Can Talking Spread Viruses?

A new study came out on April 6 to find out if typical every day talking can spread viruses. The research has not been peer-reviewed, but their results add new information to what we know about how viruses spread.

How did they test for the spread of Covid-19 by talking?

Laser-light scattering is what they used to count the number of droplets that came out from a subject as they were talking.

1. The subject talked into a dust-free enclosure to remove other particle sources.
2. Then they passed a planar laser beam that made microscopic particles visible that will otherwise be invisible to the naked eye.
3. A video was made while the subject is talking.
4. Then they counted the particles in all the frames using computer software.
5. Then the subject wore a mask to see if the number of droplets will be any different.

Results

When the phrase, “Stay Healthy” was spoken three times by the subject, thousands of droplets were recorded.

1. During speech without a cloth mask, hundreds of droplets were detected.
2. After talking, the number of droplets lowered, but many are still present, suggesting that the virus particles became aerosolized and remain floating in the box.
3. In one frame (see below), the droplets were as high as 360.
4. A damp homemade cloth mask dramatically reduced the number of droplets.

An image from the study showing 360 droplets is below.

Here is an explanation of the images above from the report.

Visualizing droplet emission when speaking ‘Stay Healthy three times.’

(A) The 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 squiggly line below the graph above shows the absence of droplets during speech with wearing a mask.

(B) Frame # 361 is from the video clip. This image shows 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 links below show videos of droplets while talking. To see is to believe. Download and watch.

with_mask.mp4
without_mask.mp4

Can speech droplets carry viruses?

Yes. a report study has shown that droplets emitted by speaking can carry respiratory germs like the measles virus, influenza virus, and the TB bacteria. [3]

Take -Away Message

1. Talking even with a normal voice without a mask may spread viruses like the Covid-19 virus.
2. The droplets that come out of the mouth can contain viruses and land on any surface and stay infectious for several hours or days. Read: How Long Can the Covid-19 Virus Survive in Common Surfaces?
3. Some of the viruses get aerosolized and linger in the air. Those can be inhaled and transfer the virus to another.  Read: How Long does the Covid-19 Virus Float in the Air and Stay on Surface?
4. Social distancing, hand washing and wearing a mask can prevent the spread and acquisition of the Covid-19 virus.

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Don’t Get Sick!

Related Reads:

1. Why Scheduled Surgery Has to Wait in Covid-19

2. SARS-CoV-2 Contamination in the Hospital Setting

3. How Long Can the Covid-19 Virus Survive in Common Surfaces?

4. SARS-CoV-2 Contamination in the Hospital Setting

5. How Long does the Covid-19 Virus Float in the Air and Stay on Surface?

6. The 2019-nCoV Is still present from a patient after sickness

7. 5 Reasons why Covid-19 Spreads Fast

8. New Study Explains the Rapid Spread of Covid-19

9. The Secondary Attack Rate of Covid-19

10. 10 Reasons Why the Wuhan Coronavirus Pneumonia is a Nightmare

References:

1. Philip Anfinrud, Christina E Bax, Valentyn Stadnytskyi, Adriaan Bax. Could SARS-CoV-2 be transmitted via speech droplets? medRxiv 2020.04.02.20051177; doi: https://doi.org/10.1101/2020.04.02.20051177.
2. Wen JC, McCannel CA, Mochon AB, Garner OB. Bacterial dispersal associated with speech in the setting of intravitreous injections. Arch Ophthalmol 2011;129:1551-4.
3. Asadi S, Wexler AS, Cappa CD, Barreda S, Bouvier NM, Ristenpart WD. Aerosol emission and superemission during human speech increase with voice loudness. Sci Rep 2019;9:2348

Image Credit: Figure and videos from Could SARS-CoV-2 be transmitted via speech droplets?

The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The article dited is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license.

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