Does Expert Opinion Trump Evidence?

To the Editor—I read with great interest the Commentary by Morawska and Milton [1] published in the most recent edition of Clinical Infectious Diseases. Research to improve our understanding of how this virus transmits is pivotal and is clearly of the highest priority for public health worldwide, and Morawska and Milton have the solid background to study this issue.

My concern after reading the commentary is that the referencing associated with the crux of the letter is misleading:

Viral RNA associated with droplets smaller than 5 μm has been detected in air [14], and the virus has been shown​ to maintain infectivity in droplets of this size [9].

The first half of the sentence sets up that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was found in “aerosol-sized distributions,” and then goes on to state that the aerosolized virus is infectious. Reference 9 in the commentary refers to a paper by Cai et al [2] that examined a cluster of coronavirus disease 2019 (COVID-19) cases in a shopping mall in Wenzhou, China. They postulated that routes of transmission include fomites, aerosols, and/or asymptomatic carriers, but did not provide any laboratory confirmation that aerosolized SARS-CoV-2 is infectious.

My understanding from the literature is that there is no current evidence for infectivity of SARS-CoV-2 aerosols in nonexperimental, real-life settings. If there is evidence that I am not aware of, the reference for the letter’s powerful statement should be updated as such. If there is no evidence to back up the statement, I believe it should be removed or left unreferenced as conjecture. Due to the political nature of this commentary, it is crucial for any statements to be watertight. In its current form, it is misleading, particularly for people—including policymakers—that are not well versed in reading scientific literature and would not scrutinize references. Examples of how the letter “by Morawska and Milton [1]” has already been misleading, as confirmed by articles written by science commentators. In a New York Times article (239 Experts With One Big Claim: The Coronavirus Is Airborne), the author misinterprets the letter by stating “in an open letter to the WHO [World Health Organization], 239 scientists in 32 countries have outlined the evidence showing that smaller particles can infect people [3].” The second, in the Financial Times(An airborne virus is a threat worth taking seriously) published 14 July 2020, states, “last week, more than 200 specialists penned an open letter to the World Health Organisation urging it to officially accept that the COVID-19 virus can spread through the air further than social distancing recommendations [4].” Both articles accept that the current data is weak but misinterpret the letter by inferring there is a confirmed link with airborne spread and SARS-CoV-2 infection.

Whether SARS-CoV-2 is truly spread via the airborne route is still an unresolved issue [5], and although Morawska and Milton may well eventually be correct, it is of critical importance that expert statements that have far-reaching consequences for our health-care systems, public health, and the population at large are based on solid scientific evidence.

Note

Potential conflicts of interest. The author: No reported conflicts of interest. The author has submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest.