Hi I'm Wendy Zukerman and you're listening to Science Vs from Gimlet. On today's show: What does the science tell us about masks? Should we be putting them on or not?
Back in March the message about masks was pretty clear. Healthcare workers need them. But for the rest of us? Don't bother. [1][2]
FAUCI right now in the United States, people should not be walking around with masks… [3]. [60 minutes 3/8]
Here at the CDC they argue that having the average person wear an ordinary mask can be counter productive[4]
The World Health Organization says unless you’re sick, you don't need a mask.[5] [AP March 31]
But just a month later... by April… things started to change[6][7][8]… like, here in New York we were told it's mandatory to wear masks.
Cuomo: All people in public you must wear a mask.[9] [Cuomo press conference 4/15]
The CDC was on the mask train too. But they were like - don't wear medical masks. What you should be wearing is a cloth mask.[10] And suddenly … it felt like Anthony Fauci - was singing a different tune.[11]
FAUCI: Some sort of mask like facial covering I think for the time being should be a very regular part of how we prevent the spread of infection[12]
These days… there’s such a push behind cloth masks that even the surgeon general[13]… is putting out tutorials on how to whip one up at home …
Here’s how you can make your own face covering in a few easy steps with items you can find around the house, like an old scarf, a bandana or a hand towel, or you can make a face covering out of an old t-shirt… It's that easy![14]
But is it that easy? All this flip flopping advice and, confusion, has landed us in a place where some people say, yes, masks are super important for getting this under control … while others are saying, forget about it, we don’t think they do anything … and both sides claim to have science on their side[15].
So what is going on here? Should we be wearing masks or not? A couple of months ago, we published an episode about masks for healthcare workers[16]… but what about the rest of us? When it comes to the pandemic there's a lot of
Cuomo: Put the mask on [Cuomo press conference 4/15]
But then there's Science.
Science Vs The Mask Wars. Coming up after the break.
BREAK
Welcome back. Today on the show - should we be wearing masks - and if we should - what kind?
We're going to start by looking into how good surgical masks are at blocking viruses - these are those blue rectangular masks that you might see your dentist wearing.[17] And we know - the CDC doesn't want the public wearing these masks, they want to save them for healthcare workers.[18] But it looks like a lot of people around are still wearing them.
So to find out if wearing them is a good idea, we called up Ben Cowling[19]… a professor of epidemiology at Hong Kong University. And Ben moved to Hong Kong in 2004, shortly after the SARS epidemic[20] and he's been researching outbreaks ever since.
BC We’ve always been ready to respond when there’s another SARS, and then 2020 here we are with SARS 2
WZ Literally SARS 2
BC Yeah, it’s literally SARS 2, it is!
Ben just published one of the best studies out there looking at how good surgical masks are at stopping viruses.
BC That’s right, we wanted specifically to look at the question of whether if a sick person wore a mask, would it help or not?
Here's what he did. First step. He got this large and weird-looking machine[21].
BC Same size as a human basically, but it’s got this big cone on the end of it
WZ It looks like something that could have come out of Willy Wonka’s factory I reckon.
BC Hahaha
Imagine a tuba connected to all these pipes and filters… So Ben got more than 100 people with viral infections to come into his lab wearing masks and to cozy up to this machine.[22] -
BC and we ask the patient to sit on a stool with their head inside the cone just looking down through the cone to the other end and then sit there for 30 minutes
WZ So when you told the participants in your study you gotta put your head in that cone for 30 minutes, what was the general response?
BC I think they were kind of fascinated by the idea that so many people would have never imagined before
And they're putting their heads in the cone because the machine is going to capture everything that’s coming out of their mouth - what they breathe, what they cough. And Ben repeated the experiment where people were wearing no mask. And this research was done before this new coronavirus[23] - so the people were infected with other stuff… like the flu and some were actually infected with other coronaviruses… that cause the common cold…[24] And Ben looked at what came out when they were wearing the masks and when they weren’t. So, when you zoom in on those 20 or so people who had coronavirus infections….what did he find? Did the masks block those viruses?
BC Yeah! So they blocked virus from common cold coronaviruses in aerosols
So yeah, the masks did help block coronaviruses from getting through. A wrinkle here is that - although we kinda have this idea that sick people are just spraying virus out all the time - in Ben's study that actually wasn't true. Even without the masks, people didn't breathe or cough out much virus[25]. Another wrinkle? Ben wasn't measuring this coronavirus - Sars-Cov-2. So we don’t have enough data to say these masks are a slam dunk here.
But just generally speaking - other studies have also found that surgical masks are pretty good at blocking viruses.[26][27][28] And Ben says that could be because of how these masks are put together. They have these layers[29][30] of different material - designed to make it really hard for the virus to find its way through. So the middle piece is made of a filter material that forces the air to make a zig zaggy path.[31]
BC It’s like putting a drunk person in the start of a maze and asking them to find their way out, you know they’ll just bounce around all the walls and they’ll collapse in a heap before they make it out the other side of the maze. So that’s the kind of concept, not a brilliant analogy but that’s the kind of concept
WZBC The drunk person is the viral particle trying to make its way out into the world
BC Sorry yeah haha
WZ I love it, I love it
BC haha
WZ So bottomline, from your study, and others in this space - cheeky question, but if we had an unlimited supply, should the public be wearing surgical masks?
BC Yeah, if we had an unlimited supply of face masks.. I think everyone should be wearing them all the time… Our study certainly supports the effectiveness of facemasks the fact is we don't have an unlimited supply of facemasks…
Since we don't live in the land of masks and honey ... And there is a short supply. We're being asked to wear cloth masks. Do they work? Unfortunately… when Ben did his study… cloth masks weren't the big controversy they are today… so he didn't look into it.
BC But now looking back, I mean we’re kicking ourselves, because if we had data on a good type of cloth mask, it would be really really useful
WZ From across the ocean, I’m kicking you as well
BC Ah sorry I know
So to find out if cloth masks are worth our time … we need to go elsewhere… to say goodbye to Ben…
Bye bye!
And hello to Anna.
AD Hang on, just let me close the door, I’ve got a Dungeons and Dragon game going on in the kitchen so let’s shut that up
WZ Haha is it your game?
AD No no no it’s my husband’s
WZ Um, my husband too has a Dungeons and Dragon game hahaha
AD Oh really hahaha
WZ What have we done?
AD I don’t know!!
This is Dr Anna Davies… we bonded over our appreciation of nice normal dice with 6 sides - none of this 20 sides business. Anyway. We called up Anna because she's a microbiologist[32] and played a critical role in on one of the few studies we have exploring if cloth masks really can block viruses[33]… She started it back in 2008. It was a few years after the original SARS outbreak in China and she’d seen all these images of people wearing homemade masks in the press.
AD And basically my boss at the time said, well y’know if there were no face masks would a home made mask do anything? So I think it was not an unreasonable study to do
WZ no no, we have now learned it definitely was not an unreasonable study!
AD I know I know and obviously I'm a bit surprised
Anna's study has been getting a ton of attention … and Anna's getting emails from all over about it… so let’s dive into what she did. First, she grabbed some random materials around her house
AD They were slightly random. Household fabrics. I mean I literally put myself in the position of somebody at home, thinking ‘Oh what I’ve got around my house, what could I make a face mask out of… Well it’s just the kind of, here's an old t shirt, here’s an old tea towel from my kitchen
She also got a vacuum cleaner bag, a scarf and a pillow case. It's so bizarre hearing Anna talk about this - because more than ten years ago it was all so abstract. And now it's exactly what people are doing at home. But here's what people can’t do at home. Test these fabrics to see if they actually work and block viruses.
So, unlike the focus of Ben's study - where he looked at what viruses get out when a sick person wears a mask -- Anna would look at whether cloth masks can stop stuff coming in.
And to do this, Anna took all those fabrics into the lab. And then they spritzed a virus[34] into the air, she used a harmless virus that can’t make people sick… and she kind of turned it into a magic missile. So when they launched it at the different fabrics ….
AD You could basically see how well the fabric is filtering this aerosol. It's really cool stuff.
Anna compared how many viral particles got through all the different fabrics. And she spritzed some virus on surgical masks too, so she could see how the fabrics compared to those. So, what did she find? Well, surgical masks were the best in this experiment. They blocked the most virus. Second best? Vacuum cleaner bags. They stopped around 85% of viral particles from coming into the bags.[35]
AD It's high! But you can't make a mask out of it - you can't breathe through it.
Yeah using a vacuum bag as a mask? It's gonna suck. OK, and what about T-shirts, scarves, and pillow cases?
AD The kinds of fabric that are comfortable are not that great.
They blocked roughly half the viral particles coming through. So what does this mean in the real world, where people are using cloth masks to try to stay safe?
WZ If I'm healthy, would wearing a homemade mask help protect me? Based on your research?
AD Uh it probably wouldn’t have any... mm, I don't think our research goes that far. If the results had been ‘Yes, they’re as good as surgical masks,’ then we would have said, ‘Yeah, you can use them instead of surgical masks.’ If the results had been ‘These are awful do not use them, they offer no benefit at all,’ then that would have been clear advice. But the answer was ‘Meh, they're kind of not great but they're not nothing.’
Anna’s hearing from people using her study to say cloth masks can protect them, and she kinda wishes they wouldn't do that…[36]
AD Our study is really. It’s really simple study… like it’s not… and you know, we didn’t test it against the actual virus. Like we didn't test how you know what’s the effect of wear? Cause obviously you’ve got water vapor in your mouth when you breathe out and that’s going to have an effect on the fabric, it will get damp. What's the effect of cleaning on it? I don't know. I mean there's lots of things that we didn't look at.
The few other studies that we have looking at how well cloth masks can block viruses or block particles the size of viruses – they’re kind of all over the place. Some find that cloth masks are basically useless.[37][38]... while others find that they kind of work ok [39][40][41][42] .
So where does this leave us? Well, surgical masks are looking pretty good… and cloth masks -- meh -- but remember this is all about what happens in the lab under controlled circumstances.
We all know the real world is a lot messier than the lab… So what happens when we take our masks out for a spin in the real and messy world… -- how effective are they then?
BREAK
Welcome back. We've found out that in the lab - it looks like surgical masks should do pretty well at blocking viruses... and even cloth masks block out some viral particles too. But what happens out in the real world … when you take these masks for a spin - could they help stop this pandemic?
Well, when you look at places, like Hong Kong, where heaps and heaps of people wear masks[43][44] - and you see that their infection rates are so low - it sure seems like masks are the key here. But the problem is… places like this were doing a tonne of other stuff too[45][46][47] …to keep this pandemic at bay… like really good screening and isolating people who are sick.[48] So we have to look at other studies to see if masks really can help here. For that, we called up this scientist …
OP: Ok hi hi WZ Great! So can you introduce yourself…
So I'm Dr Olga Perski…
Olga[49]… is a researcher at University College London… And to respond to the mask wars… Olga and her team gathered up studies of regular people wearing masks out in the real world. She wanted to find out - did it keep them from getting sick, with stuff like the flu? Olga nixed any studies done in healthcare settings - because she just wanted to focus on regular joe shmoes - you and me[50]… And she ended up with 11 randomized trials. All of these were about surgical masks. Researchers would do stuff like take sick people - and tell some of them or their families to wear surgical masks at home. And then they'd see who got sick. And Olga also found studies outside of the home.
OP we also found a couple of studies conducted in university halls, and where participants were traveling on pilgrimage[51]
One of the studies got people to wear masks on Hajj, a pilgrimage to Mecca[52]. Overall, here’s what they found …
OP There was no good evidence for or against the wearing of face masks in community settings meaning that we can’t actually say whether there is a benefit. We're sitting on the fence essentially
Yeah - there was no difference in the groups told to wear masks and those who didn't.[53][54] Now, Olga’s team has just finished the paper, and it's still going through peer review. But other published reviews have said the same thing . They don't find good evidence that when we regular folk mask up - it stops us from getting sick.[55][56][57]
So why not - given what we've seen in the lab? How can some virus particles be blocked by masks and yet, they don't seem to do anything in the real world? Well, Olga says...
OP 47 We need to consider the different things people do when wearing these masks
And by this she means that even though the mask might block some viruses... it’s possible that the way people wear them - might cancel all that good out[58]. So for example, Olga and others[59] have speculated that people might be touching their masks. Which could be bad - because one study found that this coronavirus can survive on masks for up to 7 days[60]. So say you do get some virus on the outside of your mask, you fiddle with your mask… you get the virus on your fingers… say, your spring allergies are acting up, you rub your eye… and that virus gets in your body.
OP There's the risk that instead of the mask protecting people it might actually act as another way of spreading the virus
Another complicating factor here is that people are bad lab rats. In a lot of these studies, where scientists tell people ‘hey wear this mask’… they don't do it like the nerds want them to[61]! Ben, who you heard from before, with the Willy Wonka cone study, has done a few mask trials[62] - and he says in one of them - only a quarter of the healthy stuck to wearing masks throughout the study[63]
BC and adherence wasn’t great, right? So that’s the kind of the real life difficulties of something like face masks it’s really not that easy
WZ When I look around New York right now, and how they wear them is a total mess, people push it down to talk to someone,
BC yeah?
WZ I saw a woman push down her mask and cough into the air and then put the mask back on
BC Ohhh nooo
Point is -- a lot of us are bad at wearing masks. And while we don't know if the people in these studies got sick because of their crappy mask wearing technique- we did find one study which suggests that if people wear surgical masks properly, it can help. It was a study in a hospital ward where basically everyone - doctors, patients, and visitors -- wore masks, and the infections they looked at dropped by half![64]
So that's surgical masks -- what about cloth masks -- what do we know about how these work in the real world? Well frustratingly...we don’t have studies like the ones we just talked about for cloth masks -- the research hasn't been done.[65][66] Which is a big reason why we have the great mask war going on over cloth masks. Here’s Ben again.
BC So there’s kind of two camps. Two scientific camps. One camp says that ‘most likely they should do some good, so it’s better to have some good than nothing. And despite there being no scientific evidence, there is a mechanistic plausibility, a good reason to believe that they work, so we should recommend them. And that’s the scientific camp that’s now got public support in many parts of the world[67]
This scientific camp[68][69][70][71][72][73][74] is sometimes using lab studies like Anna's to say, it makes sense that cloth masks would block at least - some nasty viruses. Plus when we saw cases rising across America , and we found out that people could spread the virus before they showed any symptoms, some figured, well, cloth masks might be a helpful way to slow this all down.[75][76]
BC But there’s another group of scientists[77][78][79][80] that say you know really without evidence we’re not comfortable in recommending something to be used because it may be doing nothing
And since we don't have good data - there's naysayers.. arguing - well it's possible cloth masks could cause harm, because who knows? Like maybe people feel invincible with their bandana around their face and stop social distancing.[81][82][83] Anna Davies told us, you could kinda argue this either way[84].
AD The problem is there’s so little data out there, that people tend to choose a standpoint based on intuition gut rather than any evidence, and then find the evidence to support it
So that explains some of this mixed stuff in the news. When you look at the scientific picture - we just don't have the evidence we would like to say that cloth masks work - or that they don't. So where do we at Science Vs Stand? Well…given that the good stuff … the good masks… need to go to healthcare workers … perhaps we should see cloth masks as just one tool in the toolbox here. And because we don't know if they're a 20 volt power drill or broken dollar store drill ... we can't count on them to keep us safe. I talked to Anna about this
WZO 37 One way I was trying to think about it… I guess... if I wore it, I'd just need to think it doesn't work, and then if it helps some, if it catches some viral particles that would have gone into my mouth, great, but I really need to be thinking this isn't doing anything so then i keep social distancing and i keep my hands away from face and all that[85]
AD Exactly, you know you should still behave as though you’re not wearing a mask. Because that is the safest thing to do.
And now...time for a little NCVC
JINGLE
Today… we’re diving down, more than 800 meters into the Pacific Ocean, more than 2600 feet. to find Humboldt squid, also known as “RED DEVILS”[86][87]. They are super intense...these squids’ll squirt ink in your face if you get too close[88]...But it turns out they can be a little "chatty"….[89]! Rhey chat by flashing. That is they make their body glow with light-producing organs and then flash patterns with their specialized skin cells.[90]. And recently scientists got a clue about what they might be saying to each other. Researchers in California sent cameras down into the sea[91]... and recorded the flashing. And they noticed that the squids seem to flash their lights the most when they're chasing down food while hanging out in groups.[92] . So scientists think that some of this flashing might be squids saying “hey look out! That’s MY fish”...and avoid fish-food-fights.[93]? But who knows? Perhaps they're saying I'm HUNGRY… Or maybe… this is all just lunchroom gossip … and they’re talking crap about Jake… yknow Jake, that annoying Squid… omg you totally know about Jake…. he's the one that… can't mute his zoom… or maybe he can and he just doesn't want to….
That's Science Vs.
To see a video[94] of the squids talking to each other, head to our show notes.
CREDITS- CITATION
This episode was produced by me Wendy Zukerman with help from Michelle Dang, Rose Rimler, Meryl Horn, Laura Morris and Sinduja Srinivasan. We’re edited by Blythe Terrell with help from Caitlin Kenney. Fact checking by Diane Kelly. Mix and sound design by Peter Leonard. Music written by Peter Leonard, Marcus Bagala, Emma Munger, and Bobby Lord. A huge thanks to all the researchers we got in touch with for this episode, including Dr. David Simons and Benjamin Burford. And special thanks to the Zukerman family and Joseph Lavelle Wilson.
I'm Wendy Zukerman, fact you next time.
[1] JAMA guidelines March 4, 2020: Not for healthy people who aren’t taking care of someone with respiratory illness “there is no evidence to suggest that face masks worn by healthy individuals are effective in preventing people from becoming ill.” Info taken from WHO
[2] March 20, 2020: Brief overview with WHO and countries’ policies at the time
[3] March 8: right now people should not be wearing masks: https://www.youtube.com/watch?v=PRa6t_e7dgI
[4] Good Morning America March 30: https://www.youtube.com/watch?v=rnP7v0SsVq8 [40 seconds]
[5] From WHO- in April: a medical mask is not required, as no evidence is available on its usefulness to protect non-sick persons. However, masks might be worn in some countries according to local cultural habits…
[6] san francisco (last updated april 24): You are required to wear something to cover your face when shopping, taking transit, or getting healthcare.
[7] washington, DC, april 15: The new order clarifies that face masks are required for: hotel workers, guests, and visitors; individuals using taxis, ride shares, private transportation providers; workers and customers of food sellers; and strongly encouraged for workers and individuals using public transit
[8] Michigan, April 24: Governor Whitmer Extends Stay Home, Stay Safe Order, Directs Michiganders to Wear Homemade Masks in Enclosed Public Spaces: require people to wear homemade, non-medical grade face coverings when they enter enclosed public spaces...also require employers to provide at least cloth face coverings to their employees.
[9] April 15: https://www.governor.ny.gov/news/video-audio-photos-rush-transcript-amid-ongoing-covid-19-pandemic-governor-cuomo-issues-1
[10] April 10: CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies), especially in areas of significant community-based transmission.; https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html
[11] FAUCI When you are in a group of people that you can't avoid the 6 foot limit.. you might want to wear a cloth face protection better known as a mask. [WSJ The Journal 4/7] https://www.wsj.com/podcasts/the-journal/dr-anthony-fauci-on-how-life-returns-to-normal/d5754969-7027-431e-89fa-e12788ed9879
[12] Dr. Fauci, testifying before the Senate on May 12, 2020. Video from the PBS Newshour website [3:07:11]
[13] https://twitter.com/Surgeon_General/status/1233725785283932160: Seriously people- STOP BUYING MASKS!
They are NOT effective in preventing general public from catching #Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk!
[15] See our cites 67-78, 76-79
[16] March 23, 2020: https://docs.google.com/document/d/e/2PACX-1vTkKukaeeWnF4C7wOQNtqOk7B7eOAZ_bS0CgMniRpaDfRy6Rg-wz7hiAuLfwhxz7mZubMt2_pdodPio/pub
[17] FDA: Surgical masks are fluid-resistant, disposable, and loose-fitting devices that create a physical barrier between the mouth and nose of the wearer and the immediate environment. They are for use in surgical settings and do not provide full protection from inhalation of airborne pathogens, such as viruses.
[18] The cloth face coverings recommended are not surgical masks or N-95 respirators. Those are critical supplies that must continue to be reserved for healthcare workers and other medical first responders, as recommended by current CDC guidance.
[19] https://sph.hku.hk/en/about-us/faculty-and-staff/academic-staff/cowling,-benjamin-john
[20] https://www.cdc.gov/sars/about/fs-sars.html
[21] FIG. 1. Diagram of G-II exhaled breath bioaerosol collection system (U... check out pic here: https://twitter.com/bencowling88/status/1246004236590010369
[22] Infections by at least one respiratory virus were confirmed by reverse transcription PCR (RT–PCR) in 123 of 246 (50%) participants. Of these 123 participants, 111 (90%) were infected by human (seasonal) coronavirus (n = 17), influenza virus (n = 43) or rhinovirus (n = 54)
[23] Participants were recruited year-round from March 2013 through May 2016
[24] Coronavirus-infected participants coughed the most with an average of 17 (s.d. = 30) coughs during the 30-min exhaled breath collection. Also - table of symptoms.
[26] Surgical masks provided about twice as much protection as home made masks…
[27] Surgical mask was highest- filtered 89.52% of bacteriophage. Cotton T-shirt only 51%, Cotton Mix 70%, Linen 62%...
[28] Study by Cowling and others using a similar setup found that surgical masks reduced the amount of influenza RNA researchers could detect from both small and larger respiratory droplets. The effect was much stronger for larger droplets, but the study indicates the masks can reduce aerosols to a limited degree.
[29] Surgical masks are three-layers, which are specifically made so the outside is waterproof, the middle layer is a filter, and the inner layer is cotton to absorb moisture.
[30] https://www.nap.edu/read/11637/chapter/4#34 Typically, a fluid-resistant disposable medical mask has multiple layers or plies of different nonwoven fabric materials that form a composite material laminate that is used for the nose and mouth section of the mask (Maturaporn, 1995). For example, a three-layered laminate structure is pleated and sized to cover the wearer’s nose and mouth.
[31] https://www.nap.edu/read/11637/chapter/4#23 The material creates a tortuous path, and various mechanisms result in the adhesion of particles to the fibers without necessarily blocking the open spaces, still allowing air to flow easily across the filter (Revoir and Bien, 1997).
[32] https://www.researchgate.net/profile/Anna_Davies5/experience
[33] https://www.cambridge.org/core/journals/disaster-medicine-and-public-health-preparedness/article/testing-the-efficacy-of-homemade-masks-would-they-protect-in-an-influenza-pandemic/0921A05A69A9419C862FA2F35F819D55
[34]Bacteriophage MS2 (MCIMB10108) is a nonenveloped single-stranded RNA coliphage, 23 nm in diameter, known to survive the stresses of aerosolization … As we have tested a viral pathogen smaller than influenza and a bacterial pathogen larger than influenza, we have tested the face masks with a suitable challenge across the size range of influenza virus particles.
[35]See Table 1 https://www.cambridge.org/core/journals/disaster-medicine-and-public-health-preparedness/article/testing-the-efficacy-of-homemade-masks-would-they-protect-in-an-influenza-pandemic/0921A05A69A9419C862FA2F35F819D55
[36] E.g. https://www.kgw.com/article/news/health/coronavirus/coronavirus-how-to-make-mask-best/283-b737258a-c93b-4dd0-be7b-c6ec8a75447b
[37] https://bmjopen.bmj.com/content/5/4/e006577#T1 Laboratory tests showed the penetration of particles through the cloth masks to be very high (97%) compared with medical masks (44%) (used in trial) and 3M 9320 N95 (<0.01%), 3M Vflex 9105 N95 (0.1%)..; cloth masks used were two layer, made of cotton
[38] https://www.acpjournals.org/doi/10.7326/M20-1342
[41] Found a lot of the particles got through "Average penetration levels for the three different cloth masks were between 74 and 90%, while N95 filter media controls showed 0.12% at 5.5 cm s−1 face velocity "
[42] NAP-- 2006 Regarding cloth masks-- says the tighter the weave the better, but the tighter the weave the harder it is to breathe and means people will be unlikely to comply. Hesitates to recommend for or against cloth masks because of lack of research.
[43] Hong Kong mask study A total of 10,050 persons were observed. Only 337 (3.4%) persons did not wear face mask. The daily compliance of face mask usage was 97.2%, 97.1%, and 95.7% over three consecutive days in all 18 administrative districts in HKSAR.
[44] In three surveys - 1000 people each - “we estimated that 74.5% [end of january] and 97.5% [beginning of feb] and 98.8% [mid-March] of the general adult population wore masks when going out.” Unclear if that NPI helped flatten the curve, 61.3%, 90.2%, 85.1% avoided going to crowded places, and 71.1%, 92.5%, and 93.0% reported washing or sanitizing their hands more frequently, respectively (Table 2).
[45] PREPRINT: This paper identifies several countries (Hong Kong, Thailand, Taiwan, Japan) with low covid-19 mortality rates (less than 1 per million) and suggests that mask wearing might have contributed to this. However, the authors do not account for other policies, such as contact tracing or screening travelers entering the country.
[46] Thailand: Cases: as of may 14, total of 3018 cases (<0.05% population affected, population data from the world bank).
Mask policies: in march, the thai government ordered the public to wear cloth masks (43 million has been distributed, and had mask use recommendations since january 29)
Other policies: conducting thorough screening of travelers (at airports more than 4.4 million screened). the may 12 situation report: the thai government is continuing "screening, isolation, quarantine or quarantine for observation to control and prevent the disease are implemented among passengers departing from areas or countries affected by COVID-19". mask wearing among the public is a part of the recommendations, but combined with social distancing.
[47] Taiwan: “big data approach”. Cases: As of may 14, they’ve had 440 cases. Mask policies: increased mask production in jan/feb and instituted a mask policy on feb 6. Other policies: (All actions listed here)
Border Control, Case Identification, and Containment: January 27: integrated patients’ past 14-day travel history with national health card -- accomplished in 1 day -- allowed the government to track individuals at high risk, who were immediately quarantined and electronically monitored; Resource Allocation: Logistics and Operations: set a mask price (and increased mask production); Communications: daily press briefings by the minister of health and welfare, public health announcements
[48] The general community in Hong Kong have also changed their individual behaviours in response to the threat of COVID-19. People have been choosing to stay at home more, and in our most recent survey more than 90% of respondents reported to avoid going to crowded place But they did other stuff too… "The containment measures used to control COVID-19 in Hong Kong include intense surveillance for infections not only in incoming travellers but also in the local community, with around 400 outpatients and 600 inpatients tested each day in early March (personal communication, GM Leung). Once cases are identified they are isolated until they recover and cease virus shedding."
[50] PREPRINT: https://www.qeios.com/read/1SC5L4
[51] Of the 11 RCTs collected - participants on Hajj pilgrimage (26). Two studies were conducted in university halls of residence (37,38).
[53] Available evidence from RCTs is equivocal as to whether or not wearing face masks in community settings results in a reduction in clinically- or laboratory-confirmed viral respiratory infections.
[54] Another limitation of the available facemask studies is the mixing of interventions. In four trials in the community setting facemasks were combined with hand hygiene as an intervention, which makes it difficult to ascertain the efficacy of masks alone
[55] https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article In this review, we did not find evidence to support a protective effect of personal protective measures or environmental measures in reducing influenza transmission. Although these measures have mechanistic support based on our knowledge of how influenza is transmitted from person to person, randomized trials of hand hygiene and face masks have not demonstrated protection against laboratory-confirmed influenza, with 1 exception (18)..... In pooled analysis, we found no significant reduction in influenza transmission with the use of face masks (RR 0.78, 95% CI 0.51–1.20; I2 = 30%, p = 0.25) (Figure 2).
[56] 2009 study "We concluded that household use of masks is associated with low adherence and is ineffective in controlling seasonal ILI. "
[57] Some more recent rapid reviews (pre-prints not published):
PREPRINT Review 4/7: Cochrane authors did an updated look: “Most included trials had poor design, reporting and sparse events. There was insufficient evidence to provide a recommendation on the use of facial barriers without other measures … we recommend the use of masks combined with other measures.”
PREPRINT Review 4/6: “The evidence is not sufficiently strong to support widespread use of facemasks as a protective measure against COVID-19. However, there is enough evidence to support the use of facemasks for short periods of time by particularly vulnerable individuals when in transient higher risk situations.”
[58] Notably, improper use of face masks, such as not changing disposable masks, could jeopardise the protective effect and even increase the risk of infection.
[60] Study found the virus can survive on face masks for 7 days
[61] McIntyre et al studied the effectiveness of the use of a surgical mask placed on a subject with a viral respiratory infection living in a household of two or more people. The key findings are that <50% of participants were adherent with mask use and that the intention-to-treat analysis showed no difference between arms. Adherence to mask wearing decreased to 31% over the course of the study. We concluded that household use of face masks is associated with low adherence and is ineffective for controlling seasonal respiratory disease. However, during a severe pandemic when use of face masks might be greater, pandemic transmission in households could be reduced.
[62] Study by Ben Cowling that examined the use of surgical masks and handwashing for the prevention of influenza transmission in Hong Kong also found no significant difference between the intervention arms. 45% (21%) of sick subjects (household contacts) in the face mask arm reported wearing a mask often or always during the follow-up period, compared to 30% (1%) and 28% (4%) in the control and hand hygiene arms, respectively. More than one in four household contacts in the face mask group did not wear a surgical mask at all during the follow-up period.
[63] The above cite is the pilot study leading to this next study by Ben, which saw 49% sick, 26% contacts adhered to wearing surgical masks in facemask plus hand hygiene group vs. 15% and 7%, respectively, in control group.
[64] Mask compliance was very high, >98%) and infections dropped by half. [10.3% (95/920 patients) in the premask period to 4.4% (40/911) in the mask period.] https://academic.oup.com/cid/article/63/8/999/2389110
[65] https://www.bmj.com/content/369/bmj.m1435.short . To our knowledge, there are no trials of cloth masks in the general public.
[66] Cloth masks are commonly used in developing countries and many non-standard practices around cleaning and reuse have evolved. However, no RCTs of cloth masks have been published.
[67] Examples of some federal recommendations that changed mid-way through the outbreak:
US CDC Germany - Federal Agency RKI
France - mandatory in high schools and on public transportation
[68] https://onlinelibrary.wiley.com/doi/pdf/10.1111/resp.13834 Various materials have been assessed for homemade masks with differing outcomes…” Weighing up all these considerations, there is modest evidence to support widespread community use of uni- versal masking, which includes cloth masks to help reduce transmission of SARS-CoV-2.”
[69] PREPRINT: Public masking theoretically works to drive down transmission at the population level.
When a large portion of the population is wearing masks, both asymptomatic spreaders of the pathogen as well as the healthy will be masked. The key to public masking as transmission control is in source reduction.;
The evidence from historical studies, filtration studies, and observational studies combined with the simple logic of masking asymptomatic transmitters of SARS-CoV-2 together suggests that mass public masking may be an important public health intervention.
[70] However, homemade cloth masks have also been shown to reduce droplet excretion caused by speech, and although not as effectively as surgical masks, masks made from cotton T-shirts significantly decreased the number of respiratory microorganisms expelled by coughing (Davies study).
[71] In conclusion, in the face of a pandemic the search for perfect evidence may be the enemy of good policy. As with parachutes for jumping out of aeroplanes, it is time to act without waiting for randomised controlled trial evidence.
[72] Atlantic article (written by researchers)
[73] Commentary “Mass masking for source control is in our view a useful and low-cost adjunct to social distancing and hand hygiene during the COVID-19 pandemic.“
[74] Fauci, April 3, 2020:https://www.youtube.com/watch?v=CXjRfBa0pYE&feature=youtu.be&t=241
[75] https://www.nature.com/articles/s41591-020-0869-5
[76] See Recent Studies at bottom of page
[77] WHO Guidance (April 6, 2020): the wide use of masks by healthy people in the community setting is not supported by current evidence and carries uncertainties and critical risks.
[78] Dr. Daniel Dikema, past president of the Society for Healthcare Epidemiology of America quoted: “Maybe it could be helpful, but I just don’t think the evidence is there for it...If you’re going to wear a home-made mask, it should not replace physical distancing, good hand hygiene and the instructions about not touching your face, eyes, nose and mouth”.
[80] While people have turned to masks as protection against COVID-19, masks often provide nothing more than a false sense of security to the wearer https://theconversation.com/what-really-works-to-keep-coronavirus-away-4-questions-answered-by-a-public-health-professional-132959
[81] WHO guidance (January 29 2020): Wearing medical masks when not indicated may cause unnecessary cost, procurement burden and create a false sense of security that can lead to neglecting other essential measures such as hand hygiene practices
[82] (1) Wearing a face mask may give a false sense of security …. the quality and the volume of speech between two people wearing masks is considerably compromised and they may unconsciously come closer. While one may be trained to counteract side effect n.1, this side effect may be more difficult to tackle….It is necessary to quantify the complex interactions that may well be operating between positive and negative effects of wearing surgical masks at population level. It is not time to act without evidence.
[83] Their use may result in those wearing the masks to relax other distancing efforts because they have a sense of protection
[84] Perfect example of different academics saying different stuff: https://www.sciencemediacentre.org/expert-comments-about-face-coverings-and-covid-19/?utm_source=AusSMC+mailing+list&utm_campaign=69356a219f-EMAIL_CAMPAIGN_2020_05_01_12_40&utm_medium=email&utm_term=0_90d9431cd5-69356a219f-126964357
[85] PREPRINT Review 4/10: recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies
[87] Dosidicus gigas (d’Orbigny, 1835) (jumbo flying squid or Humboldt squid), sometimes known as the Red Devil squid be- cause it weighs up to 40 kg and occasionally investigates SCUBA divers to see if they might be edible.
[89] visual behaviors have not been associated with similar ecological contexts in a deep-living animal. In its deep daytime habitat, we found that D. gigas more frequently utilized the variable chromatic displays flashing (rapid alteration between pale [P] and dark [D]; P = 0.24) and flickering (dynamic mosaic of scattered pigmentation; P = 0.019) when in the presence of many conspecifics (ANOVA with Tukey’s honest significant difference [HSD]; SI Appendix, Fig. S2B and Table S2), which is congruent with prior observations of their use during group spawning activities in shallower waters. Using principal component analysis (PCA), we found that variance in chromatic behavioral components by D. gigas at depth was aligned with foraging status and conspecific abundance
[90] As opposed to the common tactic of altering the intensity of light produced by individual photophores, D. gigas may use pigmentation patterning to selectively reveal and conceal different regions of an entirely luminescent body. While in most cases, photophores are external and designed to project light outward, those of D. gigas are instead internal and radiate light within the muscle tissue of the fins, mantle, head, and arms...we postulate that D. gigas displays pigmentation patterns against a glowing backdrop created
by bioluminescence, which would likely enhance pattern visibility under low-light conditions.
[91] To investigate the role of visual signals in foraging and group behaviors in deep-living cephalopods, we used high-definition (HD) video cameras mounted on electrohydraulic and electric remotely operated vehicles (ROVs) to study the behavior of the Humboldt squid (Dosidicus gigas) in its natural daytime habitat in the California Current at depths between 266 and 848 m
[92] Squid pursuing prey were predominantly darkened (D, sandy [S], or countershaded [CS]) and then shifted to disruptive pigmentation (BPD) immediately before striking at prey. During the strike, D. gigas typically went D, followed by an abrupt transition to P. These whole-body components are similar to “signifiers” (11), or signals that indicate strong and precise messages—perhaps in this case, an intent and attempt to capture prey.
[93] These components and their usage may resemble “positionals” (11), or auxiliary components that provide additional information. As such, they may not be directly related to the foraging sequence, but could serve as signals of social dominance (32), signaler quality (36), or deimatic behaviors (6) directed at nearby conspecifics.
[94] https://youtu.be/iANgyT95bmA