I recently co-authored a scientific commentary on this, ask me anything!

"Promoting simple do-it-yourself masks: an urgent intervention for COVID-19 mitigation" (Svara et al. 2020)

Pre-print available at https://link.medium.com/LY7RRNr2X4

Summary: "We demonstrate that widespread use of masks by the general population could be an effective strategy for slowing down the spread of COVID-19. Since surgical masks might not become available in sufficient numbers quickly enough for general use and sufficient compliance with wearing surgical masks might not be possible everywhere, we argue that simple do-it-yourself designs or commercially available cloth masks could reduce the spread of infection at minimal costs to society."

The biggest challenge is to overcome the mental block of decades of onetime use masks that have to be disposed in incinerators and be produced by ISO 9001 certified medical factories.

During world war 2 it was normal to use reusable cotton masks. They just need to be put into boiling water for a few minutes to kill sars-cov-2 at 100%.

You should try to get into touch with C. Drosten from Charité hospital Berlin. He recently stated in an interview that self-made masks could have a certain value, so he is not totally averse to this concept and Spahn [1] will listen to him.

China has been promoting it, now czech republic is doing it. If Germany also starts promoting it, that will help immensely.

The same goes for the hand sanitizer, any +70% alcohol/ethanol will do. No need to be from a factory with medical certifications.

I am in France, there is a total lock down here but police still wears no masks and so does nobody else. Super markets have no hand sanitizer at the entrance so the virus will continue to spread.

Masks cost nothing compared to the economic damage of the shut down.

[1] German minister of health

Edit: For those downvoting me, I'd sincerely be interested to hear your arguments.

If the intended goal of wearing a mask is to protect others (since you have no way of knowing that you're not infected), then there's no practical reason that a mask can't be reused, whether sanitized or not.

> They just need to be put into boiling water for a few minutes to kill sars-cov-2 at 100%.

I was looking for information on (high) heat killing viruses such as sars-cov-2. Are you able to point to a reliable source on this?

Heat at 56°C kills the SARS coronavirus at around 10000 units per 15 min (quick reduction).

Hence I'd assume that boiling will be reasonably effective.

Source: WHO https://www.who.int/csr/sars/survival_2003_05_04/en/

Are you aware of any viruses not killed by high heat?

According to an article on Quora, "At What Temperature Do Viruses Die?" ¹, for what it's worth:

> All [known] strains of virus can be inactivated at 70 °C.

For reference, an autoclave used for sterilization is around 121 °C.

> A minimum temperature range to inactivate most virus is 48°C to 60°C. Some virus still able to survive at temperature below 60°C e.g. adenoviruses(dsDNA naked virus) relatively thermostable, it able to withstand temperature at 56°C for 10min.

¹ https://www.quora.com/At-what-temperature-do-viruses-die-1

Viruses exist where there is life, it's not a mound I'm willing to die on, but it's accurate here on Earth. There is life that lives in temperatures higher than 70 °C, therefore there are viruses that can survive in temperatures higher than 70 °C: http://www.rcn.montana.edu/Publications/Pdf/2005/4_18Young.p...

Thank you, I stand corrected! Please everyone disregard my previous comment and find a more reliable source of facts.

There can be some or many kinds of viruses that survive under all sorts of conditions, by that doesn't necessarily imply that a particular virus does so as well.

The question was of any virus not a particular virus.

I imagine viruses from underwater volcanic plumes would be pretty heat tolerant. But I don't know if they are a danger to humans or if we are too cold to host them.

How hot is high heat? There are viruses that infect archaea that live in extreme conditions including near-boiling water.

> I was looking for information on (high) killing viruses

They're not really alive, so they can't be killed. But you can destroy vital parts of them and make them unable to reproduce.

https://en.wikipedia.org/wiki/Denaturation_%28biochemistry%2...

Respectfully, I wish people would stop popping into discussions about coronavirus to say "Actually, ...".

Most educated people know that viruses aren't alive in the traditional sense. People who aren't as educated simply don't care, and I don't blame them. Using the more scientifically precise term helps nobody, except scientists, in this situation.

Should software engineers stop using the word "kill" in POSIX-land because CPU processes aren't really "alive"? Give me a break.

I didn't bat an eye at this until you dropped in with a "Respectfully..." that sounded awfully insincere. Did your sentence really intend to convey respect? Because it came off as disingenuous.

You're searching for malice where there is none. I said nothing disrespectful.

> Respectfully, I wish people would stop popping into discussions about coronavirus to say "Actually, ...".

I answered his question while also correcting a minor mistake. Also I'm not sure what you're quoting there.

> Most educated people know that viruses aren't alive in the traditional sense. People who aren't as educated simply don't care, and I don't blame them.

Are you trying to insult your grandparent? Most people on HN aren't willfully ignorant and are quite open to new knowledge.

It’s controversial. Some would characterize viruses as alive (because they replicate and evolve). So it’s fair to say that you can kill them (prevent from replicating). Debating the semantics of this is not helpful.

And in the non-controversial case - i.e. prions, people generally don't use the term "kill", they use the term "deactivate".

Debating the classification of life, while otherwise interesting, should not derail a conversation about practical steps to fight an ongoing pandemic.

Here's a mask pattern and some additional information from Forbes. It also links to the CDC's comment.

https://www.forbes.com/sites/tjmccue/2020/03/20/calling-all-...

> In settings where facemasks are not available, HCP might use homemade masks (e.g., bandana, scarf) for care of patients with COVID-19 as a last resort. However, homemade masks are not considered PPE, since their capability to protect HCP is unknown. Caution should be exercised when considering this option.

https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/f...

This is because the medical industry needs proven methods, and they still suggest homemade masks as a last resort. Maybe we should all be wearing homemade masks in public.

I've been promoting this idea as well. https://www.facebook.com/edelsmurf/posts/10157054028823201

I've sent pleas to several local and national government agencies and health directors, but it's unlikely that such e-mails will be read, so information needs to be disseminated another way. The fact that the western world hasn't called for widespread use of even cloth masks is unconscionable. Presume you're already infected to protect others.

For reference, the government of Czech Republic made masks (of any type, including self made or even scarfes) mandatory while out of home. This has been in force for a few days & is actively enforced wit a couple people already getting hefty fines.

IMHO this is a really good idea, especially because people who are infected and dont know that yet are less likley to infect others. How good the mas is at protecting you is pretty much secondary concern at this point in time.

> the government of Czech Republic made masks (of any type, including self made or even scarfes) mandatory while out of home.

That is an amazingly forward-thinking position that we should applaud. The mask thing will be one of those “obvious” things that we’ll look back on in a couple of years and shake our heads at.

Unfortunatelly, this (mandatory masks) seems like one of the Czech Republic rules that has not yet been widely copied elsewhere.

BTW, its quite an interesting cognitive change - basically in a span of about two days everyone in public has a mask, even anchors and politicians in news coverage! Even the sign language interpetters!

Also I found out I feel rather uneasy now watching footage from affected areas, some of them in worse situation than us, with people not wearing any masks.

Such a simple way to protect otjers once you thing about it a bit, yet not universally adopted so far...

The Czech government was advised by Taiwan, I recall. Could this be the basis?

The Taiwanese response has been exemplary.

The argument is usually that it has limited effect when it comes to protecting the wearer. Simpler masks or home made masks can probably prevent transmission somewhat from the wearer by reducing the reach of droplets.

The argument against masks is based on 1) that people want them to protect themselves 2) that there aren’t nearly enough masks to do so.

So as I understand it, the authorities that say “don’t wear a mask” isn’t answering the question “would transmission be reduced if everyone wore a mask?”, but rather the question “Should I get a mask to protect myself”. Those are two very different questions.

I haven't seen any evidence supporting the argument that they do not protect the wearer. The argument seems to be that they aren't 100% effective at that, and therefore shouldn't be used for those purposes, which doesn't make any sense. Even 20% reduction in the amount of incoming droplets is significant - both for protecting the wearer, and for reducing R0.

Part of the reasoning is that people who believe masks provide them full protection will take more risks than otherwise. Combine that with hoarding and other behaviors and it's possible that promoting widespread use of masks would cause new problems the west doesn't already have.

If we had successfully promoted "wear a mask when you're sick" as general US policy in advance we probably wouldn't have these supply chain issues and it would be safe to advise people just wear a mask at all times during the crisis. We didn't, so most people don't have any masks, which means they're going to look at this crisis + advisory and panic buy a big pile of them when supplies are already limited.

I agree that public health authorities have not lied, but that's not the point. "Would transmission be reduced if everyone wore a mask?" is exactly the kind of question public health authorities should be asking! The answer seems to be "yes" even for homemade masks. So, public health authorities should be promoting massive production, testing, and use of masks.

I use a home-made mask. It's made from two layers of fabric from a "fitness t-shirt" with a layer of filter paper from an air filter in between. I wash it in the washing machine and replace the filter between each use.

It completely covers my nose and mouth and chin and wraps around over my ears. I tie it in the back with 4 ties one on the top edge and one on the bottom edge.

I have friends tell me "that's dangerous! It may trap particles behind it and make you sicker!"

I'm willing to take my chances. I believe

- combined with my eyeglasses, it will keep me from touching my face and eyes when I'm out

- if someone a few feet away coughs, the large droplet that the virus is riding on will surely get trapped. The pores don't need to be virus-sized to do that.

I have a proper "Gas Mask" but I want to save that for a gas attack. That's why we all have one.

The NY Times ran an op-ed about this:

https://www.nytimes.com/2020/03/17/opinion/coronavirus-face-...

I've also seen people mis-wearing N-95 masks. I was behind a couple in the supermarket yesterday who were wearing them and every few minutes they were reaching up to readjust their noseclips. I got this on video, it was so perversely amusing to me. I hope they don't get sick.

I think if you're going to make a post like this, it's reasonable to expect that you present some actual evidence, or is your whole argument that we should ignore evidence?

"Homemade masks appear to be reasonably effective" is hardly a compelling case.

I don't think the parent's point was that we ignore evidence but that in the absence of evidence (as opposed to evidence suggesting the contrary), we should use priors to guide what we do. In this case, while there are no double blind randomised studies that suggest that widespread mask use reduces R0, priors tell us that masks use protect against infection in other settings.

If we were to weigh the priors, the existing evidence would be leaving towards mask use having a protective effect. The question that we should ask ourselves is, what if the reality turns out to be different? There are 2 scenarios. First, mask use is harmful and the second, mask use has no effect on transmission. The first is very unlikely given what we know and the second will mean that if mask use is encouraged, it will be wasted resources for no gain. If these resources that were wasted were easily obtainable i.e. masks made of old clothing etc, then the downsides aren't serious at all but could have very good upsides if the priors were right.

So I agree, that we should encourage widespread home-made masks use and leave the disposable ones to the healthcare workers.

How can you rule out the possibility that mask use has a net negative effect so easily?

Wearing masks is common in several asian countries even before c19 was a thing and I'm not aware of anyone showing that it's causing harm at the population level. I consider that reasonable evidence that wearing them has no significant negative physiological effects. I could see negative behavioral effects such as making people more careless because they're feeling safer. But again, effective containment in above-mentioned countries would also serve as evidence against that actually being an issue.

The hypothesis that face masks have a net negative effect is a very strong claim, before considering it we'd need some evidence that points in that direction.

I guess if you believe that's actually true, you should be advocating for doctors to stop wearing masks...

But that's not something we do, because we have enough priors that masks help that we will continue to use them.

Simple reasoning. We know that viruses can be transmitted through saliva. Covid-19 generally presents with a cough. Coughs aerosolize saliva. Wearing a mask or face covering catches most particles, and absorbs energy from all particles, so they dont travel as far. Less virus mass, and a smaller projection plume will result in less spread. Less spread results in a lower R0.

I realize that you are just enjoying being contrary here, but please try to think through your argument and ensure it isn't incorrect in itself before posting.

Ah! prefer inaction to potentially imperfect action argument, I see.

Also, how does "what we know" make this unlikely?

Another study on homemade masks: https://www.researchgate.net/publication/258525804_Testing_t... "Both masks significantly reduced the number of microorganisms expelled by volunteers, although the surgical mask was 3 times more effective in blocking transmission than the homemade mask. Our findings suggest that a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection."

This is by no means a personal attack but this is approximately the thought pattern the parent comment is arguing against.

Absence of evidence does not prevent you from making decisions or otherwise coming to conclusions. The fact is, you can make decisions with no evidence at all. Your outcome may be no better than chance but also likely no worse.

Not making a decision can be worse than chance, especially in time critical or low information environments and if you always “wait for the evidence” you will end up being worse than a magic 8-ball at the most crucial moments.

There is no "not making a decision". It's not that you can make decisions without evidence, you must make a decision even without evidence. Not wearing a mask is as much as a decision as wearing one.

Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population. Marianne van der Sande. 2008. doi:10.1371/journal.pone.0002618

Here's a source that supports OP's claims: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3373043

I run freesewing.org, the website linked to in the Forbes article (1). The university hospital here in Antwerp where I live is actively reaching out to the community asking them to make masks. (2) I'm not a scientist, but here's something that I can do, so I'm trying to help. I trust the doctors, that's good enough for me.

(1) https://www.forbes.com/sites/tjmccue/2020/03/20/calling-all-... (2) https://www.uza.be/mondmaskers. (in Dutch)

That is a misleading statement. The CDC has in fact changed its recommendations to recommend in a crises, even HCPs use home-made masks [0]

Health care providers, scientists and health officials are rapidly changing and adapting to the situation. It probably is a good idea for all people to wear homemade / improvised masks to reduce R0

But I'd still hope that civilians with large stores of N95 masks or other PPE would consider donating them to healthcare workers. The optimal scenario seems to be that non-HCPs stay home as much as possible, wash hands, sanitize and wear improvised masks when leaving home, and donate PPE to healthcare workers

9% of COVID-19 cases in italy are HCPs

[0] https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/f...

> But I'd still hope that civilians with large stores of N95 masks or other PPE would consider donating them to healthcare workers.

I was at Home Depot today and was surprised to see N95 masks available, though limited in number per customer.

How widespread is widespread? Japan, South Korea, China, Hong Kong, Taiwan… these are countries in which people wear masks in large numbers on a normal day.

They all still have an R0 above 1.

They also happen to be the countries that have the most control over the epidemic.

https://studylib.net/coronavirus-growth

Those countries also have higher population densities and public transport usage than some of the western countries. How can you say the mask isn’t helping?

> How can you say the mask isn’t helping?

I didn't but I also didn't make the claim that they would help so I suggest we start by getting claimants to back up their claims before we get anyone checking claims to prove negatives.

We need universal mask wearing AND unlimited testing. South Korea showed it works. In Japan, even without widespread testing the spreading is still slower than the west. It's true Singapore does not mandate mask use, but they have thorough contact tracing and draconian quarantine laws.

Excuse me - what "draconian quarantine laws"?

You could lose your residency right for violating quarantine.

https://www.channelnewsasia.com/news/singapore/covid19-coron...

https://www.wsj.com/articles/asian-countries-wield-fines-jai...

How is that draconian? If you're issued a stay-home notice, STAY AT HOME.

"Draconian" as in I don't see it practicable in my country. Not a moral judgment.

Does Japan? Last I saw, they had an inexplicably low curve. Despite not really testing or doing other measures.

Well, I live in Japan and went out properly today for the first time in days, and I can tell you that the R0 is above 1 by eye simply by the way people are behaving.

Social distancing isn't happening much at all, and unless the population is magically becoming immune then there's no way R0 is less than 1. The real questions are whether that will translate into symptomatic and serious cases, and when.

Right. My hypothesis has been that the virus is showing in all places. Something is marking the places with serious cases.

I think the reason it's inexplicably low is that they haven't really been testing.

But there isn't a big spike in pneumonia/ER/ICU numbers either. So it's supposedly not a case of high undetected number of infected running around, laying in hospitals, and it doesn't seem like the government is trying to downplay it either, even if their testing protocol is not extensive enough. (Though they are of course incentivized due to the Summer Olympics.)

Considering the physical proximity of Japan and China (30% of tourists to Japan are Chinese) the fact that Japanese hospitals haven’t been overwhelmed like Italy suggests the virus is not spreading as rapidly there. (Testing may also be a concern but lack of testing cannot hide overwhelmed hospitals).

But why? I have pushed my air quality hypothesis. What other reasons are there.

And you can't just claim social distancing. Unless they have shut down their trains, where people are literally packed in, that just doesn't fly. (So, have they?)

There are a number of thoughts I have, but I'm puzzled as well. My first explanation is that the Japanese are simply more hyegeinic than most other countries I've been to. Fastidious is the word that comes to mind. They wash hands often, wear clean clothes, wear masks or stay home when sick, don't shake hands or touch often.

Second explanation that comes to mind is that they tend to be just healthier than other countries. They have low obesity, exercise correctly and routinely, walk and ride bikes to get where they go, and do all of this even when elderly. The counterpoint to this is that they have a really high smoking population.

Source: I lived there for two years.

The first one could explain why it isn't spreading there. Without testing, hard to know if that is accurate. Reports from other threads supports that it is there, but not severe cases. (Sadly, anecdotes...)

Second is also tougher to square. The risk pool is supposedly older people, per reports from Italy. But, that doesn't seem to square with age profiles of Japanese. So??

One difference could be that old people in Japan are all too often living a solitary existence or not in frequent touch with their family. My wife brought this up last night as I was discussing this thread with her and out of everything I've seen, read, and considered, this seems to be the one thing that could stop it - they were already socially distancing the most vulnerable group.

Still, there's a long way to go for this thing.

Couple of possibilities I've been thinking about:

The virus has been in Italy for a lot longer than they think, and they get close to each other/have actual contact a lot (I don't know if that's actually true, I've never been to Italy)

Maybe they mostly have a particular mutation that is more deadly/infectious

Don't discount the possibility that figures are being massaged in various ways. One is the obvious lack of widespread testing. Another is the reports of people with symptoms being turned away. Then there are the kodokushi[0] numbers which are a clue to how the government already deals with uncomfortable mortality figures - let alone those kudokushi who may die because of the virus - and a over a million deaths a year (I don't know the monthly totals) in which to hide a few hundred (initially) deaths, especially while still in flu season.

In short, I trust the figures here about one step more than ones coming out of China.

[0] https://slate.com/news-and-politics/2015/06/kodokushi-in-agi...

When saying kodokushi, why not just say "old people that die alone"?

Because having a special term for something implies its widespread nature.

I can't square that it has been in Italy substantially longer than Japan. Nor that Italians touch each other more than Japanese. Have you ever seen the videos of commuter trains in Japan?

So, possible, but seems not as likely to be the explanation.

Relying on a particular mutation seems less plausible than difference in air quality exposure that can be measured today.

Don't they wear masks on trains?

Have you seen the trains? No amount of mask would stop some spread there.

Why isn't that the evidence that mask is effective?

It would need testing to show they don't have a prevalence of "mild" cases. Not to mention we should have numbers on how often they wear masks. Last I saw, it was not everyone that did that.

Edit for reference: https://m.youtube.com/watch?v=E7kor5nHtZQ

80% compliance would eliminate flu outbreaks and flu is upper respiratory. https://www.ncbi.nlm.nih.gov/pubmed/30229968

The New Yorker article we are supposedly discussing literally says the coronavirus is not very efficient even in hospital settings.

I am familiar with crowded trains in East Asia. Your video does not have time marker so I assume it is not taken recently.

People don't wear N95 masks here, they wear cheap masks you can pick up in any drug store for just a few coins.

How would an entire country obtain N95 masks and training and proper fitting (it's done by trained fitters) and dispose of them properly, and do that daily? (if not more often)

Every time I go out I see the cheapo ones left in the street because there's a vague notion they should be disposed of "properly" so I don't see this idea working at all.

Public mask wearing prevents the wearer from emitting droplets. You don't need n95 for that. Also please read the article in discussion, this virus is not that easy to transmit, even for hospital workers.

How does an R0 greater than 1 in every country and population the virus is present in square with "this virus is not that easy to transmit"?

I can't do it.

> read the article

Okay, maybe they can square it:

> Luckily, methods were found that protected all the new health-care workers: none—zero—were infected.

> But those methods were Draconian. As the city was locked down and cut off from outside visitors, health-care workers seeing at-risk patients were housed away from their families. They wore full-body protective gear, including goggles, complete head coverings, N95 particle-filtering masks, and hazmat-style suits.

They failed, it was probably the use of "Draconian" that let them down.

I also read the paper you provided, not just the abstract, and it spends a lot of its time talking about N95 masks. Here is from a part it spends on facemasks:

> whereas for the facemasks the efficiency can vary from 10% to 90% (Guha et al., 2017)

Have you read Guha's paper? I've got it here. I have so many problems with someone relying on that paper beyond its narrow applicable scope. I wonder if they've ever worn a mask. I digress.

Additionally (we're back to the paper you shared), you should count how many times "except the low-filtration adult surgical mask" or some combination of those words following except comes up in that paper.

It's also a model and not a study. Let me know when there's a study that shows masks work (the Guha paper mentioned is a study, in a lab, not using people or even a model of a face), in use by the general public, in the kind of settings they wear them, and it's the kind of masks they usually wear.

I assume not recent either. If there is a recent one, I'm interested.

I posted that as evidence masks have not always been worn by everyone.

I'm confused on your 80% compliance number. Are you saying Japanese get 80% compliance on things, and by extension don't have flu outbreaks?

Uhh, show me evidence that China's official numbers and South Korea have r0 above 1 please. It looks like it's finally under 1 right now...

I believe wide-spread use of masks is an effective measure, but i disagree that evidence-based medicine vice Bayesian belief-updating is to blame here. If masks work well, the statistical evidence will come out, regardless of the statistical tribe you belong to.

It came directly from the Surgeon General himself. That’s the part that shocks me. It’s basically someone saying don’t use condoms because it’s not 100%.

I do find it ridiculous that we have ignored practical and common sense measures to protect the most at risk, and instead have decided fo trash our entire way of life and the economy along with it. In the future this will be looked back upon as one of the great blunders in history.

You're right, we should have done both.

You can’t reduce the basic reproduction number (R0) of a pathogen. You can reduce doubling time and similar metrics of the actual spread, but R0 is a fixed number. What you are referring to is the effective reproduction number, which is the rate of spread in a population at it’s current state.

https://en.wikipedia.org/wiki/Basic_reproduction_number

Change in behavior can change basic reproduction number. That is what happened with SARS. Making basic reproduction number smaller is whole point of those curfew laws and of closing shops we now have. It is also the point of washing hands often and keeping distance.

It is defined as "expected number of cases directly generated by one case in a population where all individuals are susceptible to infection". And that is possible to influence by behavior. If no one even meets anybody, no sick person can generate next case. If people live in over-crowded houses, one person will infect many more.

Huh?

"R0 is not a biological constant for a pathogen as it is also affected by other factors such as environmental conditions and the behaviour of the infected population."

Pretty way of saying "Summer heat causes these things to go in remission" by lowering the R0 for a time.

Given that there are cases in hot, humid climates now, I wouldn’t expect summer to save us

From what I've read recently, I agree with this distinction. It's simply a matter of definition. R_0 is the infection rate without any measures taken. Sometimes, R is used for the net infection (e.g. with social distancing).

Read the first sentence of the second paragraph.

citation please

Added. It’s all in the first paragraph.

https://en.wikipedia.org/wiki/Basic_reproduction_number

Maybe you should read a bit further than the first paragraph for your future citations?

"R0 is not a biological constant for a pathogen as it is also affected by other factors such as environmental conditions and the behaviour of the infected population."