Could SARS-CoV-2 be transmitted via speech droplets?

Philip Anfinrud; Christina E Bax; Valentyn Stadnytskyi; Adriaan Bax

pathways but propose that their aggregate is key as oral fluid viral loads are already approaching peak levels by the time the patient presents, 8 and asymptomatic transmission is common. Further studies are needed to assess the viral titer present in speech-induced droplets in asymptomatic but COVID-19 positive persons, but our results suggest that speaking can indeed be a major mode of SARS-CoV-2 transmission. Our preliminary findings therefore have vital implications for pandemic mitigation efforts: If speaking and oral fluid viral load proves to be a major mechanism of SARS-CoV-2 transmission, wearing any kind of cloth mouth cover in public by every person, as well as strict adherence to social distancing and handwashing, could significantly decrease the transmission rate and thereby contain the pandemic until a vaccine becomes available. Fig. 1 . Visualizing droplet emission when speaking 'Stay Healthy three times.' (A) Number of droplets detected in each frame of a video acquired at a 60-Hz frame rate with and without a damp cloth face mask. Green indicates when the words were spoken. The trace offset below the major graph shows the absence of droplets during speech with mask coverage. (B) Frame # 361 from the video clip, which corresponds to the peak in the number of speech droplets detected; see red arrow in (A). The spots vary in brightness due to differences in size. The particle count after each repeated phrase remains above the background observed prior to the first repeat, suggesting that some of the speech droplets become aerosolized and linger inside the box for multiple seconds. Full video recordings are included as SI. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available author/funder, who has granted medRxiv a license to display the preprint in perpetuity.