Aerosolized Transmission

This forum is to discuss general things concerning TSOI.
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Aerosolized Transmission

Post by trader32176 »

Choir practice in Spain infects 30 of 41 members with virus

9/24/20 ... syndicated

MADRID (AP) — At least 30 of 41 members of a gospel choir in northeastern Spain have contracted coronavirus following a rehearsal indoors with little air circulation, local authorities and the chorus say.

The River Troupe Gospel, a volunteer gospel group, rehearsed on Sept. 11 ahead of an open-air performance two days later for a local festival in Sallent, a town in the province of Barcelona. It was their first public show since the beginning of the pandemic.

After one member of the chorus tested positive following the Sept. 13 performance, more than 40 other members and their close contacts went into isolation, the chorus said. Since then, at least 30 singers have tested positive, the Sallent municipal government said.

Although the chorus claims that it complied with most health safety measures — temperature checks on arrival, hand washing, social distancing between each member and masks on for most of the rehearsal — the venue’s windows were closed to avoid moths and mosquitoes. The group said it had switched on air conditioning to fight the heat.

It was not known if any relatives of the singers also became infected.

Experts have acknowledged that in certain circumstances, like during medical procedures or when people are in close indoor spaces singing or shouting, COVID-19 can spread in the air.
Choir practices in the U.S., for example, have been identified as a superspreading event in which hundreds of people were later sickened by the virus.

How often coronavirus can spread from person to person through the air, and not just from people speaking or coughing close to each other, is being closely examined by health experts and still a matter of scientific debate.

The Sallent town hall believes there was no risk infection during the Sept. 13 performance following the rehearsal because it was outdoors with required safety measures.

Spain is battling a second wave of the new coronavirus that is spreading faster there than anywhere in Europe. The country is set to surpass 700,000 cases on Thursday and has a confirmed death toll of 31,034 fatalities.

Experts say all numbers understate the true impact of the virus, due to limited testing and missed cases, among other factors.
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Aerosolized Transmission

Post by trader32176 »

Evaporation is critical for coronavirus transmission in colder months


Dr. Talib Dbouk and Professor Dimitris Drikakis speak to News-Medical about their research efforts during the COVID-19 pandemic, and how evaporation is essential for coronavirus transmission in the winter.

What provoked your research into the transmission of viruses, and in particular, that of the coronavirus?

As researchers, our mission is to investigate and better understand the flow physics and transmission dynamics of viruses.

What mainly provoked our research is our interest to contribute to stopping the rapid spread of the deadly coronavirus, which has been causing the death of hundreds of thousands of people around the globe unexpectedly and has had significant financial implications.

Why are winter virus infections more common than those in the summer months?

We found from our research results that there exists a combination of factors affecting virus transmission. It is related to the wind speed, air temperature, and relative humidity.

During the winter season, especially in cold winter countries like North and Central Europe, North America, and Russia, people spend most of their time indoors. The indoor environment usually has a specific microclimate, e.g. heated to an average temperature between 23°C and 25 °C, and the relative humidity can reach up to 65% or more.

During the summer, people have more of a tendency to go outside, and there is no heating indoors, but air-conditioning leads to relatively low humidity values. During the summer, air temperature can go above 30 °C, and the relative humidity can decrease below 50% in some places.

Our research showed that the viability of coronavirus is higher at low air temperature values below or equal to 25°C, and at high relative humidity values greater than or equal to 65%. This explains clearly why winter virus infections are more common than those during the summer months.

Moreover, we also illustrated the role of wind speed (that is usually higher during winter months) contributes more to the virus transmission rate.

Why has research into the importance of airborne droplet transmission been scarce?

Indeed, we have conducted a comprehensive literature survey and surprisingly found that research focusing on the importance of airborne droplet transmission has been scarce. Several factors might explain this, mainly:

Previously, researchers focused on more traditional biological aspects of the virus and gave secondary importance (or none at all) to factors such as the airborne transmission, fluid dynamics, and heat transfer.
The fact that the last pandemic of COVID-19 was very deadly and is causing both deaths and financial losses has prompted researchers like us to investigate aspects of virus transmission that are not understood at all.
In the past, the lack of advanced computational fluid dynamics methods and expensive computing hardware to perform complex fluid dynamics and heat transfer simulations also hindered progress in the area of simulation of fluid dynamics and heat transfer. There was significant progress in the above areas in the past decade or so. This now helps perform detailed simulation studies.

Can you describe how you carried out your research into coronavirus viability?

We developed an advanced CFD (Computational Fluid Dynamics) numerical platform that allows the prediction of coronavirus concentration variation in contaminated airborne saliva droplets (after being expelled into the air).

The computational models developed in the framework of this research allow the quantification of the coronavirus viability as a function of air temperature, relative humidity, and the surrounding wind speed or air circulation in indoor and outdoor environments.

What did you discover from your research?

We discovered that the viability of coronavirus depends on the combination of the air temperature, the wind speed, and the relative humidity.

How is the coronavirus transmitted by evaporation?

The coronavirus is transmitted through airborne contaminated saliva droplets that contain a specific concentration of virus particles. The virus particle carriers which are the saliva droplets, when expelled from an infected person, fly in the air.

While traveling in the air, they witness the evaporation process, which can be linked to the coronavirus viability.

How will your research help further our understanding of coronavirus transmission?

Our research through the newly developed CFD simulation platform allows future critical investigations such as to defining better social distancing safety distance and rules that should be dynamic, and not fixed.

The above depends on the indoor and outdoor conditions, e.g. related to the surrounding environment temperature, its relative humidity, and its air circulation rate amongst others.

Do you believe that factors such as wind speed and humidity should be considered when evaluating social distancing guidelines?

Of course, because the safety distance and rules significantly depend on the indoor and outdoor conditions (e.g. related to the surrounding environment temperature, its relative humidity, and its air circulation rate amongst others).

What can people do to protect themselves from increased virus survival and transmission rates in the upcoming winter months?

For people do to protect themselves from increased virus survival and transmission rates in the upcoming winter months, we advise:

a- To respect the social distance, at least 2 meters if no air circulation is present, and in case of air or wind speeds, this social distance should be up to 6 meters depending on the wind speed. We have published another detailed study on this subject:

b- Avoid conditions of high relative humidity, especially indoor

c- Avoid places of low temperature.

d- Avoid crowded places

e- Wear protective face masks, especially in situations where there is unavoidable close contact with other people. See our previous study on face masks:

f- Avoid forced air convection or forced air circulation in closed indoor places.

g- Apply natural ventilation and air circulation indoors

What are the next steps in your research?

Our next steps include investigation of other physical mechanisms and their interaction with virus transmission such as air pollution.

(Read this earlier article on air pollution / Particulate Matter / PM here : First data analysis about possible COVID-19 virus airborne diffusion due to air particulate matter (PM): The case of Lombardy (Italy)

May 7, 2020 )

Where can readers find more information?
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Aerosolized Transmission

Post by trader32176 »

Ventilation systems may increase the risk of exposure to novel coronavirus

9/29/20 ... virus.aspx

Ventilation systems in many modern office buildings, which are designed to keep temperatures comfortable and increase energy efficiency, may increase the risk of exposure to the coronavirus, particularly during the coming winter, according to research published in the Journal of Fluid Mechanics.

A team from the University of Cambridge found that widely-used 'mixing ventilation' systems, which are designed to keep conditions uniform in all parts of the room, disperse airborne contaminants evenly throughout the space. These contaminants may include droplets and aerosols, potentially containing viruses.

The research has highlighted the importance of good ventilation and mask-wearing in keeping the contaminant concentration to a minimum level and hence mitigating the risk of transmission of SARS-CoV-2, the virus that causes COVID-19.

The evidence increasingly indicates that the virus is spread primarily through larger droplets and smaller aerosols, which are expelled when we cough, sneeze, laugh, talk or breathe. In addition, the data available so far indicate that indoor transmission is far more common than outdoor transmission, which is likely due to increased exposure times and decreased dispersion rates for droplets and aerosols.

" As winter approaches in the northern hemisphere and people start spending more time inside, understanding the role of ventilation is critical to estimating the risk of contracting the virus and helping slow its spread."

- Professor Paul Linden, Cambridge's Department of Applied Mathematics and Theoretical Physics (DAMTP)

"While direct monitoring of droplets and aerosols in indoor spaces is difficult, we exhale carbon dioxide that can easily be measured and used as an indicator of the risk of infection. Small respiratory aerosols containing the virus are transported along with the carbon dioxide produced by breathing, and are carried around a room by ventilation flows. Insufficient ventilation can lead to high carbon dioxide concentration, which in turn could increase the risk of exposure to the virus."

The team showed that airflow in rooms is complex and depends on the placement of vents, windows and doors, and on convective flows generated by heat emitted by people and equipment in a building. Other variables, such as people moving or talking, doors opening or closing, or changes in outdoor conditions for naturally ventilated buildings, affect these flows and consequently influence the risk of exposure to the virus.

Ventilation, whether driven by wind or heat generated within the building or by mechanical systems, works in one of two main modes. Mixing ventilation is the most common, where vents are placed to keep the air in a space well mixed so that temperature and contaminant concentrations are kept uniform throughout the space.

The second mode, displacement ventilation, has vents placed at the bottom and the top of a room, creating a cooler lower zone and a warmer upper zone, and warm air is extracted through the top part of the room. As our exhaled breath is also warm, most of it accumulates in the upper zone. Provided the interface between the zones is high enough, contaminated air can be extracted by the ventilation system rather than breathed in by someone else. The study suggests that when designed properly, displacement ventilation could reduce the risk of mixing and cross-contamination of breath, thereby mitigating the risk of exposure.

Buildings have been built with energy efficiency in mind. Along with improved construction standards, this has led to buildings that are more airtight and more comfortable for the occupants. In the past few years however, reducing indoor air pollution levels has become the primary concern for designers of ventilation systems.

"These two concerns are related, but different, and there is tension between them, which has been highlighted during the pandemic," said Dr Rajesh Bhagat, also from DAMTP. "Maximising ventilation, while at the same time keeping temperatures at a comfortable level without excessive energy consumption is a difficult balance to strike."

In light of this, the Cambridge researchers took some of their earlier work on ventilation for efficiency and reinterpreted it for air quality, in order to determine the effects of ventilation on the distribution of airborne contaminants in a space.

"In order to model how the coronavirus or similar viruses spread indoors, you need to know where people's breath goes when they exhale, and how that changes depending on ventilation," said Linden. "Using these data, we can estimate the risk of catching the virus while indoors."

The researchers explored a range of different modes of exhalation: nasal breathing, speaking and laughing, each both with and without a mask. By imaging the heat associated with the exhaled breath, they could see how it moves through the space in each case. If the person was moving around the room, the distribution of exhaled breath was markedly different as it became captured in their wake.

"You can see the change in temperature and density when someone breathes out warm air - it refracts the light and you can measure it," said Bhagat. "When sitting still, humans give off heat, and since hot air rises, when you exhale, the breath rises and accumulates near the ceiling."

Their results show that room flows are turbulent and can change dramatically depending on the movement of the occupants, the type of ventilation, the opening and closing of doors and, for naturally ventilated spaces, changes in outdoor conditions.

The researchers found that masks are effective at reducing the spread of exhaled breath, and therefore droplets.

"One thing we could clearly see is that one of the ways that masks work is by stopping the breath's momentum," said Linden. "While pretty much all masks will have a certain amount of leakage through the top and sides, it doesn't matter that much, because slowing the momentum of any exhaled contaminants reduces the chance of any direct exchange of aerosols and droplets as the breath remains in the body's thermal plume and is carried upwards towards the ceiling. Additionally, masks stop larger droplets, and a three-layered mask decreases the amount of those contaminants that are recirculated through the room by ventilation."

The researchers found that laughing, in particular, creates a large disturbance, suggesting that if an infected person without a mask was laughing indoors, it would greatly increase the risk of transmission.

"Keep windows open and wear a mask appears to be the best advice," said Linden. "Clearly that's less of a problem in the summer months, but it's a cause for concern in the winter months."

The team are now working with the Department for Transport looking at the impacts of ventilation on aerosol transport in trains and with the Department for Education to assess risks in schools this coming winter.
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Aerosolized Transmission

Post by trader32176 »

Nasal calcium-rich salts effectively eliminate airborne particles from airways

9/29/20 ... rways.aspx

In a paper published in Molecular Frontiers Journal, researchers from Cambridge, Massachusetts have discovered a more effective way of eliminating airborne particles from airways using nasal calcium-rich salts called FEND, which have potential applications in the fight against Covid-19.

Sensory Cloud, creators of FEND and a Boston-based technology startup that designs solutions to problems of human wellbeing and healthcare through pioneering discoveries at the frontiers of olfaction and respiratory biology, studied the effectiveness of nasal administration of physiological salts at reducing airborne particles from exhaled breath including the sub-micron aerosolized particles that are ineffectively filtered by cloth face masks. Lead authors of the paper are Dr. David Edwards (John A. Paulson School of Engineering, Harvard University) and Dr. Robert Langer (Department of Chemical Engineering, MIT),

Ninety-two men, women and children were observed in three separate studies showcasing the use of FEND in various situations: in the workplace, quarantining at home, and in comparison to cloth face masks. The studies assessed how FEND, a drug-free calcium-enriched nasal salt, would interact with airway lining mucus to cleanse the airways of bioaerosols. The results showed a reduction of exhaled aerosol particles of up to 99%, with an overall reduction of exhaled particles in the largest cohort of human subjects (76 workers) of around 75%.

" The findings, which build on an earlier study this summer, suggest that we can provide what is, in effect, a nasal filter to protect at-risk populations from viral carrying aerosols. Access to a new hygiene protocol for reducing the spread of these smallest particles, which can otherwise be dispersed into indoor air and enter deep into our lungs, can be an important intervention as we head back to work and school, as winter approaches, and as troubling data about rates of infection continue to emerge."

- Dr. David Edwards, Founder, Sensory Cloud

In the first study, 76 COVID-negative volunteers (including 74 workers and two children) from No Evil Foods in Asheville, NC, ages 15-66, were recruited. Prior to the nasal hygiene intervention, exhaled aerosol from the 76 workers followed a classical "super spreading" distribution, with 20% of participants accounting for 80% of the overall exhaled aerosol. Within the "super spreader" group, half of the individuals (or the top 10% of exhaled particle producers) were found to be responsible for 80% of the super spreader production - or 64% of the overall production. The 76 volunteers then received FEND, a drug-free nasal saline hygiene formulation comprised of calcium chloride and sodium chloride in distilled water and administered via a mist of 9-10 micron diameter droplets by a hand-held mister.

The FEND intervention suppressed 84% of exhaled aerosols for the highest producing super-spreaders and 78% overall for all super-spreaders. Overall, exhaled aerosols among all participants did not change after a nasal saline control intervention, Simply Saline from Arm & Hammer, a nasal spray of isotonic sodium chloride.

"Health and safety is a huge priority at No Evil Foods," said Sadrah Schadel, co-founder and Chief Creative Officer of No Evil Foods. "Having the chance to actually see FEND work, clearing particles from our exhaled breath, was an overwhelmingly positive experience for our team."

The second study evaluated the exhaled aerosols of a volunteer family of four in quarantine with one COVID-positive mother. The study followed the family for five days starting at eight days post-symptoms for the mother. The mother's exhaled aerosols showed extremely high output on days eight and nine. After receiving the FEND intervention, her levels decreased to average baseline levels for a COVID-negative patient, with suppression lasting several hours following the intervention.

The final study compared the use of FEND to surgical mask use in 12 children and adults. The surgical masks reduced overall exhaled particles by around 34% for the group, while FEND reduced overall exhaled particles by 46% -- with one individual showing no statistical difference on using the mask or FEND, possibly for failure to administer properly. Excluding the outlier subject, exhaled aerosols were reduced by 59% when wearing masks and 87% following the FEND intervention. The differential benefit of FEND was due to its more effective reduction in sub-micron aerosol particles, given that most exhaled aerosol particles for all individuals are sub-micron.

The paper concludes that FEND can be an important addition to current COVID-19 hygiene protocols of mask wearing, hand washing, and social distancing. FEND adds to the efficacy of masks at reducing the penetration of respiratory droplets into the lungs or back into the environment and provides an added layer of defense for when mask wearing is not a possibility.

"We continue to support human volunteer studies in the USA and overseas, exploring unique hygiene protocols for collaborative teams, and deepening our understanding of nasal salt hygiene among those infected with COVID-19," said Edwards. "As FEND comes to market in coming weeks, we will prioritize distribution to healthcare professionals, and other essential workers in the USA and in countries around the world that are hardest hit by the COVID-19 pandemic. As we scale up production, we hope also to be helpful to clearing the air for children and teachers in public schools around the world."
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Aerosolized Transmission

Post by trader32176 »

New research supports evidence of airborne transmission of COVID-19 in enclosed spaces

9/30/20 ... paces.aspx

New research from the University of Georgia supports growing evidence for airborne transmission of COVID-19 in enclosed spaces.

Researchers were able to link a community outbreak of COVID-19 in China to a source patient who likely spread the virus to fellow bus riders through the bus's air conditioning system.

" The possibility of airborne transmission has long been suspected, but with limited empirical evidence. Our study provided epidemiologic evidence of transmission over long distances, which was likely airborne."

- Ye Shen, Study Lead Author and Associate Professor, Department of Epidemiology and Biostatistics, UGA's College of Public Health

The study, which was published recently in JAMA Internal Medicine, calls into question the prevailing thought on how COVID-19 can spread.

"It was largely believed that close contact through droplets is a major route of transmission for COVID-19. However, the widely adopted social distancing and hand washing did not effectively prevent the transmission globally. Instead, the number of new COVID-19 cases increased steadily," said Shen.

Shen and his co-authors worked with epidemiologists from two regional Centers for Disease Control and Prevention in China to trace infections following a large outdoor worship event in Zhejiang province. Some of the attendees, it turns out, took two buses to the event creating a unique natural experiment for the researchers.

Both buses had closed windows and had air conditioning running, said Changwei Li, an associate professor of epidemiology at Tulane University and study co-author - but one bus carried a patient infected with the virus, and the other did not.

Of the passengers who later got sick, the majority of them rode on the same bus as the source patient.
Even though the two groups later mixed in with the larger crowd at the worship event, the number of new cases attributed to the event were much lower, suggesting that the bus was the major point of transmission.

Further, some of the bus passengers who later showed symptoms of COVID-19, the authors found, were not sitting close to the infected passenger.

These findings highlight scenarios where COVID-19 could be spread through fine aerosol particles being circulated in an enclosed space, and as the weather turns colder, Shen and Li hope this work will persuade more people to wear face masks in public areas, particularly in indoor spaces.

"Understanding the transmission routes of COVID-19 is critical to contain the pandemic, so that effective prevention strategies can be developed targeting all potential transmission routes," said Shen. "Our findings provide solid support for wearing face covering in enclosed environments with poor ventilation."
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Aerosolized Transmission

Post by trader32176 »

Google Doc to educate the public about airborne coronavirus transmission

The evidence that the coronavirus spreads through the air has been mounting for months—but official guidance has barely shifted. Jose-Luis Jimenez has had enough.

10/2/20 ... nsmission/

The evidence that the coronavirus spreads through the air has been mounting for months. However, the official guidance from the World Health Organization and Centers for Disease Control is still that droplets are the main route of transmission. In fact, the CDC changed its website last month to acknowledge airborne transmission as a route for covid-19 infections but removed the new guidance just days later, saying it had been posted in error. An official told CNN that it “wasn't ready to be posted.” All clear?

Back in July, a group of 239 experts sent an open letter to the WHO imploring it to acknowledge airborne transmission. Three months later, the WHO’s guidance has changed subtly but still only suggests airborne transmission plays a limited role. Rather than wait for officialdom to catch up, one of those signatories, Jose-Luis Jimenez, a chemistry professor at the University of Colorado, Boulder, who has studied aerosols for 20 years, decided to go straight to the public with the latest advice on how people can protect themselves and those around them. He convened a group of nine other experts in the field to create this open-access Google Doc offering comprehensive advice on what you need to know about aerosol transmission, from best practices for masks to whether it’s safe to travel by airplane.

We spoke to him about why he created the document, and the response he’s had so far. The conversation has been condensed and lightly edited for clarity.

Why did you create this document?

A lot of people were asking questions, so I thought it made sense to put them in one place. It means you don’t have to keep repeating yourself, and you can tweak the document and improve it over time. We [aerosol transmission experts] were answering so many questions on Twitter and via email. I’ve had several thousand emails and Twitter questions. But the answer is so often the same. Some of the coauthors I found through the WHO open letter, others I found via Twitter, and I proposed to them, “What do you think about putting our research together, so we don’t have to keep repeating ourselves so much?” A few of them said yes, so I set it up, put in some questions, and then others starting adding theirs in too. When we saw it was useful, we made it public. We update the document all the time. We’re effectively having to be a little WHO or CDC. We’re saying the things that they should be saying. This is frustrating, but it’s the situation we find ourselves in. These organizations have been flat-out refusing to consider if aerosol transmission is important, which leaves people unprotected. So we feel it’s our duty to communicate directly with the public.

How are people using it?

We’ve advertised the document as much as possible through Twitter, emails, and asking journalists to help. That’s how most members of the public see it. There are always more than 100 people looking at it whenever I check, so we know a lot of people are reading it. And people have said it’s very useful. A lot of doctors have said it’s a good resource. And Google Translate means it can be automatically translated it into any language. Every time I give an interview in a new country, people are shocked transmission is mostly through aerosols.

Why did you make this document instead of going down the traditional science publishing route?

Science publishing is very slow. For the scale of the pandemic, people need information today. And publishers can be cryptic. They all have their own rules. In reality, you can only publish things that have not been published before, so it’s not a good way to answer questions from the public. And crucially, it needed to be updateable so we can answer people’s questions as they come. In a journal, it would be frozen.

What have been your main frustrations with the response to the evidence around airborne transmission?

Ever since we wrote that letter, signed by 239 scientists, I have been waiting for the landslide. The evidence is now simply overwhelming that the virus is spread through aerosols. The idea it’s mainly droplets is a myth. It’s an error from 1910 made by Charles Chapin, who wrote a book called The Sources and Modes of Infection. In that book, he associated the risk of infection with droplets. He said, admitting later it had been without evidence, that aerosol transmission is almost impossible, and anyone who says otherwise has to prove it. And that has become dogma ever since. It’s almost a superstition. To this day it’s still what the CDC says.

I’m still waiting for that landslide, where suddenly everyone moves and there’s a huge change. But it hasn’t happened yet. Germany has started saying that good ventilation is the cheapest and best method to reduce the spread of the virus—and that only makes sense if you think it’s mostly spread by aerosols, not droplets or surfaces. The CDC published some guidelines which were confusing, which said inhalation is the main way it spreads—and that means aerosols, as only they can be inhaled—so they were admitting aerosols were the main mode of transmission. Then they took it down. We don’t know if it’s because of politics or dogmatic scientists who refuse to let go of droplets.

Aerosol transmission is the main way this virus spreads: the only question if it’s 70%, 80%, or 90%. Ballistic droplets are a negligible way to spread the virus. They only spread if someone coughs or sneezes on you. They drop to the ground, whereas aerosols linger. If you look at superspreading events, for example the Washington choir case, it is impossible they are being spread by droplets. For 52 people to get infected, it has to be by aerosols. If droplets were important, it would matter less if you are inside or outside, and you’d expect transmission to happen a lot more outdoors. But if you go outside, transmission drops tremendously. The evidence is clear. It’s scandalous and absurd these agencies refuse to give correct guidance.

What are the most important parts of the document to understand for personal safety?

The thing people need to understand is aerosol transmission is like everyone breathing out cigarette smoke, and you want to breathe in as little of others’ as possible. Everyone you are around, imagine they are breathing smoke, and try to avoid it. It’s not good enough to just give people guidelines; you need to explain the actual science behind it, too.

The second most important thing is the recommendations section—how to interpret the science for any given situation. Avoid anything that involves breathing in a lot of other people’s breath. Do things outdoors. But the most important things are free. Wear the mask you already have when you are inside public spaces, and open a window. If we did those, transmission would go down dramatically. Things like ventilation and air filtering matter, but the main things we can do cost nothing.

And finally, perhaps not for the general public but for people who want to understand how we got here—look at the history, in section 1.3 and 1.4 of the document. It is critical, and it explains why the WHO and CDC are not budging. I wonder what percentage of the global population we could reach with our advice. We’ve reached millions, but it’s still a tiny fraction. And if the CDC, WHO, and local health agencies don’t change their guidance, it really defeats the purpose. It makes me so angry.
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Aerosolized Transmission

Post by trader32176 »

Researchers quantify aerosols generated during anesthetic procedures

10/7/20 ... dures.aspx

Since the outset of the COVID-19 pandemic, there has been much debate about the danger to hospital staff from anesthetic procedures. Concerns include that placing a tube in the patient's airway (intubation) before surgery or removing it at the end (extubation) may produce a fine mist of small particles (called aerosols) and spread the COVID-19 virus to nearby staff.

This risk was judged so high that the procedures are classified 'aerosol generating procedures' (AGPs) for which respirators and high level personal protective equipment (PPE) are worn routinely, and after which surgery stops while the operating room is cleared of aerosols and special cleaning is undertaken.

These requirements have dramatically slowed surgery and contributed to enormous waiting lists for surgery in the UK National Health Service (NHS), as well as similar problems in hospitals worldwide. Despite the presumed risk, no direct measurements of aerosols have ever been made during anesthetic care in a hospital.

New research published in Anaesthesia (a journal of the Association of Anaesthetists) shows that these procedures may only produce a fraction of the aerosols previously thought, much less than would be produced during a single regular cough.

This brings into question whether the procedures should be designated AGPs and provides an opportunity to dramatically speed up surgery.

The study is by Dr Jules Brown (North Bristol NHS Trust, Bristol, UK) working with Professor Jonathan Reid (Bristol Aerosol Research Centre, School of Chemistry, University of Bristol), Professor Tim Cook (Royal United Hospitals Bath NHS Foundation Trust, Bath, UK, and School of Medicine, University of Bristol, UK) and Professor Tony Pickering, (School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK), and colleagues.

To address this lack of evidence, the authors conducted real-time, high-resolution environmental monitoring in ultraclean ventilation operating theatres during anaesthesia procedures for insertion and removal of the tube from the patient's airway.

The authors also studied procedures such as suction of the airway and 'mask ventilation' when the anaesthetist takes over the patients breathing before tube insertion.

Put simply, they were able to quantify the aerosols generated during all these procedures, in a real clinical setting, and compare this to the aerosols produced by a single cough. Recordings were made of 19 tube insertions and 14 tube removals.

Against expectations, the authors found that tube insertion generated approximately one thousandth of the aerosol generated by a single cough. Tube removal produced more aerosol, especially when accompanied by a weak cough, but still less than 25% of that produced by a voluntary cough.

"These findings should trigger a re-evaluation of when it is necessary to use specific measures to protect against viral transmission by aerosol in operating rooms.
De-escalation of these high-level protective measures would have a substantial impact on our ability to deliver healthcare to patients within the NHS and internationally," explain the authors.

"If we can agree these procedures do not generate aerosols we can reduce the PPE we wear and we can eliminate the major delays that currently exist between one patient leaving the operating room and starting the next case," they add.

"The results suggest that during anaesthesia tube insertion should not be considered a high-risk procedure," say the authors. "We detected no increases in aerosolised particles during face-mask ventilation, airway suction or repeated attempts at intubation. This reflects typical clinical practice by anaesthetists with a range of experience, providing further reassurance regarding the low level of aerosol generation."

The authors explain that with tube removal, a cough can occur as the patient's natural breathing reflexes return, and this does produce aerosols that are detectable for around five seconds.

They say: "The risk of aerosol exposure for staff can be further reduced by using techniques that reduce coughing or by the anaesthetist simply stepping away, as our study showed much reduced particle numbers behind the patient's head compared to above their face."

The authors note some limitations to their study. "It should be acknowledged that while we have provided reassuring evidence around aerosol generation during these procedures, we have not directly studied the risk of SARS-CoV-2 transmission and our interpretation rests on the widely accepted link between aerosol generation and infection risk," they explain.

For safety reasons, this study was not performed on patients with COVID-19, but on other patients to demonstrate the aerosols actually produced during these procedures which are common during anaesthesia and in intensive care.

They conclude: "The precautions many hospitals worldwide have introduced to mitigate the risks posed by viral aerosols have reduced operating theatre turnover, decreased hospital productivity and increased waiting times for elective and cancer surgery."

"A further important consideration relates to the cost and limited supply of PPE which has to be targeted to appropriate healthcare settings on the basis of risk. Our results raise important questions about the need for these precautions at the start and end of anaesthesia. These results should help inform future PPE guidelines by providing evidence on the relative risk of aerosol generation associated with tracheal intubation and extubation."
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Aerosolized Transmission

Post by trader32176 »

Detection of SARS-CoV-2 viral persistence in built environments

10/8/20 ... ments.aspx

As per the latest WHO reports, coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected over 36.37 million people and caused over 1 million deaths across the world.

The virus emerged in Wuhan, China, in late December 2019 and has spread to most countries in a relatively short time. SARS-CoV-2 spreads from person to person through respiratory droplets laden with the virus.

Recent studies show that it is also transmitted through contact on surfaces (fomites), as the virus can remain infectious up to 72 hours - a highly plausible cause for the global spread of the disease. With this information, it is now essential to have a protocol to identify SARS-CoV-2 from surfaces in the built environment efficiently.

Built environments refer to man-made environments that provide the setting for human activity - ranging from buildings, cities, and beyond. These structures include surfaces made of materials such as bare stainless steel, painted stainless steel, plastics, copper, wood, and reinforced fiberglass.

In a recent paper in an open-access journal, mSystems, published by The American Society for Microbiology, Ceth W. Parker et al. show challenges in recovering the virus, change in infectivity, and the case of viral persistence in built environments.

The researchers developed a standardized end-to-end (E2E) protocol for the detection of SARS-CoV-2 from built environmental surfaces and determined the minimum number of RNA copies needed on surface/fomites to positively detect the virus within the limit of detection of the assay used in the study.

"As we all know, SARS CoV-2 is of worldwide concern," said principal investigator of the study Dr. Kasthuri Venkateswaran, a senior research scientist at NASA's Jet Propulsion Laboratory (JPL) in Southern California.

The researchers used a noninfectious and replication-deficient virus used as a surrogate for the SARS-CoV-2 virus. The representative test surfaces inoculated with this virus are: bare 302 stainless steel, painted 302 stainless steel (white acrylic paint), polyethylene terephthalate modified with glycol (PETG), and fiberglass-reinforced plastic (FRP).

To monitor the SARS-CoV-2 on surfaces, the effective combination of methodology included an Isohelix swab collection tool, DNA/RNA Shield as a preservative, an automated system for RNA extraction, and reverse transcriptase quantitative PCR (RT-qPCR) as the detection assay.

"Our group adapted the CDC-approved reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) methodology and then tested the efficacy of RT-qPCR in detecting SARS CoV-2 from various environmental surface samples," said Dr. Ceth W. Parker, a postdoctoral fellow at JPL.

In this comprehensive end-to-end study, the researchers show that the effective combination for monitoring SARS-CoV-2 on surfaces required a minimum of 1,000 viral particles per 25 cm2 for successfully detecting the virus from the surfaces.

When this method was employed to evaluate 368 samples collected from various built environmental surfaces, all the samples turned negative for the viral fragment. It is also found in this study that the debris found on these surfaces negatively impacted the recovery of RNA; Amerstat demonstrated the highest inhibition (>90%) when challenged with an inactivated viral control.

"We tested these surfaces by seeding inactivated noninfectious SARS CoV-2 particles and then determining how well we could actually recover them from the surfaces," said Dr. Parker. "It takes a minimum of 1,000 viral particles per 25 cm2 to effectively and reproducibly detect SARS-CoV-2 virus on the surface. We found that viral RNA can persist on surfaces for at least 8 days. We also found that inhibitory substances and debris have to be taken into account on the surfaces they are being tested on."

Despite the observed longevity of the viral fragment on surfaces, the authors report that the surfaces were either void of virus or below the detection limit of the assay.

The data from this study reflects an overall E2E process efficiency of 0.1%. The E2E assay was also repeated similarly by an independent laboratory for reproducibility and verification purposes.

The results obtained from this evaluation were comparable or equivalent to the results presented in this study.

This detailed study provides necessary protocols for monitoring the SARS-CoV-2 virus on various materials of surfaces and the capacity to retain viral RNA and also allow for effective disinfection.

The information is valuable during this current pandemic - if the virions remain infectious on surfaces for days leading to human infection from contact with infected surfaces?

Because no policy is set for environmental surface monitoring of the virus, a thorough approach is outlined in this study to characterize and develop a practical methodology to understand the viral persistence in built environments.

Such intensive research on SARS-CoV-2 is essential to understand the pathogenic mechanisms and epidemiological behavior - these will help develop effective preventive and therapeutic strategies.
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Aerosolized Transmission

Post by trader32176 »

Study reveals a list of medical procedures that pose COVID-19 risk to health-care providers

10/14/20 ... iders.aspx

Autopsy, airway suctioning and cardiopulmonary resuscitation are among the list of medical procedures that pose a risk of spreading COVID-19 from a patient to their health-care provider by creating aerosols.

According to new research published in the journal BMJ Open Respiratory Research by an international team of experts including occupational health, preventive medicine and infectious disease specialists.

The team, led by University of Alberta medicine professor Sebastian Straube, carried out a systematic review of public health guidelines, research papers and policy documents from around the globe to determine which procedures are classified as aerosol-generating.

What we sought to do was to understand which procedures generate aerosols and therefore require a higher grade of personal protective equipment."

Sebastian Straube, Professor and Head, Preventive Medicine Division, Faculty of Medicine & Dentistry, University of Alberta

"Where there is 80 per cent agreement from a number of different source documents, we are reasonably confident that, yes, the classification of these procedures as aerosol-generating is accurate."

Straube recommended that further research be done on the short list of procedures for which they found no consensus, such as taking throat swabs.

The team of 19 Canadian, British, American and other researchers includes renowned Oxford University primary care expert Trisha Greenhalgh and first author Tanya Jackson, Straube's research associate. They came together to share their expertise at the outset of the COVID-19 pandemic and have published rapid reviews on the efficacy of respirator masks versus standard surgical masks, eye protection and shoe covers.

"We are providing a summary of the evidence to inform policy-making decisions and guideline development," Straube said.

An aerosol is a suspension of fine solid or liquid particles in air, Straube said. "Larger particles settle in a reasonably short distance, and are referred to as 'droplets' in the infection control context," the paper states. "Smaller particles can travel as aerosols on air currents, remaining in the air for longer and distributing over a wide area."

Straube said the goal is to prevent health-care workers from becoming infected with COVID-19, both to protect them from severe disease as individuals and to maintain staffing levels in health-care systems during the pandemic.

Health-care workers who perform aerosol-generating procedures should wear filtering facepiece respirators, known as N-95 masks in North America, Straube said, along with other personal protective equipment (PPE) such as gloves, gowns and eye protection.

"PPE is typically displayed at the bottom rung of the hierarchy of hazard controls," Straube said.

"Elimination of the hazard or substitution as well as engineering and administrative approaches to hazard control should also be considered."

The U of A contribution to the research was funded by a grant from the Workers' Compensation Board of Alberta.


University of Alberta Faculty of Medicine & Dentistry

Journal reference:

Jackson, T., et al. (2020) Classification of aerosol-generating procedures: a rapid systematic review. BMJ Open Respiratory Research.
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Joined: Fri Jun 26, 2020 5:22 am

Aerosolized Transmission

Post by trader32176 »

Scientists use dehumidifiers to detect airborne SARS-CoV-2

10/14/20 ... CoV-2.aspx

The coronavirus disease (COVID-19) primarily spreads through respiratory droplets when infected people cough and sneezes. A recent update from health agencies confirms that the virus can spread through airborne particles.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can spread through aerosols that can hang in the air for long periods
. However, it has not been easy to assess the actual environmental threat since there are no procedures and tests present.

Now, a team of researchers at the University of Maryland presented a simple approach that can potentially provide information about the prevalence of SARS-CoV-2 in the atmosphere at any location.

The study

There are shared similarities between SARS-CoV-2 and other coronaviruses such as the Middle East respiratory syndrome coronavirus (MERS-CoV) and the severe acute respiratory syndrome coronavirus (SARS-CoV), both of which were found to be airborne and could spread even in long distances. It is essential to study how SARS-CoV-2 could spread to reduce the risk of infection.

Published on the pre-print server medRxiv*, the researchers aimed to see the extent and prevalence of SARS-CoV-2 infection in the air. To arrive at the study findings, the researchers used a portable dehumidifier as a convenient and affordable tool to collect airborne SARS-CoV-2 virus in the condensate.

They situated the dehumidifiers in selected areas of a hospital ward with patients who reported flu-like illness, which could be COVID-19. These dehumidifiers stayed there over three separate periods in one week. The team studied the samples frequently for both the virus envelope protein and SARS-CoV-2 RNA.

What the study found

The researchers have found that in several samples across separate areas, the condensate from dehumidifiers tested positive for the presence of SARS-Cov-2.

“Our results point to a facile pool testing method to sample the air in any location in the world and assess the presence and concentration of the infectious agent to obtain quantitative risk assessment of exposure, designate zones as ‘hot spots’ and minimize the need for individual testing which may often be time-consuming, expensive and laborious,” the researchers concluded in the study.

The team believes that the simple test highlights the need for an effective but easy-to-do technique to detect the virus in high-density environments. Being able to understand the day-to-day exposure risk to virus aerosols is crucial to implement fast and reliable interventions to contain the spread of the virus, as well as safeguard human health.

Further, the method could be used when there is the unavailability of individual testing in many remote areas. This way, the presence of the virus particle in the air could spark infection control measures to stop the spread of the virus.

Overall, there are now more than 38.4 million people who have been infected with SARS-CoV-2 and over 1 million people who died from complications.

The United States remains the nation with the highest number of cases, topping 7.9 million, followed by India, with over 7.23 million infections.

Airborne spread

Ten months into the pandemic, many health experts described that COVID-19 could spread via aerosols, given the fast spread of the virus across countries. Many cases were traced back to enclosed areas with little ventilation, hinting that the virus may have spread through the air.

Both the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC) said that there are pieces of evidence that show the airborne transmission of SARS-CoV-2. The agencies recommend that people should wash their hands regularly, maintain social distancing, and always wear a mask, especially when going out. Further, the agencies emphasized that staying indoors in areas where there is poor ventilation could elevate the risk of contracting the virus.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.


COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) - ... 7b48e9ecf6

Journal reference:

Moitra, P., Alafeef, M., Dighe, K., Ray, P. et al. (2020). Rapid and Low-cost Sampling for Detection of Airborne SARS-CoV-2 in Dehumidifier Condensate. medRxiv. ... 20208785v1
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