COVID-19 research briefs: a damp washcloth may reduce the number of aerosolized droplets generated by speech

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Published: 2020-05-07 © 2020 John Wiley & Sons, Inc.

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Clinical question
Can speaking through a damp washcloth reduce the number of the aerosolized droplets that have been implicated in the transmission of the COVID-19 virus?

Bottom line
Speaking through a damp washcloth resulted in a reduction of the droplets generated by speech. These droplets have been implicated as a possible source of transmitting the COVID-19 virus. It is unclear, however, whether the use of a damp washcloth could reduce the viral transmission of COVID-19. (LOE = 5)

Anfinrud P, Stadnytskyi V, Bax CE, Bax A. Visualizing speech-generated oral fluid droplets with laser light scattering. [published online ahead of print, 2020 Apr 15] N Engl J Med 2020;10.1056/NEJMc2007800. doi:10.1056/NEJMc2007800.

Study design: Other

Setting: Population-based

Research Brief #12: Aerosolized droplets generated during speech have been implicated as a possible source of transmitting COVID-19. In this in vitro experiment, researchers used fancy laser gadgets to determine how far respiratory droplets travel during speech, the sizes of the droplets, and the effect of speaking through a slightly damp washcloth (not sure why they didn't try out a homemade mask as a better test for the real world). They repeated the phrase - Stay healthy - at different volumes and found that the droplets traveled between 5 cm to 7.5 cm and ranged in size from 20 micrometers to 500 micrometers. As you might expect, the louder speech resulted in droplets that traveled farther. Using the damp washcloth resulted in dramatic reductions in the number and size of droplets, as well as the distance the droplets traveled. The authors are clear to report they did not assess viral transmission.

Henry C. Barry, MD, MS
Michigan State University
East Lansing, MI

Copyright © 2020 John Wiley & Sons, Inc.