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Tue Jun 30, 2020, 06:23 PM

Reducing transmission of SARS-CoV-2

This somewhat scary "perspective" is found in the current issue of Science: Reducing transmission of SARS-CoV-2 (Kimberly A. Prather1, Chia C. Wang2,3, Robert T. Schooley4 Science 26 Jun 2020: Vol. 368, Issue 6498, pp. 1422-1424)

I presume it's open sourced:

Some excerpts:

Respiratory infections occur through the transmission of virus-containing droplets (>5 to 10 m) and aerosols (≤5 m) exhaled from infected individuals during breathing, speaking, coughing, and sneezing. Traditional respiratory disease control measures are designed to reduce transmission by droplets produced in the sneezes and coughs of infected individuals. However, a large proportion of the spread of coronavirus disease 2019 (COVID-19) appears to be occurring through airborne transmission of aerosols produced by asymptomatic individuals during breathing and speaking (13). Aerosols can accumulate, remain infectious in indoor air for hours, and be easily inhaled deep into the lungs. For society to resume, measures designed to reduce aerosol transmission must be implemented, including universal masking and regular, widespread testing to identify and isolate infected asymptomatic individuals.

Humans produce respiratory droplets ranging from 0.1 to 1000 m. A competition between droplet size, inertia, gravity, and evaporation determines how far emitted droplets and aerosols will travel in air (4, 5)...

...it is possible that submicron virus-containing aerosols are being transferred deep into the alveolar region of the lungs, where immune responses seem to be temporarily bypassed. SARS-CoV-2 has been shown to replicate three times faster than SARS-CoV-1 and thus can rapidly spread to the pharynx, from which it can be shed before the innate immune response becomes activated and produces symptoms (6). By the time symptoms occur, the patient has transmitted the virus without knowing...

...The U.S. Centers for Disease Control and Prevention (CDC) recommendations for social distancing of 6 feet and hand washing to reduce the spread of SARS-CoV-2 are based on studies of respiratory droplets carried out in the 1930s. These studies showed that large, ∼100 m droplets produced in coughs and sneezes quickly underwent gravitational settling (1). However, when these studies were conducted, the technology did not exist for detecting submicron aerosols...

...Measurements now show that intense coughs and sneezes that propel larger droplets more than 20 feet can also create thousands of aerosols that can travel even further (1). Increasing evidence for SARS-CoV-2 suggests the 6 feet CDC recommendation is likely not enough under many indoor conditions, where aerosols can remain airborne for hours, accumulate over time, and follow airflows over distances further than 6 feet (5, 10)...


The article goes on to suggest an explanation of why Taiwan, despite having no lockdown, had a low infection rate, while the United States didn't.

Hint: Not that we wish to offend members of the Trump cult here at DU, it involves, um, masks. The article suggests that "social distancing" may not be enough.


A graphic:



The caption:

Masks reduce airborne transmission.

Infectious aerosol particles can be released during breathing and speaking by asymptomatic infected individuals. No masking maximizes exposure, whereas universal masking results in the least exposure.


It is important to note, and it's easy to forget this, that wearing a mask does not protect the wearer so much as it protects other people. This explains the Republican resistance to wearing them. They just don't give a shit about other people.

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Arrow 7 replies Author Time Post
Reply Reducing transmission of SARS-CoV-2 (Original post)
NNadir Jun 30 OP
AllaN01Bear Jun 30 #1
BigmanPigman Jun 30 #2
NNadir Jun 30 #3
Arsenalpe Jul 1 #4
NNadir Jul 1 #5
Boomer Jul 1 #6
NNadir Jul 1 #7

Response to NNadir (Original post)

Tue Jun 30, 2020, 06:36 PM

1. moral of this story, die , or wear a mask dang nabbit

how hard is that to do.

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Response to NNadir (Original post)

Tue Jun 30, 2020, 06:49 PM

2. Why aren't N95 masks being mass produced?

It has been months...how fucking long does it take to make good masks? Didn't the fucking moron sign a paper for war-time production of masks or is that sitting in the THINGS I DO NOT CARE ABOUT folder on his desk under the info about Putin's $$$ to Taliban?

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Response to BigmanPigman (Reply #2)

Tue Jun 30, 2020, 07:10 PM

3. As a veteran of the scale up of AIDS drugs in the 1990's...

...I can tell you that scale up is not quite like turning on the spigot.

Supply chains can be quite inflexible and problematic.

I had two N95's in my house, because my son was working with a sculptor. Going from the set of sculptors and construction workers to the entire planet is a big chore.

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Response to NNadir (Original post)

Wed Jul 1, 2020, 02:12 AM

4. Masks reduce the transmission

Hoo Noo! How dangerous we are in now? I don't know what to do now. I have one doubt. Masks can control the virus? Because the virus can live in clothes or paper etc. We carry that infected mask into our home only. We pick that mask in our hands only. Is it safe? I am happy about that thing i.e., to wear a mask to control the virus. Please give some advice about how to take care of masks or which type of masks are using better

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Response to Arsenalpe (Reply #4)

Wed Jul 1, 2020, 02:39 AM

5. I touched on this point, albeit in a somewhat technical way elsewhere in this space.

Steven Chu and Yi Cui: Can N95 Respirators Be Reused after Disinfection? How Many Times?

The lifetime of masks depends on the material with which they are made, as does treatment.

Some masks are cloth materials that can be washed. We know that surfactants, soaps, inactivate the virus. We also know that the lifetime of the virus on surfaces is not infinite.

I circulate my masks, keeping them in a hot car to minimize the stability of the virus. I have two N95's that my son had left over from his days as a sculpture intern. I've been switching them out each week.

Personally, when handling my masks after a long day, I gel my hands.

The bottom line however is that wearing a mask is an exercise in protecting - for the most part - other people. It offers some protection to one's self, but it is not 100% effective; it just improves your odds. If your mask is highly infected, it is probable that you are infected as well.

Recognizing this, I try to stay as far away from people who are not wearing a mask. They are more dangerous to you than your own mask.

I hope this helps.

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Response to Arsenalpe (Reply #4)

Wed Jul 1, 2020, 02:14 PM

6. A couple of points

You can't catch the coronavirus through the skin of your hands, so if you touch your mask AND THEN WASH YOUR HANDS, you should be fine. As long as you don't touch your face in between. So my routine when returning home is to wash my hands, take off my mask and store it away, and then wash my hands again.

And just a pedantic side note: what I've read is that soap has no effect on the virus itself, it just helps wash the virus away from your skin.

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Response to Boomer (Reply #6)

Wed Jul 1, 2020, 03:47 PM

7. Your last statement is not actually true.

The virus has a lipid layer that is essential to its ability to be infectious. Soap disrupts this layer.

This lipid envelop is critical to infection, since it allows fusion with the cell membrane:

2. Viral structure and life cycle
COVID-19 is a single, positive-stranded RNA virus enveloped in a lipid bilayer [6,7]. The lipid bilayer fuses with the host cell membrane, releasing RNA into the cytoplasm and causing translation of various viral proteins. The replicated RNA genome and synthesized viral proteins reassemble into new viruses, which burst out of the cell [8,9].



Epidemiology and clinical features of COVID-19: A review of current literature (Siordia, Journal of Clinical Virology Volume 127, June 2020, 104357)

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