Science-Blind: Opinions based on research vs personal

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  • #26
.Scott
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So in fact it was only 1 patient (not 2) then from whose room air they managed to get viable virus.
The paper describes two patients - and shows two patients in the diagram.
 
  • #27
atyy
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The paper describes two patients - and shows two patients in the diagram.
But from how many rooms did they manage to cultivate virus from sampling the air? One, or two?
 
  • #28
.Scott
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But from how many rooms did they manage to cultivate virus from sampling the air? One, or two?
It was one room (with a divider), two patients, two collectors.
There was one collector and one patient on either side of the room divider.
Apparently, the divider was not entirely effective at blocking the virus, because patient 2's collector was still picking up SARS-Cov-2 (at 16 particles per liter) after patient 2 was discharged.
 
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  • #29
atyy
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It was one room (with a divider), two patients, two collectors.
There was one collector and one patient on either side of the room divider.
Apparently, the divider was not entirely effective at blocking the virus, because patient 2's collector was still picking up SARS-Cov-2 (at 16 particles per liter) after patient 2 was discharged.
It looks to me like they did not get any live virus from Patient 2, who was negative. The live virus was from Patient 1, the active case.

I don't see them say anywhere that Patient 1 was not coughing during the collection.

Also, I don't see them exclude that Patient 1 got up and walked near the collecting device during the collection.

Is the bathroom shared between Patient 1 and Patient 2?
 
  • #30
Dr. Courtney
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It's easy to say that a mask meeting some standard helps if "all other factors are equal."

But that ignores the reality of human behavior. Most of the folks I've seen with masks are touching their faces every few minutes.

Some ground may be gained by masks regarding transmission via air. But how much ground is lost through contact transmission?

Me? I like distance. I like hand washing. I like not touching common objects. Do those things, and I don't think a mask helps. Don't do those things? I don't think a mask will make much difference.

But none of the mask mandates I've seen for public use even meet any given standard. I could wear any bit of cloth over my face, and so could anyone else.

So my household is putting more stock in reducing face-to-face social interactions by over 90% and keeping 6 feet away when we do go out.
 
  • #31
PAllen
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On the other hand, I am highly skeptical of surface transmission. Someone sneezes near a surface and it gets contaminated. Virus starts degrading at a steady rate. Someone touches the surface getting, say, 1/10 the viral load in the air near the surface at the time of the sneeze. Then, they scratch the outside of their nose, inhaling at the same time, say another tenfold reduction in viral load. Thus, compared to inhalation of aerosols near where someone recently sneezed, you have 100 fold reduction in viral load for the multistep touch transmission. Note, no amount of viral load on your hands will matter unless you touch your nose or mouth (possibly, but unverified, eyes) before washing your hands or waiting for the virus to degrade. Epidemiologists have so far documented no case whatsoever of coronovirus transmission primarily by surface touching. And of spread by droplet/aerosol inhalation, indoor cases outnumber outdoors by 50-1.

In my view, the best evidence supports the following:

1) indoors, the most critical thing is near universal mask wearing because aerosols can last an hour or more and distance is minimal protection. Evidence: detailed analysis of restaurant transmission, where adjacent tables as well as tables 20+ feet away connected by air flow patterns were the ones affected. Distance is the next most important factor. Mask wearing has to be near universal because the weaknesses of non ND95 masks are minimized if all parties wear them (at least covering nose and mouth).*

2) Outdoors, mask wearing is largely irrelevant unless people are a few feet or less from each other for many minutes, or (equivalently) there are a very large number of close contacts in a relatively short span of time.

Inhalation of droplets or aerosols is the only confirmed mode of transmission.

* Let's think about some basic physics of a mask that at least reasonably covers nose and mouth, but is not high tech. On inhale, negative pressure seals the edges reasonably well, on exhale (or sneeze) they open. With both wearing masks, these effects compensate to reduce viral load inhaled. Note, I have verified by my own experiments with chilled slides that all masks other than professionally fitted ND95 leak significantly on the edges on exhale, putting a lie to the oft quoted claim that they protect others more than you. However, epidemiologists are now more and more agreeing with the idea that for indoors protection when others are not wearing masks, the only adequate protection is an ND95 mask, irrespective of distance; and that otherwise, best bet for indoors is universal mask wearing as long as coverage is from bridge of nose to below chin (and distance doesn't much matter indoors, because of how far aerosols can travel before they dissipate).
 
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  • #32
atyy
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1) indoors, the most critical thing is near universal mask wearing because aerosols can last an hour or more and distance is minimal protection. Evidence: detailed analysis of restaurant transmission, where adjacent tables as well as tables 20+ feet away connected by air flow patterns were the ones affected. Distance is the next most important factor. Mask wearing has to be near universal because the weaknesses of non ND95 masks are minimized if all parties wear them (at least covering nose and mouth).*
That's the only case so far - is it a special case? Restaurants have opened in Singapore with safe distancing for quite some time now, with so far no rise in the rate of infections. People are unmasked while eating.

Incidentally, the authors of the report about the restaurant transmission case are cautious about inferring aerosol transmission. I do agree this one case is the strongest evidence to date for the possibility of aerosol transmission.

https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article
"Virus transmission in this outbreak cannot be explained by droplet transmission alone. Larger respiratory droplets (>5 μm) remain in the air for only a short time and travel only short distances, generally <1 m (2,3). The distances between patient A1 and persons at other tables, especially those at table C, were all >1 m. However, strong airflow from the air conditioner could have propagated droplets from table C to table A, then to table B, and then back to table C (Figure).

Virus-laden small (<5 μm) aerosolized droplets can remain in the air and travel long distances, >1 m (4). Potential aerosol transmission of severe acute respiratory syndrome and Middle East respiratory syndrome viruses has been reported (5,6). However, none of the staff or other diners in restaurant X were infected. Moreover, the smear samples from the air conditioner were all nucleotide negative. This finding is less consistent with aerosol transmission. However, aerosols would tend to follow the airflow, and the lower concentrations of aerosols at greater distances might have been insufficient to cause infection in other parts of the restaurant."
 
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  • #33
atyy
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On the other hand, I am highly skeptical of surface transmission. Someone sneezes near a surface and it gets contaminated. Virus starts degrading at a steady rate. Someone touches the surface getting, say, 1/10 the viral load in the air near the surface at the time of the sneeze. Then, they scratch the outside of their nose, inhaling at the same time, say another tenfold reduction in viral load. Thus, compared to inhalation of aerosols near where someone recently sneezed, you have 100 fold reduction in viral load for the multistep touch transmission. Note, no amount of viral load on your hands will matter unless you touch your nose or mouth (possibly, but unverified, eyes) before washing your hands or waiting for the virus to degrade. Epidemiologists have so far documented no case whatsoever of coronovirus transmission primarily by surface touching. And of spread by droplet/aerosol inhalation, indoor cases outnumber outdoors by 50-1.
I tend to agree. But there is one bizarre case that is hard to explain. Two people attended the same church at totally different times (when I've heard the data presented in a seminar, it seems that security camera footage supports that the two people did not meet), but sat in the same seat. It has been suggested that the first person infected the second. Look at the description of "Cluster A" in https://www.cdc.gov/mmwr/volumes/69/wr/mm6914e1.htm.
 
  • #34
atyy
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However, epidemiologists are now more and more agreeing with the idea that for indoors protection when others are not wearing masks, the only adequate protection is an ND95 mask, irrespective of distance
This paper supports that the restaurant case you mentioned was likely due to aerosol transmission. However, it does not support what you say about "irrespective of distance".

https://www.medrxiv.org/content/10.1101/2020.04.16.20067728v1
"However, the formation of a contaminated recirculation envelope in the ABC zone cannot alone explain the outbreak. Further evidence comes from the low ventilation rates: the observed high concentrations of the simulated contamination result from the lack of outdoor air supply. The exhaust fans in the walls were found to be turned off and sealed during the January 24 lunch ... The measured average air flows of 1.04 L/s and 0.75 L/s per patron in the non-ABC and ABC zones, respectively, are considerably lower than the 8–10 L/s per person required by most authorities or professional societies"

"It is important to note that our results do not show that long-range aerosol transmission of SARS-CoV-2 can occur in any indoor space, but that transmission may occur in a crowded and poorly ventilated space."

"The average room concentration of aerosols is thus a function of source strength and ventilation rate. When the ventilation rate of the room is sufficiently low, the room average condition can become as concentrated as within the exhaled air. Hence, in theory, even if an infectious agent is not typically (i.e., under adequate ventilation) transmitted by a long-range aerosol mechanism, the spatial extent of transmission increases if the ventilation rate is very low. We refer to such transmission as an extended short-range aerosol mechanism."
 
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  • #35
.Scott
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I tend to agree. But there is one bizarre case that is hard to explain. Two people attended the same church at totally different times (when I've heard the data presented in a seminar, it seems that security camera footage supports that the two people did not meet), but sat in the same seat. It has been suggested that the first person infected the second. Look at the description of "Cluster A" in https://www.cdc.gov/mmwr/volumes/69/wr/mm6914e1.htm.
There is no reason that you need to be in the same room at the same time to become exposed to a SARS-Cov-2 aerosol. The particles are smaller than tobacco smoke and will remain in undisturbed air for hours. If there is pedestrian traffic, it will not settle out. The limiting factor becomes the survival of the virus in that environment - which is related to temperature, humidity, and sunlight.
 
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  • #36
Since the question contained a major false assumption both based on and by scientific studies I have read let me simply address that. Equating dropping out of High School early with ignorance is a dangerous assumption. Many of our finest minds never even attended High School much less College. As an aeronautical Engineer I have been in developmental meetings where we came out with a new plane on a sheet of paper done by men using slide rules with 2 of the 5 having multiple doctorates and one a Jr high school diploma and another a grade school dropout.

The jr high school graduate was head of engineering and was certified in 5 fields of engineering as well as being a Naval Aviator and Flight Officer.

There are books, you read them...teachers NOT required. Just ask Abe Lincoln, Ben Franklin, George Washington, the Wright Brothers (their father had a large library - high school only,)

One of the reasons many of these students, and for me, dropping out - initially in Kindergarten until my dad said I could cut one day a week to go to a library or museum and write a report to quell my dissatisfaction with school that I had eagerly anticipated for years as a font of knowledge, only to find out that the other children could neither read, write or even add or subtract much less do any other more advanced math,...and there was this nap thing and some sort of milk fetish.

I think the questioner will find that politics and science make strange bedfellows and are best segregated.

Another reason for these dropouts - read a 100 year science book, it was written by professors with advanced degrees. They firmly believed that everything in that book was proven using the scientific method. Look at one from 200 years ago now - same rationale. Now guess what scientists will be doing with our school books 100 and 200 years from now. That’s right, ”How could these people have been so ignorant?”

Remember, education takes many forms. We learn every day. That is the purpose of this Forum. What a shame if we stopped at high school or college and having a piece of paper and felt that was “educated.”
 
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  • #37
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Try:
Logic: The Right Use of Reason in the Inquiry After Truth by Isaac Watts
Written in 1724 as a primary school textbook and still in use by major universities
 
  • #38
KurtLudwig
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I remember 60 years ago, similar arguments were made about the "unknown" harms of smoking. It stands to reason that smoking your lungs for years cannot lead to a good outcome. However, a belief is not a double-blind experiment. The argument by the tobacco lobby was that there is no scientific proof or precise biological mechanism that smoking causes lung cancer or emphysema. Their strategy was to sow doubt. An example to disproof was that an 86-year old, who was smoking 3 packs of Camels a day for over 70 years, was doing well.
There were statistics to show a strong link between smoking and lung cancer, but most people's minds cannot be changed by statistics or logic. Most people's minds will be changed only after painful personal experiences: their father or brother died of lung cancer. As these individual experiences accumulated, the general public very slowly started to change their mind.
My grandson and his friends only laughed and joked around about wearing a mask. They were invincible! After they caught the Covid-19 virus from one of their friends and were sick for a week or two, they have changed their minds somewhat. They are still invincible.
 
  • #39
anorlunda
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IMO it is wrong to cast the mask issue as one of knowledge versus ignorance. It is primarily a matter of trust.

Just a few months ago, science said that the public should not wear masks. Plenty of evidence about masks preventing spread existed back then, mostly in Asian publications. It is rational to suspect that either science deliberately lied to the public about masks because there were not enough N95 masks to go around, or that western science succumbed to the not-invented-here syndrome. Either way, trust in science and scientists took a big hit.

Public reluctance to believe scientists can sometimes be attributed to bad behavior of the scientists rather than the ignorance of the public. If scientists just stuck to publishing their scientific results and were silent on public policy, they would have more respect. The more often scientists say "Hear me and obey, because I am a scientist." the worse the problem.
 
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  • #40
phinds
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I have a friend who is an anti-vaxxer. She's quite intelligent, but there's no amount of scientific evidence that will persuade her that vaccines work.
Contradiction in terms. I would argue that she is NOT "quite intelligent".
 
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  • #41
PAllen
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IMO it is wrong to cast the mask issue as one of knowledge versus ignorance. It is primarily a matter of trust.

Just a few months ago, science said that the public should not wear masks. Plenty of evidence about masks preventing spread existed back then, mostly in Asian publications. It is rational to suspect that either science deliberately lied to the public about masks because there were not enough N95 masks to go around, or that western science succumbed to the not-invented-here syndrome. Either way, trust in science and scientists took a big hit.

Public reluctance to believe scientists can sometimes be attributed to bad behavior of the scientists rather than the ignorance of the public. If scientists just stuck to publishing their scientific results and were silent on public policy, they would have more respect. The more often scientists say "Hear me and obey, because I am a scientist." the worse the problem.
Yes, the Western decision to claim masks weren't important because there was a shortage was one of the worst health policy decisions ever made. Even independent of evidence one could track down, especially regarding the similar SARS and MERS viruses, it was logically inconsistent to say that N95 masks were critical to protect healthcare workers, but masks were not important for the public. Claims were made that imperfect masks wouldn't help the wearer because they couldn't stop viral size particles, while they protected others because they could stop droplets. This is a logical absurdity - if you catch it most commonly by droplets, then the mask that reduces droplets from one direction reduces them from the other as well. Failure to stop virus size particles is wholly irrelevant. This led me, back at the beginning of March, to trust nothing except my own investigations and experiments; the CDC and WHO were quite obviously not presenting objective science.
 
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  • #42
atyy
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This led me, back at the beginning of March, to trust nothing except my own investigations and experiments; the CDC and WHO were quite obviously not presenting objective science.
No comment on the CDC whose advice I have not followed in detail. For the WHO, I would say the public messaging was badly explained to the point of being misleading (which does erode public trust), rather than incorrect (ie. it was based on objective science), as it is true that if there is a mask shortage, medical masks should be prioritized for health care workers and people with respiratory symptoms, while the general community should rely on other measures such as safe distancing (in January the WHO guidance was safe distancing from people with respiratory symptoms, in April the WHO guidance was updated to have safe distancing in the community; the April guidance also provided considerations for masking when safe distancing could not be maintained, eg. in public transport).
 
  • #43
.Scott
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I remember a couple of significant public statements.

The first was from the Chinese when they first described this in January. My reaction was that this was likely big trouble (although it has been a bit bigger than I expected). The Chinese were obviously having difficulty containing this virus - even though, since the SARS outbreak, they were as prepared as anyone and more willing than most to impose quarantine measures. Since they most certainly would have implemented effective measures against fomite transmission, I was quite certain that wasn't it (or at least not all of it). In the two months following that, I looked at what droplets could do. That transmission method also seemed to me too vulnerable to determined authoritarian government. In terms of "trust", I trust the Chinese government to act and speak in their own interest - so in that context, they are trustworthy.

The second were the statements from Trumps and Fauci about masks. It was very clear to me what they were saying. Initially, it was spare the N95 masks for the front line workers. Later it was, a homemade mask might be of some use. Then it was hmmm... those homemade masks do seem to make a difference. Especially at the start, it was filled with "weasel wording" as many public figures were going out of their way to avoid acknowledging that N95 masks could be useful for general use. They just wanted to deliver the message that you shouldn't try to buy any. In terms of trust, it was easy to see what Fauci was trying to do. In contrast, Trump will always find (and declare) facts that support his views and policies.

If you think that they are still holding back information to the public, I tend to agree. For example, you can find a list of a dozen materials that you might touch and how long SARS-Cov-2 will keep on each of those. But you will never find human skin included on those lists.
 
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