health

Medical masks best, cotton good, bandanas worse: droplet study

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By SPENCER PLATT

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Health experts have determined that face coverings are a vital tool in reducing the spread of coronavirus 

Masks are important because some 30-40 percent of people who are infected may not show symptoms but still unwittingly spread the virus when they cough, sneeze or just talk.

We all now have the green light to wear masks in public air-con places. No excuses!!! Don't let Elvis down!!!

1 ( +2 / -1 )

Masks are important because some 30-40 percent of people who are infected may not show symptoms 

Amazing how you can be infected with corona and not show symptoms but if you have the flu, you're down and out.

-6 ( +1 / -7 )

Amazing how you can be infected with corona and not show symptoms but if you have the flu, you're down and out.

Well, if you "have the flu" obviously you are not including any asymptomatic cases, that is not amazing at all. people suffering from a disease are not asymptomatic by definition.

You can get infected with influenza virus and be completely asymptomatic, in some studies close to 30% of the people infected will not have symptoms. PMC4586318

4 ( +5 / -1 )

Stuck in a more-or-less socially distanced supermarket queue yesterday with both the guy behind me and the guy in front of me wearing bandanas (while I wore a surgical mask), it did actually occur to me to wonder how effective bandanas are, especially when the guy in front kept lowering his bandana beneath his chin in the apparent belief that it would help him to hear the checkout woman more easily.

Now I know. Not very effective at all.

2 ( +2 / -0 )

As I've been saying for a while, masks are just supposed to stop coughs and sneezes, and the quality of masks do matter.

Now, the conondrum of all of this is, asymptomatic people, by definition, have no symptoms, which means they are not going to be sneezing and coughing all the time, and I'm the rare occasion they do, sneeze etiquete should be for the most part more than enough to contain droplets.

In fact, even with masks people should engage in sneeze etiquette, since, like this study shows, droplets still fly away even with masks.

Also, even if droplet ammout is reduced in by up to 90% in cloth masks, infection studies have showed that they performed about as good or worse than not wearing a mask, which means that the remaining 10% of droplets is more than enough to generate transmission by droplets.

My worry, and that of many epidemiologists is not about droplets, but about infection dynamics and risks associated.

First, a mask will not protect anyone against infection for the most part, and most studies link SARS-CoV-2 infections to long interactions in closed spaces, making interfamily in-house interactions the main route of infection.

There is strong evidence that orofecal transmission is a mayor route for SARS-CoV-2, which cannot be prevented by a mask.

Second, there is evidence that people who use masks tend to not social distance, and even in cases forces people to get closer in order to hear a muffled voice, which can have a negative effect on transmission.

Third, not using a mask properly, using the same mask for a long time, constantly touching your face to adjust the mask, moisture accumulation in the mask among other factors can make infection more likely than not wearing a mask at all.

Forth, masks recommendations create stigmatization and discrimination for those with conditions that do not allow them to wear masks, who many times are forced to wear them anyway, putting their health at risk.

Fifth, mask recommendations have already created a problems in the supply of masks, which can translate into people who do require masks not being able to get them.

Because of these risks, and the fact that there is very low evidence that masks are working to prevent the most common routes of transmission, some epidemiologist are against blanket usage of masks by the wider population at all times when outside the home.

Most recommendations by epidemiologists involve very specific scenarios, like peak hour public transportation, in which the distance between people is so small that using all methods posible to avoid transmission could make sense, but once again, even for these scenarios, recommendations are based in theoretical prevention, and not in hard science that has proven the prevention.

-5 ( +1 / -6 )

Now, the conondrum of all of this is, asymptomatic people, by definition, have no symptoms, which means they are not going to be sneezing and coughing all the time, and I'm the rare occasion they do, sneeze etiquete should be for the most part more than enough to contain droplets.

That is not supported by any studies I have seen. Citation would be good.

In fact, even with masks people should engage in sneeze etiquette, since, like this study shows, droplets still fly away even with masks.

Which is no problem, it is not like you can only do one or the other, you can easily do both.

Also, even if droplet ammout is reduced in by up to 90% in cloth masks, infection studies have showed that they performed about as good or worse than not wearing a mask, which means that the remaining 10% of droplets is more than enough to generate transmission by droplets.

Citation for this. What is the ID50 for covid-19? how likely is that a reduction of exposure of 90% have no effect in transmission?

First, a mask will not protect anyone against infection for the most part, and most studies link SARS-CoV-2 infections to long interactions in closed spaces, making interfamily in-house interactions the main route of infection.

Citation needed for the first part, who demonstrated that a mask does not offer any kind of protection? I mean, absolutely nothing protects to a perfect 100%, but that is not the same as not being protective.

There is strong evidence that orofecal transmission is a mayor route for SARS-CoV-2, which cannot be prevented by a mask.

Citation for this would be very interesting, even recent articles only mention that this is considered just a possible route, not even confirmed, much less a "mayor" route.

Second, there is evidence that people who use masks tend to not social distance, and even in cases forces people to get closer in order to hear a muffled voice, which can have a negative effect on transmission.

It would be very interesting to see this evidence, seems like a very simple study to make, and even simpler thing to correct.

Third, not using a mask properly, using the same mask for a long time, constantly touching your face to adjust the mask, moisture accumulation in the mask among other factors can make infection more likely than not wearing a mask at all.

So masks are the same as every other preventive measure, from isolation to washing the hands, no surprise here, a perfect reason to educate people in the correct use, not so much to stop recommending doing it.

Forth, masks recommendations create stigmatization and discrimination for those with conditions that do not allow them to wear masks, who many times are forced to wear them anyway, putting their health at risk.

Anybody that actually would have any trouble by using a 3ply or cottong mask puts more their health at risk by being in any kind of situation where the mask is recommended. The actual recommendation would be not to be in that situation in the first place.

Fifth, mask recommendations have already created a problems in the supply of masks, which can translate into people who do require masks not being able to get them.

This should be solved by increasing the supply, there is absolutely nothing wrong with recommending something that is useful and have an effect. Bad would be to recommend something useless, since this is not the case the solution is to have more masks so they can can their intended effect everywhere they are needed.

Because of these risks, and the fact that there is very low evidence that masks are working to prevent the most common routes of transmission, some epidemiologist are against blanket usage of masks by the wider population at all times when outside the home.

Which epidemiologist? based on what data? how much of the discussion has been done about the obvious other solutions that solve the problems?

Most recommendations by epidemiologists involve very specific scenarios, like peak hour public transportation, in which the distance between people is so small that using all methods posible to avoid transmission could make sense, but once again, even for these scenarios, recommendations are based in theoretical prevention, and not in hard science that has proven the prevention.

Epidemiological evidence is also science, after all there is no "hard science" proving the quantitative effect of isolation or hand washing for the prevention of COVID-19 either? so according to you there is no point in recommending any measure.

5 ( +7 / -2 )

That is not supported by any studies I have seen. Citation would be good.

Which part? The part of asymptomatic people having no symptoms?

Sneeze etiquete stopping droplets? Because each one is kind of self evident.

Here are some recommendations on sneeze etiquete to prevent infections:

https://www.cdc.gov/healthywater/hygiene/etiquette/coughing_sneezing.html

https://www.uhs.nhs.uk/PatientsAndVisitors/Yourstayinhospital/Makingyourstaywithussafe/Preventinginfection/What-can-you-do-to-prevent-infection.aspx

https://www.longdom.org/open-access/knowledge-and-practice-of-sneeze-and-cough-etiquettes-among-participants-in-a-randomized-study-in-ekitistate-southwester.pdf

Which is no problem, it is not like you can only do one or the other, you can easily do both.

Never said it was a problem.

Citation for this. What is the ID50 for covid-19? how likely is that a reduction of exposure of 90% have no effect in transmission?

The ID50 of SARS-CoV-2 to cause COVID-19 is not known. But usually the ID50 of an infection is more dependent of the viral load of the individual, than the dosage of virus in each droplet.

What I'm saying is from the only available study into cloth masks as a way to stop an infection of ILI.

https://bmjopen.bmj.com/content/bmjopen/5/4/e006577.full.pdf

As said before, there is actually very little studies on the actual effectiveness of masks to stop infections, which for most of the questions you are asking the answer will be "we don't know".

Citation needed for the first part, who demonstrated that a mask does not offer any kind of protection? I mean, absolutely nothing protects to a perfect 100%, but that is not the same as not being protective.

Once again, studies are scarce in the mask front, but basically most randomized high evidence studies find that if there is any benefit on the wearer, it is only with high quality masks.

But there is actually a report from Norway’s Institute for Public Health that made calculations on the current COVID-19 pandemic, and how many infections it could prevent if we assume a 20% asymptomatics and a very large 40% risk reduction by wearing masks, and found out that you will require 200,000 people wearing one to prevent a single infection in a week.

https://www.fhi.no/globalassets/dokumenterfiler/rapporter/2020/should-individuals-in-the-community-without-respiratory-symptoms-wear-facemasks-to-reduce-the-spread-of-covid-19-report-2020.pdf

Citation for this would be very interesting, even recent articles only mention that this is considered just a possible route, not even confirmed, much less a "mayor" route.

https://www.cebm.net/wp-content/uploads/2020/07/SARS-CoV-2-and-the-Role-of-Orofecal-Transmission-Evidence-Brief-2.pdf

It would be very interesting to see this evidence, seems like a very simple study to make, and even simpler thing to correct.

https://journals.lww.com/ear-hearing/Abstract/9000/Covid_19_Lockdown_Affects_Hearing_Disability_and.98626.aspx

So masks are the same as every other preventive measure, from isolation to washing the hands, no surprise here, a perfect reason to educate people in the correct use, not so much to stop recommending doing it.

That wasn't the point I was trying to make.

Anybody that actually would have any trouble by using a 3ply or cottong mask puts more their health at risk by being in any kind of situation where the mask is recommended. The actual recommendation would be not to be in that situation in the first place.

Not really, There are many ailments that have negative consequences by wearing masks, and are not at all vulnerabilities against COVID-19.

One of those groups are those who have medication and behavior managed severe chronic migraines. I know at least of one case of someone like that who has suffered a lot because of the masks requirements, many times not being able to get out of his bed for days with vomiting after wearing a mask for an hour.

Your response is in fact the kind of problems I've seen on this, it is assumed that anyone with a real health problem isn't shouldn't be saying anything for one reason or another.

This should be solved by increasing the supply, there is absolutely nothing wrong with recommending something that is useful and have an effect.

Actually, there was already damage done because of this.

In the UK, people in care homes who had COVID-19 patients were unable to get access to any type of masks, because the government put them in the bottom of the list to get masks, and there were even stories of workers from care-homes asking to school children to make some cloth masks for them, out of desperation.

It is well known that the UK high death toll was in a big part because of there uncontrollable outbreaks in the care homes.

But hindsight is always 20/20 I guess.

Bad would be to recommend something useless, since this is not the case the solution is to have more masks so they can can their intended effect everywhere they are needed.

Not sure if you read the same article, but they basically said that bandanas are useless, and if I remember correctly there were recommendations in some countries of using them.

Which epidemiologist? based on what data? how much of the discussion has been done about the obvious other solutions that solve the problems?

Do you want me to list them all?

I would say, read the discussions and responses on articles like the ones from the BJM.

The people who I know who are "famous" and have been consistently warning about a blanket mask wearing by the wide population , or are critical of these policies are:

Tom Jefferson

Carl Heneghan

Anders Tegnel

Henning Bundgaard

Epidemiological evidence is also science, after all there is no "hard science" proving the quantitative effect of isolation or hand washing for the prevention of COVID-19 either? so according to you there is no point in recommending any measure.

It is not the same. I'm talking about high quality evidence studies against low quality evidence studies.

There is very high quality evidence for isolation, hand washing for the prevention of ILI. The evidence for face masks is extremely lacking.

There are very few mask studies, and most are not even randomized.

-2 ( +1 / -3 )

Sneeze etiquete stopping droplets? Because each one is kind of self evident.

No, it is not, you are complaining that there is no "hard science" to prove that masks are effective, that means that the alternative you are recommending does have that, right? Specifically when you say that "etiquette should be sufficient", the current consensus is that it is not. One thing is to recommend it above nothing, another completely different is to recommend it to replace also using masks.

Never said it was a problem.

Then there is no need to stop recommending or even requiring masks then.

The ID50 of SARS-CoV-2 to cause COVID-19 is not known. But usually the ID50 of an infection is more dependent of the viral load of the individual, than the dosage of virus in each droplet.

That is mistaken, we are talking about people here, not tissue cultures, the IC50 depends on the viral titers from the exposition for the individual, which is exactly why reducing the titers one full order of magnitude (or two) is a reason perfectly logical to make this exposure fail to reach a level enough for the infection.

What I'm saying is from the only available study into cloth masks as a way to stop an infection of ILI.

https://bmjopen.bmj.com/content/bmjopen/5/4/e006577.full.pdf

Your reference is irrelevant, it is not only about completely different pathogens, it does not show that wearing masks is worse than not wearing them, and even concludes "The data from this study providesome reassurance about medical masks, and are thefirstdata to show potential clinical efficacy of medical masks."

That is a completely different thing from "infection studies have showed that they performed about as good or worse than not wearing a mask" which is what you said.

As said before, there is actually very little studies on the actual effectiveness of masks to stop infections, which for most of the questions you are asking the answer will be "we don't know".

Which is precisely why I asked you for sources when you clearly said they don't, good to know you don't actually have the evidence to prove what you wrote.

Once again, studies are scarce in the mask front, but basically most randomized high evidence studies find that if there is any benefit on the wearer, it is only with high quality masks.

Not a single one for COVID-19, which is a very important part of your criticism, not having "hard science" to support the recommendation, if that is the case then you need it to reject the recommendation also.

But there is actually a report from Norway’s Institute for Public Health that made calculations on the current COVID-19 pandemic, and how many infections it could prevent if we assume a 20% asymptomatics and a very large 40% risk reduction by wearing masks, and found out that you will require 200,000 people wearing one to prevent a single infection in a week.

That is not a scientific report, its methodology is not open and their conclusions depend on unproven assumptions (a reduction of 40% of the transmission? based on what exactly?) it has not a single statistical calculation to even describe the confidence intervals. If that is what you use to sustain your opinion then you definitely cannot criticize anybody for not using experimental data as a source. Even the own authors put a lot of qualifiers on their conclusions because it is not something that can just blindly be used for other locations (and judging for the low scientific value of the report, not even in Norway).

https://www.cebm.net/wp-content/uploads/2020/07/SARS-CoV-2-and-the-Role-of-Orofecal-Transmission-Evidence-Brief-2.pdf

Exactly, in no place of this report it is reported the conclussion that orofecal transmission is a mayor route, only that it is possible and should be examined to see how important it is. That is another report you are misinterpreting.

https://journals.lww.com/ear-hearing/Abstract/9000/Covid_19_Lockdown_Affects_Hearing_Disability_and.98626.aspx

Did you confuse the study you wanted to reference? because this one says absolutely nothing about the wearing of mask making people converse in unsafe distances, It is not even a study about the regular population but on people with hearing disabilities.

This does absolutely nothing to support the point you wanted to make.

That wasn't the point I was trying to make.

No, that is because it is the point I am trying to make.

Not really, There are many ailments that have negative consequences by wearing masks, and are not at all vulnerabilities against COVID-19.

One of those groups are those who have medication and behavior managed severe chronic migraines. I know at least of one case of someone like that who has suffered a lot because of the masks requirements, many times not being able to get out of his bed for days with vomiting after wearing a mask for an hour.

That is still an example about people that should not be in a situation where a mask is recommended or required, in closed spaces and contact with many other people, not even for infection but for their condition.

And of course they can be completely free of risks and not using masks by using any of the many other mechanisms to avoid close social contact that are available.

Your response is in fact the kind of problems I've seen on this, it is assumed that anyone with a real health problem isn't shouldn't be saying anything for one reason or another.

Of course not, the real assumption is that being in close contact with other people without a mask is only one of the many options that are available to do things, so it is not at all an unavoidable situation.

> In the UK, people in care homes who had COVID-19 patients were unable to get access to any type of masks, because the government put them in the bottom of the list to get masks, and there were even stories of workers from care-homes asking to school children to make some cloth masks for them, out of desperation.

It is well known that the UK high death toll was in a big part because of there uncontrollable outbreaks in the care homes.

But hindsight is always 20/20 I guess.

Again, that is a problem not on the correct and effective use of ppe, but on the supply which is (was?) not adequate without a valid reason to justify it. People on hospitals did not have many other kinds of ppe without the excuse of general population using it. Once again, that is a very different problem.

Not sure if you read the same article, but they basically said that bandanas are useless, and if I remember correctly there were recommendations in some countries of using them.

My comment is in response of yours saying that medical mask would run out in hospitals because of the recommendation for the general population. Unless your argument is that hospitals were running out of bandanas it is still irrelevant.

Let me be more clear, recommending medical masks or N95 respirators to avoid spreading from asymptomatic people is not a problem, because it is very likely an effective measure. The problem would be if the masks were useless for this purpose and they would be wasted without benefit at the same time that availability is poor in the places were they would actually be useful.

The people who I know who are "famous" and have been consistently warning about a blanket mask wearing by the wide population , or are critical of these policies are:

Tom Jefferson

Carl Heneghan

Anders Tegnel

Henning Bundgaard

I cannot find any scientific opinions based on current knowledge, I can only find dated conclusions based on information we now know is false (rates of asymptomatic patients and transmission), asking for studies to clarify the situation but without a conclusion about it (it is not the same to say that we don't have data to prove efficacy than to say we have data to prove they are not effective), opinions about how bad it is to recommend exclusively using masks without any other measure (which is something nobody is doing, masks are always part of the full arsenal of measures) The last one is actually conducting a clinical trial to find out how effective they are. That is completely different from warning about their use.

It is not the same. I'm talking about high quality evidence studies against low quality evidence studies.There is very high quality evidence for isolation, hand washing for the prevention of ILI. The evidence for face masks is extremely lacking.

There are very few mask studies, and most are not even randomized.

For COVID-19? again, I would love to see those references, because measures are not universally effective against all infections equally. The whole point of recommending masks for this pandemic is the unexpectedly big role of asymptomatic and pre-symptomatic carriers have on the transmission. The lack of information also applies for their lack of efficacy, It is a cheap and easy measure, that complements a full repertoire of things normal people can do to prevent transmission, scientifically speaking we do not know that hand washing actually works or not for COVID-19, we strongly suspect it. But that is enough to recommend doing it, masks are the same.

Nothing is ever free of disadvantages, and nothing is absolutely protective, but saying that we should not recommend it because we don't have experimental data to prove their use is betting lives on the less likely possibility, it could be working, it is actually likely it is working, that is why professional associations that deal with infectious diseases and public health all around the world coincide in recommending it use.

If you think everybody is wrong then you can present data to contradict the current opinion and THEN it will have to change, but just saying that maybe everybody is wrong is not enough.

1 ( +2 / -1 )

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