COVID COVID-19 Coronavirus Containment Efforts

[OmCheeto]

...politicians need to make decisions with what they know

My governor has put her faith in the Harvard's Global Health Institute's recommendations. I just wish I could understand how they get their numbers. Specifically, the "target tests per 100k". Has anyone else tried to figure this out?

 

[vela]

I remember hearing Dr. Fauci insisting that there was virtually no threat from this virus. Don't stop travel. Don't stay home. Then stop travel. Then stay home. But it's harmful to wear masks. Then it's good to wear masks...

What's your point? Recommendations change as information is learned and the situation evolves.

 

[OmCheeto]

What's your point? Recommendations change as information is learned and the situation evolves.

Snopes says that was from a Feb 29 interview, when 1 person had died so far in the US, in case anyone is interested in what Dr. Fauci actually said, without having to rely on their memories.

 

[Evo]

Hi. Wife is buying these masks from Lazada. Do you think PM2.5 masks protect against Covid-19?

3 layers with respirators View attachment 262366View attachment 262367View attachment 262368

5 layers with respirators

View attachment 262369View attachment 262370

I would greatly appreciate any response. Thank you.

You shouldn't use masks with valves.

Some of these respirators have valves that allow exhaled air to get out, making it easier for the user to breathe. However, the downside of this is that other people are susceptible to the particles and pathogens that are exhaled through these valves.

https://www.healthline.com/health/best-face-mask-2#materials

Sorry, I had read this in a better medical site previously, but don't have the link now.

 

[PAllen]

Since this is a physics site, I’ll make a basic physics point that applies to all masks that I have seen or tried (I don’t know if it applies to N95, as I have never examined one. It definitely applies to surgical masks).

This is triggered by @Evo ’s comment, but generalizes it. Almost all sources keep saying masks are better protection for others than the wearer. I wish this were so, but I argue that this is absurd for a simple physical reason I have demonstrated on about 8 different masks. That is, that inhalation creates negative pressure that helps seal the mask around your face, giving close to the best filtration possible by whatever the mask material. In contrast, exhalation creates positive pressure that opens the mask face boundary, leading significantly more air to bypass filtration than on inhale. I have verified this for even tightly fitted professionally made masks. Unless the mask has an actual sealing agent, I don’t believe there is any way around this.

Thus, contrary to the common wisdom, you get most of filtration possible on inhale, and much less on exhale, so it is less effective at protecting others than you. Of course, everyone wearing masks mitigates this.

 

[anorlunda]

Almost all sources keep saying masks are better protection for others than the wearer.

It is not exhalation that is the problem, it is the cloud of droplets spread by a cough or a sneeze. That's how masks protect other people.

 

[PAllen]

It is not exhalation that is the problem, it is the cloud of droplets spread by a cough or a sneeze. That's how masks protect other people.View attachment 262524

But some of the sneeze droplets would get out the mask face boundary unfiltered, especially because positive pressure during a sneeze is much higher than an ordinary exhale. Conversely, sneeze droplets by someone else would be captured more effectively by you inhaling through a mask. My point still stands that basic physics of pressure without an airtight seal suggests the opposite of the common claims of effectiveness of masks.

In effect, they all have valves on exhale.

Just to be clear, I am in no way claiming that you wearing a mask doesn’t protect others. What I am disputing is the claim they protect others better than they protect you.

 

[atyy]

Since this is a physics site, I’ll make a basic physics point that applies to all masks that I have seen or tried (I don’t know if it applies to N95, as I have never examined one. It definitely applies to surgical masks).

This is triggered by @Evo ’s comment, but generalizes it. Almost all sources keep saying masks are better protection for others than the wearer. I wish this were so, but I argue that this is absurd for a simple physical reason I have demonstrated on about 8 different masks. That is, that inhalation creates negative pressure that helps seal the mask around your face, giving close to the best filtration possible by whatever the mask material. In contrast, exhalation creates positive pressure that opens the mask face boundary, leading significantly more air to bypass filtration than on inhale. I have verified this for even tightly fitted professionally made masks. Unless the mask has an actual sealing agent, I don’t believe there is any way around this.

Thus, contrary to the common wisdom, you get most of filtration possible on inhale, and much less on exhale, so it is less effective at protecting others than you. Of course, everyone wearing masks mitigates this.

In another thread, some evidence was posted against the effectiveness of masks as protecting others. However it did not rule out that masks protect others from the wearer in some other reasonable ways, merely in the way that was tested.

https://annals.org/aim/fullarticle/2764367/effectiveness-surgical-cotton-masks-blocking-sars-cov-2-controlled-comparison
Effectiveness of Surgical and Cotton Masks in Blocking SARS–CoV-2: A Controlled Comparison in 4 Patients
Seongman Bae, MD *; Min-Chul Kim, MD *; Ji Yeun Kim, PhD *; Hye-Hee Cha, BS; Joon Seo Lim, PhD; Jiwon Jung, MD; Min-Jae Kim, MD; Dong Kyu Oh, MD; Mi-Kyung Lee, MD; Seong-Ho Choi, MD; Minki Sung, PhD; Sang-Bum Hong, MD; Jin-Won Chung, MD; Sung-Han Kim, MD

 

[PAllen]

I should say the main test method I used is a chilled slide held in various positions near a mask on exhale. An inch front of the mask produced no fogging, while positions near the mask boundary produce a lot.

 

[atyy]

It is not exhalation that is the problem, it is the cloud of droplets spread by a cough or a sneeze. That's how masks protect other people.

Actually, depending on how the policy is sold, it may be exhalation that is the problem being considered.

If one is coughing or sneezing, one should simply self-isolate, then the question of mask to protect others does not even come into play.

In some cases, the mask is said to protect others because of the possibility of pre-symptomatic or asymptomatic transmission (eg. between barber and customer getting a haircut, both of whom feel well, and who need to be in non-transient close contact), which would mean transmission by normal conversation or exhalation.

Edit: I should say some asymptomatic people do cough (definition of 'asymptomatic' is variable) - they have chronic cough, and don't notice anything markedly different from normal. https://www.nejm.org/doi/full/10.1056/NEJMoa2008457

 

[anorlunda]

This thread is so long that it is nearly impossible to search. Early in this thread there were posts about peer reviewed papers from Singapore that showed the effectiveness of simple masks for the public.

I also suspect that we're talking past each other regarding the words "protect" and "effective". As I see it, the goal is to slow the spread among a public that is already practicing social distancing. We need to reduce the number of droplets projected 2 meters at face level for people passing each other on the sidewalk or talking with each other.

As I see it, even a 10% reduction in spread makes it worth while to use the masks. A 50% reduction would be wonderful. But to many people the words "protect" and "effective" would not apply below 95%.

 

[Astronuc]

Reuters reports a new round of n-coronavirus infections in Wuhan.

BEIJING (Reuters) - Wuhan, the epicentre of the novel Coronavirus outbreak in China, reported on Monday its first cluster of infections since a lockdown on the city was lifted a month ago, stoking concerns of a wider resurgence of the disease.

Wuhan reported five new confirmed cases, all from the same residential compound. One was the wife of an 89-year-old patient reported a day earlier in the first confirmed case in the central city in more than a month.

Apparently, there is also an increase in new cases in Germany.

 

[PeroK]

Apparently, there is also an increase in new cases in Germany.

Not according to this:

https://www.worldometers.info/coronavirus/country/germany/

Note that most countries figures appear to follow a weekly reporting cycle with usually a dip for two days every week.

If you average out on a weekly basis, the German figures have been steadily declining since late March.

PS this is not the case in the UK, where new cases have averaged about 5,000 per day steadily since early April:

https://www.worldometers.info/coronavirus/country/uk

 

[bob012345]

This thread is so long that it is nearly impossible to search. Early in this thread there were posts about peer reviewed papers from Singapore that showed the effectiveness of simple masks for the public.

I also suspect that we're talking past each other regarding the words "protect" and "effective". As I see it, the goal is to slow the spread among a public that is already practicing social distancing. We need to reduce the number of droplets projected 2 meters at face level for people passing each other on the sidewalk or talking with each other.

As I see it, even a 10% reduction in spread makes it worth while to use the masks. A 50% reduction would be wonderful. But to many people the words "protect" and "effective" would not apply below 95%.

It looks like much of what is happening in this video is just heat. It's not clear to me that most of what is projected isn't just air and CO2 when breathing. Droplet ejecta during a cough or sneeze is different. I don't think temporary exposure of a few seconds to air casually breathed out by a Covid positive person is enough to infect a person. Dr. Birx said it requires a few minutes exposure at close range such as in a conversations. Does anyone know for sure?

 

[Astronuc]

Not according to this:

https://www.worldometers.info/coronavirus/country/germany/

Note that most countries figures appear to follow a weekly reporting cycle with usually a dip for two days every week.

If you average out on a weekly basis, the German figures have been steadily declining since late March.

I was referring to an observation by the Robert Koch Institute. They track a reproduction number ratio of persons being infected by an individual (on average). According to CNN:

. . . its [Germany's] reproduction number has increased to above one for the past two days in a row, according to its center for disease control, the Robert Koch Institute (RKI). This means that one infected person is on average infecting more than one other person.

https://www.cnn.com/2020/05/11/asia/china-south-korea-coronavirus-reopening-intl-hnk/index.html

BBC - https://www.bbc.com/news/world-europe-52604676

Of course, in such systems, there is some noise.

 

[PeroK]

I was referring to an observation by the Robert Koch Institute. They track a reproduction number ratio of persons being infected by an individual (on average). According to CNN: https://www.cnn.com/2020/05/11/asia/china-south-korea-coronavirus-reopening-intl-hnk/index.html

BBC - https://www.bbc.com/news/world-europe-52604676

Of course, in such systems, there is some noise.

Two days is nonsensical. Anyone who looks at the figures can see the daily fluctuations. Also, the Germans have reached such a low level of new cases now that fluctuations or delays in reporting may look numerically significant.

In the last week Germany has recorded only 6,000 new cases. The UK gets that almost every day.

 

[kolleamm]

This might be a dumb question, but wouldn't it be better if the low risk people can return back to work while the people who are at high risk stay home and continue to receive benefits from the government?

 

[mfb]

But some of the sneeze droplets would get out the mask face boundary unfiltered, especially because positive pressure during a sneeze is much higher than an ordinary exhale. Conversely, sneeze droplets by someone else would be captured more effectively by you inhaling through a mask. My point still stands that basic physics of pressure without an airtight seal suggests the opposite of the common claims of effectiveness of masks.

Droplets are heavier than air and stick to surfaces they touch. They are less likely to follow the path of the air.

The masks do nothing against viruses that fly around on their own, and while they might prevent direct inhalation of droplets they can't prevent these droplets sticking to the mask.

I remember hearing Dr. Fauci insisting that there was virtually no threat from this virus. Don't stop travel. Don't stay home. Then stop travel. Then stay home. But it's harmful to wear masks. Then it's good to wear masks...

Then maybe you should check what he actually said, and if you maybe removed so much context that you changed the statement completely.

----

Some reports about German numbers are so stupid. "They went up the last three days!" - yes, that's the weekly pattern. It is usually followed by a new all-time low the next day (since the peak). Averaged over a week the numbers go down continuously.

 

[atyy]

This thread is so long that it is nearly impossible to search. Early in this thread there were posts about peer reviewed papers from Singapore that showed the effectiveness of simple masks for the public.

I don't remember such a paper, I think it was about surgical masks versus N95 masks in a procedure that generated aerosols.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081171/
"In the situation we describe, 85% of health care workers were exposed during an aerosol-generating procedure exposed while wearing a surgical mask, and the remainder were wearing N95 masks. That none of the health care workers in this situation acquired infection suggests that surgical masks, hand hygiene, and other standard procedures protected them from being infected. Our observation is consistent with previous studies that have been unable to show that N95 masks were superior to surgical masks for preventing influenza infection in health care workers (5). We emphasize, however, that nearly all experts recommend that health care workers wear an N95 mask or equivalent equipment while performing an aerosol-generating procedure. "

 

[atyy]

I don't think temporary exposure of a few seconds to air casually breathed out by a Covid positive person is enough to infect a person. Dr. Birx said it requires a few minutes exposure at close range such as in a conversations. Does anyone know for sure?

It is not known for sure, and a matter of probabilities. These reasonable estimates probably come from knowing the whereabouts of confirmed cases and knowing where they went and their close contacts, and whether they transmitted the virus to the people they encountered.

 

[OmCheeto]

Two days is nonsensical. Anyone who looks at the figures can see the daily fluctuations. Also, the Germans have reached such a low level of new cases now that fluctuations or delays in reporting may look numerically significant.

In the last week Germany has recorded only 6,000 new cases. The UK gets that almost every day.

Ouch. I wish you hadn't mentioned the UK.
It's kind of embarrassing how comparatively bad things look in the UK, when looking at the graphs. I think you are still behind in reported total cases by a factor of about 3.
So rising case counts is somewhat meaningless at the moment. From my eyeballing, you should have around 750,000 cases, versus the current 210,000.

Germany, with 7 day averaging, looks quite good.

I'm not sure why RKI uses only a 4 day average. With 7 day fluctuations, it seems like that would generate some nasty graphical harmonics.

RKI; "The number of incident cases estimated using the nowcasting approach is presented as a moving 4-day average to compensate for random effects of individual days (Fig. 5)."​

They do have reasonable cautions though about the R0 number, IMHO.

hmmm... This is odd. They don't have a "Fig. 5" on that document.

 

[mfb]

Iceland had no cases in the last 4 days and only 3 cases in all of May. Total active cases are down to 18.

 

[PAllen]

Any cases in Antarctica? Apparently not. Let’s meet up there. We’ll fix that.

 

[mfb]

Still no known cases there. Mainly scientists who try to stay isolated from the rest of the world.
https://en.wikipedia.org/wiki/COVID-19_pandemic_in_Antarctica
A few island countries avoided cases, too: Here is a list. I don't believe the claims of North Korea and Turkmenistan to have no cases, and I suspect Lesotho just doesn't have the organization to confirm cases.

 

[bhobba]

Dr. Birx said it requires a few minutes exposure at close range such as in a conversations. Does anyone know for sure?

Our hotline here in Australia says 15 minutes close contact is required. We do a huge amount of testing here in Aus so I think that is based on a lot of evidence. That means breaking the 1.5 meter distancing rule to pick up a Pizza or something like that is fine. I do it without any worries and I am in a very high risk group.

Thanks
Bill

 

[PeroK]

Ouch. I wish you hadn't mentioned the UK.
It's kind of embarrassing how comparatively bad things look in the UK, when looking at the graphs. I think you are still behind in reported total cases by a factor of about 3.
So rising case counts is somewhat meaningless at the moment. From my eyeballing, you should have around 750,000 cases, versus the current 210,000.

Here are the figures, taken from the worlometers website. This gives the average number of daily deaths for each week since the week ending 7 April. These are the five largest (and roughly comparable) European countries and the USA:

	USA	UK	Spain	Italy	France	Germany
07-Apr​	1,474​	624​	797​	671​	972​	177​
14-Apr​	2,068​	850​	601​	563​	772​	211​
21-Apr​	2,213​	747​	432​	512​	724​	227​
28-Apr​	1,962​	620​	363​	387​	409​	175​
05-May​	1,858​	589​	256​	279​	267​	117​
12-May​	1,587​	440​	189​	237​	185​	88​

There is a clear pattern here of steady decline for the past month, with the UK about 2-3 weeks behind Spain and Italy.

 

[morrobay]

Our hotline here in Australia says 15 minutes close contact is required. We do a huge amount of testing here in Aus so I think that is based on a lot of evidence. That means breaking the 1.5 meter distancing rule to pick up a Pizza or something like that is fine. I do it without any worries and I am in a very high risk group.

Thanks
Bill

Thanks for the information (at last) that quantifies exposures that can result in infections. Can you link the original source, that the hotline referenced ?

 

[bhobba]

Thanks for the information (at last) that quantifies exposures that can result in infections. Can you link the original source, that the hotline referenced ?

I simply rang our Hotline:
https://www.health.gov.au/contacts/national-coronavirus-helpline

Here is some written information from our newly released tracing app:
https://www.health.gov.au/sites/default/files/documents/2020/04/covidsafe-app-faqs-coronavirus-contact-app-covidsafe-faqs.pdf
'Who is a “close contact” for notification purposes? State and Territory public health officials will have the contact information for other users who have been within approximately 1.5 metres of the infected user for 15 minutes or more.'

Thanks
Bill

 

[mfb]

If that's needed for transmission, then I wonder why the disease is still around.

 

[bhobba]

If that's needed for transmission, then I wonder why the disease is still around.

Its not the only way of course eg if you touch something someone sneezed or coughed on (ever sneeze into your elbow - I have - you have to be fast - then yuck - coughing is not as bad), then touch your face without washing your hands first. Or if you sneeze or cough not into your elbow, it travels, I read - get this - up to 6 meters, so 1.5 meters is not foolproof. But you have to be unlucky if you only go out if necessary, wash your hands, social distance, only breaking, if you must, the 1.5 meter rule for under 15 minutes . As I said I am in a high risk group and I feel safe doing that.

As I said we do a lot of tracing here in Aus and it is only a small number we can't trace. That is expected to reduce even further with the new tracing app. For what it's worth I am not a tracing app fan - simply do what other countries do - use Google, credit card data, etc that is already kept. The psychology on it seems strange - the data is kept, but even in an emergency like this you can't use it - you need to voluntarily download an app.

Thanks
Bill