Medical Science, Medical Ethics, COVID-19

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.Scott
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Summary:

WHO is balking on pointing its finger at COVID-19 aerosol.
Medical science constrained by "Do no harm".

Main Question or Discussion Point

There is a COVID-19 issue that has been brewing for at least a couple of months: Is the primary COVID-19 communication vector aerosols?
But only in the past couple of weeks has this issue started to come to a boil - as in this article:
WHO Balks at Pointing to Aerosols

The difference here is aerosol vs. droplets; colloidal dispersion vs. mist.
Both are emitted when you sneeze, sing, or talk. But droplets drop to the floor in minutes.
A colloidal dispersion, in contrast, does not.
If you really hate cigarettes, then cigarette smoke makes for a good model. When talking with someone who is smoking, you would like to keep your distance - and six feet isn't too bad. But if you're indoors, it's not going to matter. The smoke will build up and within half an hour, it will be time to leave or suffer.
The COVID-19 virus is about 125 microns in diameter - perhaps double that if you include other matter hanging on to it. That would make it as bad as cigarette smoke in terms of persistence. It would hang in the air for hours (and long after the smoker had left) - but only if the air was still. Moving air could keep it airborne indefinitely.

So, in an indoor COVID-19 setting, the difference between aerosol and mist is hugely significant. If COVID-19 can be communicated by aerosol, then a whole new set of rules related to ventilation would need to be researched and developed and COVID-19 contagion models would need to be revised.

So, does COVID-19 efficiently communicate through aerosols?
1) The Skagit County Choir: This is a well-publicized event that took place in March. The CDC report is here (warning, slow link, be patient):
CDC Report on Skagit County "Super Spread" event.
They don't really provide a "synopsis", but under the heading "What is added by this report", they say:
Following a 2.5-hour choir practice attended by 61 persons, including a symptomatic index patient, 32 confirmed and 20 probable secondary COVID-19 cases occurred (attack rate = 53.3% to 86.7%); three patients were hospitalized, and two died. Transmission was likely facilitated by close proximity (within 6 feet) during practice and augmented by the act of singing.
This report cites the 6-foot rule several times and it mentions both droplets and aerosols. But the case against droplets is not as strong as this report suggests. For example:
First, the seating chart was not reported because of concerns about patient privacy. However, with attack rates of 53.3% and 86.7% among confirmed and all cases, respectively, and one hour of the practice occurring outside of the seating arrangement, the seating chart does not add substantive additional information.
This suggests that seating proximity to the index patient was not well-correlated to the contagion - at least not positively correlated.

2) What we exhale: This has been well-examined by Sima Asadi, et al - Asadi Study - What we exhale.
It has long been recognized that particles expelled during human expiratory events, such as sneezing, coughing, talking, and breathing, serve as vehicles for respiratory pathogen transmission. The relative contribution of each expiratory activity in transmitting infectious microorganisms, however, remains unclear. Much previous research has focused on coughing and sneezing activities that yield relatively large droplets (approximately 50 μm or larger) easily visible to the naked eye. Less noticeable, but arguably more infectious for some diseases, are the smaller particles emitted during sneezing and coughing as well as during breathing and talking. These small particles are believed to be generated during breathing and talking from the mucosal layers coating the respiratory tract via a combination of a “fluid-film burst” mechanism within the bronchioles and from vocal folds adduction and vibration within the larynx. The particles emitted during breathing and typical speech predominantly average only 1 μm in diameter and are thus too small to see without specialized equipment; most people outside of the community of bioaerosol researchers are less aware of them.
This article also suggests that aerosol particles may be more infectious that droplets.
One interesting phenomena explored in this study is the "super-emitter", people who emit an order of magnitude more particles than average. What I have not seen in any study is evidence of a super-emitter being tied to a super-spreader event. Quite the opposite: There is commonly a caveat saying that (in the context of disease-containment practicality) it is not possible to diagnose someone as a superspreader. My point is that I see no reason to conclude that superspreader events are most commonly "sponsored" by super-emitters.

So why is the WHO balking?
For the same reason I did not post this weeks ago. There is little more than (excuse the pun) a smoking gun.
From the NY Times (NYT Article on Open Letter to WHO):
Dr. Benedetta Allegranzi, the W.H.O.’s technical lead on infection control, said the evidence for the virus spreading by air was unconvincing.

“Especially in the last couple of months, we have been stating several times that we consider airborne transmission as possible but certainly not supported by solid or even clear evidence,” she said. “There is a strong debate on this.”
Which brings us directly to the issue of ethics. You can't actually recreate a super-spreader event in the lab. It would be unethical. As a doctor or a scientist, it is unethical to send people (even enthusiastic, well-informed volunteers) into harm's way for the greater good. But for elected executive office leaders, it is standard practice. Bear this in mind the next time you see your favorite national executive speaking in contrast to your favorite national medical advisor. They are speaking from separate roles.

Here is one more article which bears on how profound the difference would be between aerosol and droplets - although that is not the gist of the article:
MIT Superspreader Article June 15
What’s the impact of superspreaders for covid-19? Researchers are beginning to come to a consensus after several new studies showing that coronavirus transmission more or less follows the 80/20 Pareto Principle (named after Italian economist Vilfredo Pareto): 80% of all consequences come from just 20% of the possible causes. For covid-19, this means 80% of new transmissions are caused by fewer than 20% of the carriers—the vast majority of people infect very few others or none at all, and it’s a select minority of individuals who are aggressively spreading the virus. A recent preprint looking at transmission in Hong Kong supports those figures, while another looking at transmission in Shenzhen, China, pegs the numbers closer to 80/10.
What that article is really discussing is "super-spreader" events - not specifically super-spreaders.
But cutting the infection rate by a factor of 5 (an 80% reduction) would stop Covid-19 almost immediately.
 
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Answers and Replies

  • #2
.Scott
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The open letter to the WHO has now been published. A link to the PDF is at this URL:
Open Letter to WHO
 
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  • #3
phyzguy
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The COVID-19 virus is about 125 microns in diameter -
I think you mean that the COVID-19 virus itself is about 125 nanometers in diameter. 1000 times smaller in diameter and 1 billion times smaller in volume than what you said.
 
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"As a doctor or a scientist, it is unethical to send people (even enthusiastic, well-informed volunteers) into harm's way for the greater good. "

So was it unethical to send me to Vietnam for two years or send someone to a more popular war? I like many vets would gladly give my life for the greater good in the "war" with Covid-19.

More than one hundred thirty thousand of our countrymen have died. How could it be considered unethical for a few more "well-informed volunteers" to fight this battle?

As I look out my window on the 4th of July and see 40 people having a party in Miami Florida, getting drunk and no mask to be seen I wonder if I have lost my mind wanting to protect you. I am compelled to try....even when you have no regard for your own safety or any one else.

Best regards,

Billy
 
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gleem
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Evidence is being found that Covid infections are producing long term damage to various organs (lung, liver, kidney, heart, and brain). Also, there is some concern that there may not be a permanent immunity. Will this mean that the reinfection of the population will result in a larger mortality rate compared to the initial infection? If the virus retains its basic characteristics (organ damage) and mutates periodically like the flu could this lead to a higher mortality rate if we do not very aggressively protect ourselves? It really sounds like you do not want to get this a second time.

Do those with no, minimal symptoms or not requiring hospitalization suffer significant but unrecognized organ damage? Should recovered people have routine diagnostic tests to assess the possibly affected organ damage? What about the possibility of latent effects? This virus seems to be doing things that its relatives do not.

This virus has left a lot to be investigated.
 
  • #6
phyzguy
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I hear lots of concern that there may be limited immunity, but I have heard no reports of anyone getting it twice. Is anyone aware of any cases where someone has gotten it twice? The first major cases were in January/February. If the immunity were really short term, there should already be people being re-infected.
 
  • #7
Vanadium 50
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t I have heard no reports of anyone getting it twice. Is anyone aware of any cases where someone has gotten it twice?
We have a forum member who says he got it three times.
 
  • #8
jim mcnamara
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FWIW- I cannot find any clinical case studies that show covid reinfection -- using google scholar. Which proves nothing of course. Except maybe that no physician has reported it if it does occur.

There are many case studies of covid with secondary and post-infection serious problems. This pathlogical nastiness is also reported with measles, MERS, chicken pox, etc.

It is possible that our above example reinfection is really prolonged disease process. Or maybe something more psychological.
 
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  • #9
jim mcnamara
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Referencing above post about reinfection leads to duration of immunity.

Screenshot_2020-07-11 Coronavirus Pandemic Update 93 Antibodies, Immunity, Prevalence of COVID...png



Which finds 40% of asymptomatic patients who were seropositive , when tested later (IgG) were found to be seronegative. So this appears to imply the possibility of asymptomatic patients as sources for reinfection.

It may also suggest that there is a possibility of limited persisting resistance from vaccination.
 
  • #10
gleem
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If a person has a reoccurrence of symptoms is that a result of a reinfection or a relapse from the initial infection.
This is just one article but some scientists believe that even after symptoms disappear a relapse could occur for COVID. My OP presupposed a somewhat longer immune period such that a second wave might be that which poses a risk to those who have lost their immunity. I would suppose a relapse has a shorter time for symptom reoccurrence compared to if there is a temporary immunity.
 
  • #11
Laroxe
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I'm actually a bit surprised that the idea of aerosol spread caused so much discussion its basically a debate about droplet size which in nature have no clear cut off point and people generate the full range of sizes all the time. Singing and talking loudly seem to be a particular problem, which is why bars are considered such a problem, and religious services of course. I think over time its become increasingly clear that infection rates are clearly associated with the viral dose, the length of exposure and being in enclosed environments. While detection of viral particles in the air isn't a good indicator of infectivity the circumstantial evidence has become overwhelming. In fact several countries had altered their guidelines before WHO got its act together.

Its a bit inevitable that we appear to be playing catchup all the time, we don't know enough about this infection but the idea of air born spread is providing a rational for the increased infection rate in the warmest states in the US. People stay indoors to avoid the heat, its also starting to inform the predictions of a second wave in winter, when cold weather causes the same behaviour.
 
  • #12
.Scott
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"As a doctor or a scientist, it is unethical to send people (even enthusiastic, well-informed volunteers) into harm's way for the greater good. "

So was it unethical to send me to Vietnam for two years or send someone to a more popular war? I like many vets would gladly give my life for the greater good in the "war" with Covid-19.
You may have misinterpreted my statement. I was not saying that I was a doctor or a scientist. I was describing an aspect of the role of doctor or scientists. So it would have been unethical for someone acting as a doctor or a scientists to send you to Vietnam. But entirely ethical (but perhaps not well-advised) for a POTUS to send you there.
 

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