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What You Need to Know about Facemasks to Reduce Exposure and Transmission of the SARS-CoV-2 Virus

Uncategorized Jul 29, 2020

Hello there, my name's Dr. Cameron Jones from Biological Health Services. Thanks for joining me on another live stream. And we are continuing our investigation into various different aspects of the SARS-CoV-2 virus pandemic. And this week, one of the things that I want to get into is this issue of face masks. It seems to be a topic on everyone's lips, certainly.

And certainly, if you're in Melbourne, Victoria, Australia, face masks are mandatory now when we go out into the public. And there are a number of reasons for that. Now, there's been a lot that has been discussed in the mainstream media and in social media. I wanted to bring a different set of pieces of information to the table this week as it were.

And the reason for that is that there is appearing to be really, in a sense, a bit of confusion about whether face masks are good or aren't good, whether or not there will or won't be fines. Certainly, in my own neighborhood, I'm seeing a lot of compliance with face mask-wearing. But similarly, when I went out earlier today, I noticed that a lot of people were wearing no face masks and plastic visors.

So I want to talk about some of the research about this, and we're going to be focusing on some of the stats and facts and figures which I think are important for you to be aware of. So what I'm going to do now is I'm going to focus on things that we do know. Well, obviously the whole point of wearing a face mask is to minimize the infectious droplets.

And unless you haven't opened social media or read a newspaper, listened to the radio, or turned on the TV in the last six months, all of you, I think, would be familiar with the fact that the dominant transmission pathway is infectious droplets. But the big issue here is it's not just person to person transmission. It is the liberation of these infectious droplets, which then can dry as a dry aerosol.

And in a sense, they become like normal particulate matter and they can be distributed long distances and maintain their replication competence for some period of time. And again, there are some wonderful publications which I'm putting in the references to this live stream. They'll also be in the podcast and I encourage all of you to download what are, in many cases, free resources to educate yourself and allow you to share these with friends, family, and colleagues, and work people as well.

Now, what can history tell us about mask-wearing? Well, it can tell us quite a lot. Back in 1918, the Spanish flu, mask-wearing, in a sense, was mandated. And if you didn't wear a mask, there was advocation for sending people to jail. Now, the same type of response is occurring today in 2020. And certainly, in Victoria, noncompliance with wearing masks will certainly set you up for a fine, at minimum.

And certainly even today with a small rally, the Black Lives Matter rally in Sydney. I understand that before the rally even began, a number of individuals were fined for non-compliance with mask-wearing. So this issue of policy being used to make sure that the public is maintaining masks is really, really important. So they're using fines to establish this.

I want to discuss what we know about why masks work, which masks are potentially better than others, and a lot of the controversy that I see emerging on social media regarding mask-wearing and advocates for and against this. So, did it work in 1918? Well, to a great or a lesser extent, there was a lot of academic and public health work, very good work that emerged after the Spanish flu epidemic.

And what they were able to conclude afterward is that, in many cases, the wearing of masks did not work. I don't want you to switch off now because I am a firm believer in the importance of masks. But back in the Spanish flu epidemic, often people wore masks for long periods of time. There was very poor compliance. The compliance rate with actually wearing the mask was very low.

People wore the mask until they were absolutely filthy and very dirty. And of course, that is a contrary indication for mask-wearing. And so there are now directions for proper and appropriate mask-wearing and hygiene and disinfection and single-use disposable masks as well. So the conclusion was that, in a sense, mask-wearing compliance was very poor in the Spanish flu epidemic.

And that was why the conclusion was that this was not a proactive health message because people just didn't follow the rules very well. And also the other key thing is that the other way you can come into contact with the virus is, of course, through this T zone, your mucus membranes. So a mask is not going to protect your eyes.

And that's often why you will see people wearing plastic face shields when they are doing medical procedures or in close contact with groups of people who are very possibly contaminated, symptomatic or presymptomatic with the SARS-CoV-2 virus. Now, will it work in 2020 and beyond? Well, that's what all of us need to know and need to consider.

Well, what do we know now? Well, if you, like me, were getting confused. I needed to deep dive into the literature and review a lot of the public health messaging that I was hearing with what I was reading in the academic and peer-reviewed and open-source literatures regarding mask-wearing. What do you buy? You're probably all wondering that or have wondered that in the last couple of weeks.

Do you buy a medical-grade mask, if you can get it? Do you buy one with a vent or no vent? What are the pros and cons of this? Or do you use a special designer mask like the one from Bondi Air Co, which I love wearing? But that has a PM 2.5 filter in it and it has five different ways of filtering the user. Or do you use some mask available from a safety store, like I'm using here?

In any case, there's a lot of confusion, in a sense. But I need to remind you why this is important before we deep dive into some of the literature surrounding the pros and cons of different masks in specific reference to protecting you from getting the SARS-CoV-2 virus and then going on to have the illness of COVID-19.

And to do that, I'm going to play a quick little video, which is focusing on a laser light-scattering experiment which demonstrates the ability of a mask to prevent exposure and the liberation of these virus lighted particles into the air space, which can then be distributed elsewhere. To do that, I'm going to play a quick little video.

Now I'm recording.

Stay healthy.


Stay healthy.

Great. Less loud.

Stay healthy.


Are you recording?


Stay healthy.


Stay healthy.


Stay healthy.


So you can see with that laser light-scattering experiment, which allows you to visualize the aerosolization of the droplets into the air space. That the mask provides definite protection and there is a limitation of the aerosolization. But there is still confusion and differences of opinion. And I found myself right in the middle of a difference of opinion the other night when I was on Twitter and I saw a post by the chief health officer.

The Chief Health Officer was making a point regarding valved masks. These are valved masks like this and you can see that there's a valve inside. The benefit of a valved mask, certainly for people who wear glasses like me, is that there is an exhalation valve. So it is easy to breathe and it doesn't build up so much condensation, which can interfere with your line of sight.

However, what the Chief Health Officer was saying was that the valved mask allows virus particles to be liberated. And I had just recently read a paper, in fact, the day before, that was talking about a whole range of different masks. And in fact, the valved masks came out on top. So I'm going to review that paper to put that question in context, and then I'm going to answer the question certainly with other additional research that I'm going to talk about later in this live stream.

Now, valves or no valves on masks. Well, a paper from July 21, which appeared in, talking about bioaerosols. Now, bioaerosols are usually those bacteria, yeast, and fungus that can be emitted by an ill person. But more specifically, in context today, we're talking about virus particles, which can be expelled often from a sneeze with mucus or whilst talking or singing or doing any type of verbalization.

The key question in this publication is: how far can these particles be transmitted? And face mask efficiency depends on four factors: the material that the face mask is made of, the design of the face mask, the velocity at which the particles hit the face. And in a sense, that's for the other person. And of course, the fit of the mask to the face, therefore preventing particles coming out through the sides and how well they are actually transmitted across the material.

So in this publication, eight types of masks were tested and the scientists measured something called the filter efficiency. And to do this, they assembled commercially available masks that they were able to purchase. And they chose five masks, which had three layers, two were fabric or cotton masks, and one had a one-way valve. And what they did is that they examined the filter efficiency. And this was using particles.

And so they were essentially doing particle counting. Just like that fluorescent dye experiment, in a sense, they were measuring how many particles can actually get through the mask. And the take-home message was that the cloth mask, that is the mask made in a sense by hand, with at best two layers of cotton, had the absolute lowest filter efficiency. That means particles can get in and out of the mask.

Those commercially available masks, which included an activated carbon filter layer, definitely made the cotton mask better. That is it improved its filter efficiency. And you can see on the graph here that you're measuring the particle diameter on the x-axis. And you'll see that there is a blue rectangle. Now, that blue rectangle is within the size range of the SARS-CoV-2 virus.

Because the question is, how well do these masks protect not only the wearer but the general public in the immediate facility from coming into contact with particles of the same size as the virus. And as I just said, the homemade mask had the lowest filter efficiency. Now, how do they actually do these experiments? Well, again, there are standards for mask manufacturers and they need to comply with rules and regulations that are specific to that particular industry.

And there are specific testing machines apparatus. I've put a photograph here on the left-hand side which shows you those machines that measure the filter efficiency and validate whether or not the mask is fit for purpose. And again, in this next series of graphs, they tested the medical face masks. And these had three layers of material in it.

The medical face masks definitely showed an improvement. But guess what? The mask, which is most similar to an N95 mask, the one with the valve had the best filter efficiency. And hence why I immediately tweeted back the other night regarding this particular paper, because it is a very important paper. But again, the topic of the paper is on the filter efficiency of particles within the size range of the virus.

And I'm going to go further into this controversy within this live stream because it does deserve an answer. Now, valves or no valves on masks? Well, the aim of a face mask is to stop aerosols in the size range of 0.006 microns to 10 microns from entering the person's respiratory system. It was concluded in this publication that face masks were highly efficient at the aerosol nanoscale size range.

But not all of them are efficient in this particular size range and only surgical masks of known origin displayed an acceptable efficiency across the aerosol size range. Market available cloth masks were inefficient at any of the aerosol size ranges and the mask with the one-way valve was the most efficient across the examined size range.

Now, I don't think the controversy is finished here because another publication has appeared as well. I've put the DOI up here so you can read the premise results, conclusions, and discussion in this letter to the editor. But the important point to mention is that sick people wearing a mask with a valve could still exhale droplets containing virus particles.

Now, think about that. The data I just presented in the graph showed you that the mask with the valve was most efficient from a filtration viewpoint. But from a virus liberation viewpoint, there is still some potential to expel this into the environment. However, there's controversy, because it's much easier to wear a valve mask for longer periods of time.

And we're going to get into the fact that this is a known valve issue may be a trade-off, because we want to maximize the time people wear a mask. And to do this, we're going to move to some animal research later in this live stream. Now, I want to change topics now, because the whole point of wearing a mask is presumably to limit you from coming into contact with the virus so you just don't get it.

But what about the people who have already been exposed to the virus over the last six months and the hundreds of thousands of cases of SARS-CoV-2 illness that have occurred worldwide? And to do this, I want to review a paper that came out on the 14th of July. The hypothesis of this publication was that non-mask wearing, that is the right of noncompliance with wearing a mask can be used to predict the death rate.

And that together with the age of cohorts of people and their body mass index, it is useful, in a sense, a three-way metric to determine whether or not groups of people are going to likely have morbidity associated with COVID-19. The study reviewed 13 different Western countries and nine Asian countries. And the question was, what is the percentage of people in each country who answered, are you wearing a face mask when you go out into public spaces?

And they looked at the evolution of the death rate from mid-March to late April and into early May 2020. They discovered that with very good accuracy and including six differences in high body mass index, that the strongest predictor of death was noncompliance with wearing face masks. And in fact, statistically, it accounted for 72% of the variation.

The table on the right-hand side is really a figure from this particular publication is pseudo-colored to demonstrate from cold to hot, with hot meaning a very strong correlation or connection between mask-wearing and death rate. And you can see that across countries, across the world, that the noncompliance at the early stages of the pandemic with not wearing a mask out in public predicted, to a very high degree, the death rate.

And really that is fundamental information that I and many other people and policymakers must get across to the general public. That we need to comply with mass squaring and not just in Melbourne during the lockdown at this point in time. Now, what about this opportunity to make emergency face masks? Again, in June 2020, publications have appeared and in mainstream newspapers, there have been wonderful articles demonstrating how you can practically become a maker, start sewing and make your own face masks.

I think that's a great idea. However, we have to understand that a homemade mask does not offer the same level of protection as a commercial mask. The reasons for that are going to become very clear in a few minutes. But what I can say, if you have already made your own homemade mask or planning to do so, or have purchased a cloth mask, remember that suitable materials or fabrics that have high filter efficiency often have very low breathability.

That means it's difficult to breathe through it, meaning that it is going to be hot, uncomfortable, and difficult to wear when you're exerting yourself at all. Meaning you might take it off. You might touch something. Touch a fomite out in the supermarket, for example, or elsewhere, and cross-contaminate yourself. So this study is, again, not so much about viral transmission, but it's about particle filtration.

The conclusions from this study were that repurposing material for homemade face masks comes with its own risks. And in many cases, the fibers can be inhaled and those can cause lung injury as well. So the aim of that paper, as I said, was to demonstrate to home sowers and the maker community what the limitations are of homemade face masks versus standardized commercial PPE masks.

And again, you can look at the graph on the right-hand side of this slide and you can see a decreasing level of filter efficiency. I'm not going to go through all the different materials that were tested. But the one which came closest to mimicking a commercial medical grade mask or a mask manufactured from HEPA material that is a high efficiency, particulate air filter material was able to do.

They're the controls on the top furthermost left-hand side of the graph, and it was denim jeans and in a sense windbreaker fabric, which was the densest and offered the greatest ability to filter the air. But next in line was filtered wool, quilt, cotton, and cotton flannel. And even a sock shows high filtration efficiency, but unfortunately still has a lower breathing resistance. That is the trade off.

So many of you also would have seen the Bill Shorten talking about his own efforts to make a face mask. And again, this is a laudable video. He should be commended for putting this out on social media. However, I want to make the point that making your own face mask does not provide improved or superior filtration or protection from the SARS-CoV-2 virus like a commercially manufactured mask can.

We're going to look at some research from researchers right here in Australia. I'm going to play you another quick video which demonstrates the difference between cloth masks and other masks. I'll play that video now.

And you can see that the medical-grade mask was far more efficient at filtering out droplets being expelled from the nose and mouth. And that's why I believe everyone should be using commercially available masks wherever possible. Now, I want to just review before I go back to this controversy about the issue of whether or not face masks can protect you from illnesses.

Well, let's just put COVID-19 to the side. What about the years and years of research into influenza and other communicable viruses and what people have learned about wearing face masks? And again, on May 12, 2020, a wonderful paper came out that reviewed all of the randomized controlled trials of mask-wearing for influenza transmission and the reduction of influenza transmission.

There is a strong connection between the transmission of SARS-CoV-2 and influenza. And so studying the efficacy of wearing face masks is important research to have documented in the research literature. The conclusion was that wearing face masks, irrespective of infection status is very effective in preventing the spread of influenza within the community.

We must not forget that this issue of co-infections is very important to the immune status of individuals as we move through the months ahead and concurrently now. Because getting influenza is certainly a co-factor which could make the illness of COVID-19 if individuals get that in addition to an influenza flu infection that much worse.

Now, I want to talk about golden Syrian hamsters. I put a picture up here because we owe a great debt of gratitude to these golden Syrian hamsters. I'm going to talk about some medical research which has purposefully infected some of these little hamsters. I want you to be aware of that because the research that I'm about to discuss meant that, unfortunately, these hamsters were sacrificed in this experiment.

However, they validate mask-wearing very clearly, not just for the infected, but for the non-infected as well. This publication came out in the Journal of Clinical Infectious Diseases. It's a very recent publication. I've put the DOI link up here. I recommend you read this and take this information on board. I want to just lay the groundwork for the results.

The scientists established that the golden Syrian hamster was an excellent model for COVID-19 infection. And so what they wanted to do was investigate something called non-contact transmission. Non-contact transmission essentially is the aerosolization into the airspace. We understand that direct contact is sneezing, coughing directly at someone, which they inhale.

But the non-contact transmission is the aerosolization into airspace, and that can land on surfaces and then you can get fomite transmission. And so what they did is that they put these hamsters into different compartments and they tested out various aspects of non-contact transmission versus wearing face masks.

And when they purposefully infected these hamsters, they soon developed clinical signs of infection, which included rapid breathing, weight loss, and pathological changes within their cells. And of course, the symptomology showed acute respiratory distress syndrome, which is the worst hallmark of this virus infection.

And using this animal model, they showed that index hamsters consistently infected what were called naive hamsters. And that is hamsters that were not exposed, which didn't have the virus to begin with. And so the scientists confirmed that virus transmission could occur via either direct or indirect contact.

The reason they do this is that there is controversy in the public domain, public discourse about whether transmission occurs by direct contact with respiratory droplets or the airborne droplet nuclei, which can often dry and become like a dry particle. There is a big issue of coming to terms with the fact that it is not just the wet aerosols, but the dry air assaults and the airborne distribution of these, which can then cross-contaminate other room volumes.

And in this case, these hamsters were housed in different environments to simulate what happens when people are exposed in different room environments. And so I want to take a couple of distills from their publication. And again, all the work was done in a fully contained area and isolation chamber. And there were various cages with these hamsters in there.

And in between the cages, there was not just a fan for distributing the air from virus-contaminated animals that are breathing normally. And then they used surgical masks at different points of the experimental design to achieve a couple of things. So you can imagine putting a surgical mask not just on one side of the cages if you infect a group of hamsters and see whether or not the aerosolization, how many hamsters are going to end up with the virus on the other side.

Similarly, you can have the infected hamsters aerosolizing normally, but you can protect what are called the naive hamsters. That is those hamsters that have not been exposed yet to the virus. And you can see the impact of whether or not masks do or don't work and what are the differences, what are the results, and then what are the conclusions from this?

So, the first experiment, as I said, exposed a group of hamsters to the virus. That is they were purposefully infected. And then there was no mask partition. And so at the end of five and seven days when they sacrifice the animals, they were able to determine that no mask-wearing results in a 66.7% transmission to the non-exposed or naive hamsters.

So that means if you do come into contact with an environment where there is aerosolization of the virus and you're not wearing a mask, well, if you're a hamster, 66.7% of the time, you're going to get the virus as well if you're not wearing a mask. Now, when the mask is placed on the infected hamsters. So the hamsters are on this side and a mask material is put on them.

So they can quite happily aerosolize, but the mask material is preventing or limiting the transmission to the naive hamsters. Guess what? There's only transmission at 16.7%. So a lot of the naive hamsters didn't get COVID-19.


Now, what happens when you put masks on those hamsters? You still infect the same group and same number of hamsters, but you don't put a mask on them, but you do on all the naive hamsters. That is the general public if we all adopt mask-wearing.

And unfortunately, we see that the transmission rate increases to 33.3%.

But remember, if both groups of people wear masks, the percentages are reduced to 16 or so percent. And so we need to put this in context of the changing dialogue which has occurred in the public discourse and news surrounding COVID-19 over the last six months.

We mustn't forget that back in late January, the World Health Organization was not advocating mask squaring. China has been wearing masks pretty much from the start of the pandemic, whereas in Australia and the United States and other countries, mask-wearing has not been compulsory. And if it has been recommended, it is a more recent phenomenon.

I think the research literature which is available now in the peer-reviewed journals, as well as the open-source journals, demonstrates conclusively and that hamster study demonstrates overwhelmingly that mask-wearing is important. It is not a total panacea because remember, people can get sick through the eyes, the conjunctivae or conjunctiva. And that was well known back in the Spanish flu era as well.

But the important take-home message is that now mask-wearing is being advocated. We're getting to the conclusion now. So what's the pathway forward? Well, we're all getting very familiar at repeating this. It's not an exam, but it's something that we're all living on a day-to-day basis. We all understand about social distancing and its importance. The importance of hand hygiene and hand-washing; to deactivate the virus with soap and detergents and alcohol-based sanitizers.

The importance of wearing a mask. Even if you haven't heard anything that I've presented in the last half hour or so in the live stream about the benefits of mask-wearing for symptomatic and pre-symptomatic and asymptomatic people, and in fact, everyone, is that the pathway moving forward must take advantage of what we know from the past, from history and what a lot of these publications are presenting very clearly for us.

Again, there's always emerging literature. This publication also just came out a couple of days ago. They were talking about public health initiatives that are overwhelmingly positive for groups of people. What they're saying is that unless at least 50% of individuals comply with the public health measures, we are not going to see the advantages of the self-imposed quarantine or lockdown.

We must raise awareness wherever possible that the self-imposed measures such as hand-washing and mask-wearing is absolutely crucial and fundamental to controlling the ongoing epidemic. It's not going to stop it completely, but it is going to change the right of disease occurrence in the community. It is fundamental for the government to get out that short term, early initiated, imposed social distancing, combined with things that I can do and my family can do and my friends can do is fundamental to reducing the impact of the SARS-CoV-2 virus in the community and larger world environment globally.

Now, that's what I wanted to talk about today. Each week, we focus on a different aspect of infection control. This week, we've been looking at the pros and cons of face masks, whether or not a valve is isn't good, whether or not a designer mask is your preference. I think that there is a place for all of these masks. I think we just need to wear them all the time, not just in Melbourne, Victoria.

You need to think about what those Syrian hamsters that study did for us. Those results have long-term implications. I know which side of the cage I would prefer to be on. I want to be on the 16 or so percent side. So, therefore, everyone should wear a mask. In any case, my name's Dr. Cameron Jones. Stay safe, and I'll see you next week. Bye, for now.

YouTube Link: 



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Face coverings – Metropolitan Melbourne and Mitchell Shire.


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