Wie die Masken gegen die Pandemie wirken

Started by AribertDeckers, September 18, 2023, 06:54:39 PM

AribertDeckers

Wie die Masken gegen die Pandemie wirken? Meiner Vermutung nach ganz anders als überall behauptet wird.

Sehr hilfreich für meine Darstellung ist eine kürzlich veröffentlichte Studie, deren Pressemitteilung ich hier wiedergebe:


https://news.northwestern.edu/stories/2023/09/covid-patients-exhale-up-to-1000-copies-of-virus-per-minute-during-first-eight-days-of-symptoms/

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COVID patients breathe large amounts of virus early on

Northwestern investigators collect samples over the entire course of infection to determine when a person is most infectious

September 8, 2023 | By Marla Paul
COVID-19
Feinberg School of Medicine medicine

COVID patients exhale high numbers of virus during the first eight days after symptoms start, as high as 1,000 copies per minute, reports a new Northwestern Medicine study.

It is the first longitudinal, direct measure of the number of SARS-CoV-2 viral copies exhaled per minute over the course of the infection — from the first sign of symptoms until 20 days after.

On day eight, exhaled levels of virus drop steeply, down to near the limit of detection — an average of two copies exhaled per minute.

Northwestern investigators tested breath samples — collected multiple times daily from 44 individuals — over the entire course of infection to determine when a person is most infectious.

The study will be published in eLife and has been posted as a pre-print.

Mild and moderately symptomatic patients with COVID still exhale large amounts of virus, though severely symptomatic cases exhale higher levels on average, the study reports.

Vaccinated and unvaccinated patients exhale similar levels of virus over the course of infection, the research shows.

The amount of virus being exhaled while infected was the same no matter which variant a person was infected with — people infected with Alpha exhaled just as much as those infected with Omicron, the study reports.

"An important question in understanding transmission of SARS-CoV-2 is how much virus a patient is exhaling into the environment over the course of their infection and for how long," said senior author Christina Zelano, assistant professor of neurology at Northwestern University Feinberg School of Medicine. "During COVID-19 infection, at what point are you exhaling a lot of virus, and when do you stop breathing it out?"

"The vast majority of research on viral loads over the course of a COVID-19 infection has been based on nasal or oral swabs, which measure virus in the nose or throat," said lead study author Gregory Lane, senior research project manager in Zelano's lab. "However, SARS-CoV-2 is spread through breath, and virus on the breath may not match virus in the nose. The dynamics of viral shedding on breath over the course of infection are poorly understood, despite the fact that this is how the virus spreads."

Exhaled levels of the virus drop steeply by day eight, Northwestern Medicine investigators find

Also unknown is the relationship between levels of viral RNA on breath and symptom severity, vaccination status, virus variant and patient age and sex. To answer these questions, Zelano said, we needed a method to directly measure viral RNA on breath, repeatedly in the same patient over the course of their infection.

"We developed this easy, cheap method and used it to collect over 300 breath samples from 44 patients over the course of their infections — multiple samples a day over multiple days," Lane said.

With this new device, investigators detected viral RNA in 100% of specimens collected from COVID-positive patients who were within 10 days of symptom onset and in none of the specimens collected from COVID-19 negative patients — a very high rate of accuracy.

The study findings could be used to calculate the amount of time it takes for an individual to exhale an infectious dose of SARS-CoV-2, Lane.

"For example, if we assume the infectious dose for COVID is 300 copies, then a person who is exhaling 1,000 viral copies per minute would exhale an infectious dose in 20 seconds (highly risky in an elevator), whereas a person who is exhaling two viral copies per minute would exhale an infectious dose in about two hours (probably safe in an elevator)," Lane said. 

It is not yet known what an infectious dose of viral airborne particles is.

For the study, Northwestern scientists created and patented a portable, non-invasive, inexpensive device to collect breath samples from infected people, and used qPCR to measure SARS-CoV-2 in those samples. They used this device to test for the presence of the virus over 10 minutes of natural, relaxed breathing, establishing a conservative baseline of exhaled virus amount. Talking, singing or shouting would likely increase amounts of exhaled virus.

Scientists shipped the device to patients' homes, allowing them to self-collect samples from their own home, which were mailed back to the lab for analysis. They recruited patients testing for COVID-19 from Northwestern Medicine. Participants watched a video online to learn how to collect samples. Patients provided multiple samples per day over the entire course of infection.

Samples were mailed back to the lab, where qPCR was used to quantify numbers of viral RNA copies in breath specimens.

"Once you can answer the question of how many viruses you are exhaling for each day after your symptoms start, critical pieces of the puzzle of how to avoid the spread of COVID-19 fall into place," Lane said. "This information speaks directly to when someone with COVID-19 should isolate; when they are more likely to infect other people by breathing out virus into the air around them; and when they become much less likely to spread the infection. These two pieces of information are very important for infection control and for informing public health recommendations."

The study measured virus on breath from the first day symptoms start, which is day zero. From that day until day eight, infected people exhaled lots of virus, the scientists found. The amount varied, with peaks of 1,000 viral copies a minute, but the average was high. Then, on day eight, it dropped steeply to levels that hovered around the limit of detection (about two copies a minute), with few exceptions.

Because the device is scalable (the paper provides instructions to make it), it can be used for other respiratory diseases to obtain measurements to find out how much of a pathogen is on the breath.
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Wegen der Details - und überhaupt: Bitte die Originalmeldung lesen!

AribertDeckers

#1
Der staatliche japanische Fernsehsender NHK hat eine Web-Site, in der in Englisch für Zuschauer in der ganzen Welt aus Japan berichtet wird.

Diese Sendung vom 14. September 2023, gerade 5 Tage alt, ist über Honigbienen:


https://www3.nhk.or.jp/nhkworld/en/ondemand/video/2032296/

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Japanese Honeybees

Japanology Plus 28m 00s
Broadcast on September 14, 2023 Available until March 31, 2026
*First broadcast on September 14, 2023.

Japanese honeybees are wild, difficult to farm, and produce less honey than the Western honeybees used for most commercial honey production. But the multifloral honey they produce has a rich and complex flavor. Caring for Japanese honeybees brings hobbyist beekeepers closer to the profundity and unpredictability of nature. We learn about creative approaches to looking after Japanese honeybees, and about the surprising way they deal with predators.
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[*/quote*]



Im Februar 2021 brachte NHK einen Bericht über Tran Ngoc Phuc:


https://www3.nhk.or.jp/nhkworld/en/ondemand/video/2058734/

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Technology to Defeat the Coronavirus: Tran Ngoc Phuc / Chairman, Metran
Direct Talk 15m 00s
Broadcast on February 5, 2021 Available until February 5, 2022
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Leider ist dieser Bericht nicht mehr online. Dabei ist dieser Bericht extrem wichtig. Er berichtet zwar über die Beatmungsgeräte, die Tran Ngoc Phuc entwickelt und herstellt, aber er zeigt vor allem eines: Computer-Simulationen mit den Luftströmungen bei Masken.

Genau darum geht es: um die Luftströmungen.


Es gibt eine Reihe von Videos, auch bei YouTube, in denen mit Rauch gezeigt wird, wie sich die Luft beim Ausatmen bewegt. Kurz gesagt: beim direkten Ausatmen gibt es einen Luftstrahl. Eine Maske jedoch bewirkt eine großflächige Verteilung, und - je nach Konstruktion - vor allem eine Ausbreitung NICHT als direkten Strahl nach vorne, sondern als eine große Wolke, bei einfachen Masken nach hinten, und eben nicht dem Anderen ins Gesicht.

Beim Einatmen gibt es die gegenteilige Aktion: anstatt einen direkten kleinen Durchmesser der angesaugten Luft zu haben, wirkt bei einer Maske deren gesamte Oberfläche, so daß es eine GROSSE Fläche ist, durch die die Luft eingesagt wird.

Wir haben es also ZWEI MAL mit einer Verdünnung der Partikel in der Luft zu tun: einmal beim Einatmen, einmal bei Ausatmen.


In einigen Berichten über Masken heißt es, die Filterwirkung auf die Partikel würde über Elektrostatik wirken. Aber das halte ich für einen groben Fehler. Spätestens nach mehreren Minuten ist eine Maske durch das Ausatmen der feuchten Atemluft so benetzt,daß jegliche elektrischen Aufladungen abgeleitet sind.

AribertDeckers

Noch relativ am Anfang der Pandemie - und für mich leider nicht mehr auffindbar - gab es elektronenmikroskopische Aufnahmen der Schäden, die SarsCoV2 in einer Schleimhaut anrichtet. Es sieht aus wie nach einem Bombenangriff: ein Bombentrichter neben dem anderen.

Eine wichtige Erkenntnis war schon relativ früh: daß die Zahl der Viren pro Quadratzentimeter Schleimhaut eine große Rolle spielt. Vereinzelte Viren kann die Schleimhaut verkraften und überstehen. Wird die Zahl zu groß, bricht die Abwehr der Schleimhaut zusammen.

Dieser Zusammenhang Partikeldichte der einfallenden Viren pro Flächeneinheit ist extrem wichtig. Er entscheidet, ob der Mensch den Angriff gut übersteht oder stark erkrankt.

Die Frage war damit schon am Anfang: wieviele Viren kommen durch die Luft in die Atemorgane?

Durch die Studie von Northwestern gibt es jetzt gute Anhaltspunkte

"COVID patients exhale high numbers of virus during the first eight days after symptoms start, as high as 1,000 copies per minute, reports a new Northwestern Medicine study."
 
Es sind also nicht Myriaden, sondern relativ wenige. Da spielt die Verdünnung der Luft eine sehr wesentliche Rolle. Bei einer höheren Virenbelastung gäbe es zwar auch eine Verdünnung, aber die Schleimhaut - auf der anderen Seite - wäre mit der hohen Zahl der Viren überlastet. Diese neuen Zahlen zeigen, warum die Schleimhaut es bei wenigen Treffern schafft, mit Viren fertig zu werden: weil es nicht so viele sind!

Die Studie zeigt aber auch eines: bei längerer Belastung nützt die Verdünnung durch die Maske weniger, weil die GESAMTE ATEMLUFT stark mit Viren angereichert ist. Das bedeutet vor allem eines: LÜFTEN, LÜFTEN, LÜFTEN!

AribertDeckers

#3
This is a translation of a part of text above. http://www.journalist.is/folia/index.php?topic=17.msg57#msg57
Translated with DeepL.com (free version)


The Japanese state broadcaster NHK has a website that reports from Japan in English for viewers around the world.

In February 2021, NHK published a report about Tran Ngoc Phuc:

https://www3.nhk.or.jp/nhkworld/en/ondemand/video/2058734/

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Technology to Defeat the Coronavirus: Tran Ngoc Phuc / Chairman, Metran
Direct Talk 15m 00s
Broadcast on February 5, 2021 Available until February 5, 2022
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Unfortunately, this report is no longer online. Yet this report is extremely important. Although it reports on the ventilators that Tran Ngoc Phuc develops and manufactures, it shows one thing above all: computer simulations with the air flows in masks.

And that's exactly what it's all about: airflow.


There are a number of videos, including on YouTube, in which smoke is used to show how the air moves when you exhale. In short: when you breathe out directly, there is a jet of air. A mask, however, causes a large-area distribution and - depending on the design - above all a spread NOT as a direct jet forwards, but as a large cloud, in the case of simple masks backwards, and not into the other person's face.

When inhaling, there is the opposite action: instead of having a direct small diameter of the inhaled air, the entire surface of a mask acts so that it is a LARGE surface through which the air is inhaled.

So we are dealing with a dilution of the particles in the air TWICE: once when breathing in, once when breathing out.



Some reports on masks claim that the filtering effect on the particles works via electrostatics. But I think this is a gross error. After several minutes at the latest, a mask is so wetted by exhaling moist breathing air that any electrical charges are dissipated.


In this picture you see the air stream with particles. A mask prevents this.


https://pbs.twimg.com/media/GTRYXWcaYAM-gbZ?format=png&name=900x900

AribertDeckers

#4
26.12.2024
Wieviele Partikel reichen für eine Infektion?

Die bereits gestellte Frage nach der Zahl der für eine Infektion notwendigen Partikel könnte durch eine Reihe von Studien einigermaßen beantwortet sein. Vor einigen Tagen hat David Lingenfelter eine Studie erwähnt:


https://x.com/dlingenfelter/status/1865109827233706341

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David Lingenfelter, PhD @dlingenfelter

The infective dose of SARS-CoV-2 in humans is around 100 particles.

Higher doses at exposure correlate with higher viral loads and severe symptoms in animals.

This suggests that the more virus you are exposed to the more severe your disease.

https://cambridge.org/core/journals/epidemiology-and-infection/article/review-of-infective-dose-routes-of-transmission-and-outcome-of-covid19-caused-by-the-sarscov2-comparison-with-other-respiratory-viruses/8607769D2983FE35F15CCC328AB8289D
Understanding COVID-19: Infective Dose, Transmission Routes, and Outcomes (essay)



8:03 PM · Dec 6, 2024
33.5K Views
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Zitat aus der Studie:

https://www.cambridge.org/core/journals/epidemiology-and-infection/article/review-of-infective-dose-routes-of-transmission-and-outcome-of-covid19-caused-by-the-sarscov2-comparison-with-other-respiratory-viruses/8607769D2983FE35F15CCC328AB8289D#

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Review of infective dose, routes of transmission and outcome of COVID-19 caused by the SARS-COV-2: comparison with other respiratory viruses

Published online by Cambridge University Press:  14 April 2021
Sedighe Karimzadeh
Open the ORCID record for Sedighe Karimzadeh,Raj Bhopal and Nguyen Tien Huy

Sedighe Karimzadeh*
    Affiliation:
    School of Medicine, Sabzevar University of Medical Sciences, Sabzevar, Iran
Raj Bhopal*
    Affiliation:
    Usher Institute, University of Edinburgh, EdinburghEH3 9AG, UK
Nguyen Tien Huy
    Affiliation:
    School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
*
    Author for correspondence: Sedighe Karimzadeh, E-mail: sediqekarimzadeh@gmail.com, Raj Bhopal, E-mail: Raj.Bhopal@ed.ac.uk
    Author for correspondence: Sedighe Karimzadeh, E-mail: sediqekarimzadeh@gmail.com, Raj Bhopal, E-mail: Raj.Bhopal@ed.ac.uk

Rights & Permissions [Opens in a new window]

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is pandemic. Prevention and control strategies require an improved understanding of SARS-CoV-2 dynamics. We did a rapid review of the literature on SARS-CoV-2 viral dynamics with a focus on infective dose. We sought comparisons of SARS-CoV-2 with other respiratory viruses including SARS-CoV-1 and Middle East respiratory syndrome coronavirus. We examined laboratory animal and human studies. The literature on infective dose, transmission and routes of exposure was limited specially in humans, and varying endpoints were used for measurement of infection. Despite variability in animal studies, there was some evidence that increased dose at exposure correlated with higher viral load clinically, and severe symptoms. Higher viral load measures did not reflect coronavirus disease 2019 severity. Aerosol transmission seemed to raise the risk of more severe respiratory complications in animals. An accurate quantitative estimate of the infective dose of SARS-CoV-2 in humans is not currently feasible and needs further research. Our review suggests that it is small, perhaps about 100 particles. Further work is also required on the relationship between routes of transmission, infective dose, co-infection and outcomes.
[...]
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100 Partikel, das ist eine sehr kleine Zahl!

Allerdings sind das nur grobe Schätzungen und eine Frage ist, was bei 50 Partikeln geschieht. Es gibt ja keinen Schalter, der bei 100 umgelegt ist und man erkrankt - und bei 99 nicht. Es muß also auch bei den Zahlen unter 100 etwas geschehen. Aber was? Gibt es dann flächige Infektionen, die einen Teil der Schleimhautoberfläche zerstören? Und was geschieht dann? Kann es sein, daß es Infektionen gibt, die schlicht und einfach nicht auffallen, weil es zu wenige Partikel sind, die aber trotzdem im Körper Schäden anrichten und eventuell sogar im Körper bleiben können?

Wir wissen es nicht. Aber wir wissen, daß schon eine sehr geringe Dichte von Viren in der Luft eine Infektion auslösen kann. Wir müssen also sehr vorsichtig sein und uns vor den Partikeln schützen, wenn wir überleben wollen.