Coronavirus airborne? Evidence 'not enough', says health dept

Henrietta Brewer
July 7, 2020

This means that poorly ventilated rooms, trains, and other confined spaces can be risky, even if people follow the commonly implemented one-meter social distancing rule.

They have asked the World Health Organisation (WHO) to revise their recommendation, the New York Times (NYT) reported on Saturday.

World Health Organization reportedly said it was considering aerosols as a possible route of transmission for the SARS-CoV-2, the virus that causes the Covid-19 disease, but is not yet convinced that the evidence necessitated a change in guidance. These include settings in which procedures that generate aerosols are performed; endotracheal intubation; bronchoscopy; open suctioning; administration of nebulised treatment; manual ventilation before intubation; turning a patient to the prone position; disconnecting a patient from the ventilator; non-invasive positive-pressure ventilation; tracheostomy; and cardiopulmonary resuscitation. But it turns out that the virus is more unsafe than it was imagined.

In the paper, the authors purport to demonstrate that airborne transmission is "highly virulent and represents the dominant route for the transmission of this disease". (Though a 2018 study actually found that the flu may sometimes be airborne - another illustration of why this distinction is so fuzzy.) Somewhere in the middle of this spectrum, you likely have covid-19, a disease that's mostly droplet-spread but can be airborne sometimes. The researchers intend to publish their letter in the journal Clinical Infectious Diseases shortly. "Our results indicate that aerosol and fomite transmission of SARS-CoV-2 is plausible since the virus can remain viable and infectious in aerosols for hours", the study said.

"Handwashing and social distancing are appropriate, but [are] insufficient to provide protection from virus-carrying respiratory microdroplets released into the air by infected people", she added. If the droplets particles are larger than 5-10 microns in diameter, they are referred to as respiratory droplets; if they are smaller than 5 microns in diameter, they are referred to as droplet nuclei. These droplets are expelled when a coronavirus infected person speaks, coughs or sneezes.

We don't know whether added measures, such as the widespread donning of N95 masks by health care workers and the public, would meaningfully help more than surgical and cloth masks. Many of us have claimed its relevance from very early in this pandemic.

Concerned scientists said that the World Health Organization is setting too stringent a standard of evidence, during a fast-moving pandemic, and needs to move forward with prevention techniques.

Those small particles can penetrate deeper into the lungs when inhaled, according to Meselson, "Aerosols from infected persons may therefore pose an inhalation threat even at considerable distances and in enclosed spaces, particularly if there is poor ventilation", he wrote in his letter to the editor. Instead, the goal of the appeal is for public health authorities to more broadly spread messaging to prevent the potential of airborne transmission. Ultraviolet lights may need to be used to kill viral particles.

Currently, the matter of the deadly virus being airborne is unclear.

"In many countries where air pollution is a major health hazard, even opening windows does have some consequences, and whilst it's generally easy to ventilate indoor spaces in clement weather, it's less practical (or costly both economically and environmentally) in extremes of heat and cold", says Javid.

Chief WHO scientist Soumya Swaminathan tells the Times her staff members are working tirelessly to evaluate new scientific evidence as fast as possible.

The key question is not whether airborne transmission is theoretically possible; it certainly is.

Other reports by iNewsToday