From the Journals

Ten reasons airborne transmission of SARS-CoV-2 appears airtight


Response to a review

The top 10 list is also part rebuttal of a systematic review funded by the WHO and published last month that points to inconclusive evidence for airborne transmission. The researchers involved with that review state that “the lack of recoverable viral culture samples of SARS-CoV-2 prevents firm conclusions to be drawn about airborne transmission.”

However, Dr. Greenhalgh and colleagues note that “this conclusion, and the wide circulation of the review’s findings, is concerning because of the public health implications.”

The current authors also argue that enough evidence already exists on airborne transmission. “Policy should change. We don’t need more research on this topic; we need different policy,” Dr. Greenhalgh said. “We need ventilation front and center, air filtration when necessary, and better-fitting masks worn whenever indoors.”

Dr. Allen agreed that guidance hasn’t always kept pace with the science. “With all of the new evidence accumulated on airborne transmission since last winter, there is still widespread confusion in the public about modes of transmission,” he said. Dr. Allen also serves as commissioner of The Lancet COVID-19 Commission and is chair of the commission’s Task Force on Safe Work, Safe Schools, and Safe Travel.

“It was only just last week that CDC pulled back on guidance on ‘deep cleaning’ and in its place correctly said that the risk from touching surfaces is low,” he added. “The science has been clear on this for over a year, but official guidance was only recently updated.”

As a result, many companies and organizations continued to focus on “hygiene theatre,” Dr. Allen said, “wasting resources on overcleaning surfaces. Unbelievably, many schools still close for an entire day each week for deep cleaning and some still quarantine library books. The message that shared air is the problem, not shared surfaces, is a message that still needs to be reinforced.”

The National Institute for Health Research, Economic and Social Research Council, and Wellcome support Dr. Greenhalgh’s research. Dr. Greenhalgh and Dr. Allen had no relevant financial relationships to disclose.

A version of this article first appeared on


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