As Wang's study revealed, rates of infection differed between doctors and nurses with [N95] respirators and those without.
Specifically, the authors examined data collected from Jan. 2-22 at six departments within the Zhongnan Hospital. Within the 10-day period, the hospital treated 28 individuals with confirmed cases of COVID-19 and 58 "suspicious" cases. The medical staff in each department followed different safety protocols when treating the patients.
About 280 medical staff in the hospital's Respiratory, ICU and Infectious Diseases departments wore N95 respirators and washed their hands frequently, while about 215 in the departments of Hepatobiliary Pancreatic Surgery, Trauma and Microsurgery, and Urology wore no masks and disinfected their hands less frequently. Although the respirator group encountered confirmed cases more often than the unmasked group — more than 730% more often — no one in the respirator group became infected.
In comparison, 10 people in the unmasked group contracted the novel disease, despite treating fewer infected patients.
"It would appear that N95 respirators, no surprise, protect against health care acquisition of the virus," said Dr. William Schaffner, an infectious-diseases specialist at Vanderbilt University in Tennessee, who was not involved in the current study. The small study is "reassuring in that sense," although there was no reason to think that N95 respirators wouldn't block out the novel coronavirus effectively, he added.
I wonder how this squares with the fact that 2 healthcare workers in California treating a coronavirus patient contracted the disease? I presume they were wearing masks.
One mistake and you got it. Take out mask, touch clothes and then nose or whatever. Procedures are great for the first minute or two...after that unless you're super-trained and do that day in and day out, you'll make mistakes.
They probably were not wearing a mask. It's possible the patient never encountered anyone wearing a mask until the moment that coronavirus was considered as a diagnosis. My basic understanding of this is that it is simply uncomfortable for healthcare workers to wear masks all of the time, and they interfere with patients being able to see their faces (which humans usually like, even when it is a bad idea).
I am interested to hear from anyone in the healthcare field regarding this and if there are any policy changes being put in place, even in regions where coronavirus hasn't (knowingly) spread to yet. From a layman's perspective, it would make sense to require every healthcare worker - particularly in ERs - to immediately start wearing masks.
Having spent considerable time at the hospital in Japan in the last few years, it now seems strange to me. Even my GP, In the 7 years or so that I've been seeing him, I've only ever seen him without a mask once (and I unfortunately get to see him a good 20 times a year :-P). Cultural differences are so strange...
I'm referring to an n95 mask, but I'm betting in Japan workers are just wearing surgical masks. There are plenty of surgical masks in the U.S., of course. They aren't for this purpose, though. I'd assume it's for cultural reasons that surgical masks are worn that much in Japan, probably just makes patients feel comfortable.
Surgical masks are to protect frail patients from your spit and snot, or to keep your spit and snot out of an open body during surgery. Wearing one won't protect you from disease.
That sounds like a study of N95 masks vs no masks, not N95 masks vs surgical masks. Another study reported here on HN compared N95 masks against surgical masks for respiratory viruses and found no significant difference between N95 and surgical masks[0].
That's not really what the study found. It found "there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks". That is not the same as "found no significant difference between N95 and surgical masks".
So the mask group was also competely confounded with being infectious disease specialists? Perhaps there were other precautions besides masks and hand washing that they were taking due to their training, even if not explicitly. Still interesting, particularly given the widespread appearance of "don't bother with masks" articles these days.
Yes - that is what I noticed as well. The two populations have different levels of expertise re: dealing with airborne infectious diseases; different frequencies of hand-washing; and no masks vs. masks. There are just too many confounding factors here to draw a conclusion (in isolation) re: mask effectiveness.
Edit: in addition, the departments used to dealing with airborne infectious disease may have had specialized protocols and policies that the other departments did not have.
I do think that on a personal level, it was probably just more hand washing, the masks to prevent droplets and so on (that is, both groups could have done so, but the infectious disease experts are more likely to do so with every interaction).
"Don't bother with masks" is actually "There is insufficient evidence to show that wearing masks is effective at preventing spread of disease", coupled with "Please don't take away our supply of masks that are for health care workers".
If masks didn't stop the spread of disease, nobody, even doctors, would bother. The problem is that mask usage writ large does not have a cost/benefit point that warrants recommendation by CDC.
That's simply not what I said. The confounding factor isn't hand washing (though that also makes it impossible "model the effectiveness of respiratory masks" as the title says), it's that it's comparing one department to other departments, and those departments surely differ by more than just hand washing and face masks. Infectious disease specialists were trained differently, do different procedures, etc. They see patients with different symptoms and at different stages of their disease.
Essentially the way to treat this is not a study of N doctors but a study of only n departments, which turns it more into an anecdote - albeit a compelling one.
But N95 masks aren't cheap and AFAIK must be disposed after one day of usage. So they must be reserved for the medical workers, while the other can use 3 or 4 layers surgical masks, which should provide adequate protection.
Think about how many disposable gloves the average healthcare worker goes through. Dozens per shift, at least. Those are about 5 cents a pop, easily more than a dollar per day.
after a look at the FDA page on the correct process (don't have access to the original article's references, so i will assume they used the FDA document):
you are dead in the upcoming flu outbreak if you 1. use glasses, 2. sport a beard, or 3. happen to be a kid.
Therefore it is rational for public health policy to reserve high quality masks for medical professionals, regardless of their effectiveness for the general public.
I wonder how many masks they can manufacture a week in this emergency.
In addition to what boulos said, this company makes surgical masks. N95 respirator masks are manufactured in the millions annually by 3M because they are used heavily in the trades.
That said, I don't know where 3M manufactures them, so that supply could be disrupted.
If 80% of people who get this are fine, 20% aren’t fine. Some stats suggest 14% severe, 6% ICU. Someone’s going to have to be taking care of all these categories of severity.
One scenario is home care, with only the severest cases transferred to a medical facility. In that scenario, the “general public” may need to be healthcare providers.
"A total of 81% of cases in the JAMA study were classified as mild, meaning they did not result in pneumonia or resulted in only mild pneumonia. Fourteen percent of cases were severe (marked by difficulty breathing), and 5% were critical (respiratory failure, septic shock, and/or multiple organ dysfunction or failure)."
That's 81% of cases though. Cases are a much more restricted set than "people who get this". Many mild infections will never be noticed or recognised as a case.
The JAMA study [1] is an excellent analysis. However, it in turn was quoting the Chinese CDC statistics dating to February 11th. That dataset is older, fairly small once split into various categories, and likely to heavily skew towards more severe cases given how overwhelmed and underprepared the health system (and everyone else) was early on.
5% severe was the figure seen for Diamond Princess. It's the most well studied group of people (one of few in which they caught all the asymptomatic and mild cases).
People speculate that this is still an overestimate since the cruise may skew old (haven't seen age stats to confirm).
It will also be interesting to see where the Korean church goes as they are also being studied carefully.
I've seen a lot of people suggest not buying the masks when they're in stock at hardware stores so 'hospitals can have some' which I find absolutely hilarious - Just the image of a hospital sending staff down to a Home Depot for some N95 paint masks...
I genuinely think doctors may do that if the government doesn't provide masks, doctors would still want to treat patients and ensure their own safety as best as they can.
I know a story of an ER doctor sending somebody to the hardware store for a tool. My brother also had a regular tool used during his visit to the ER. I don’t think it’s outside the realm of possibility that they simply purchased it at the hardware store. (It was a dremel with a diamond blade to remove his aircraft-grade aluminum ring from an injured finger. Let that be a warning to you about what you put on your finger.)
If you order the masks from the hardware store, then the hardware store is going to order more from the supplier, who gets more from the manufacturer of the n95 filter that also sells them to the hospital mask supplier and fills whichever order comes in first. You are straining the supply chain but it happens a couple notches up, not at the consumer level.
> I've seen a lot of people suggest not buying the masks when they're in stock at hardware stores so 'hospitals can have some' which I find absolutely hilarious - Just the image of a hospital sending staff down to a Home Depot for some N95 paint masks...
But that's not the mechanism at issue. The mechanism at issue is they don't get bought at the hardware store in large quantities, the hardware store doesn't order as many to restock, so their direct supplier isn't willing to pay as high a price to the manufacturer so more of the production capacity is available for other uses.
It's up to the manufacturers and wholesalers how many they sell to the medical industry vs others.
The general public are not the Borg, they don't act with uniformity of purpose. If you tell the public "Don't buy these respirators from the hardware store" and 70% listen, then the other 30% will still buy out all the stock because demand is much higher than supply right now. You can't solve the problem at consumer level.
This. "Don't bother with masks" is actually "There is insufficient evidence to show that wearing masks is effective at preventing spread of disease", coupled with "Please don't take away our supply of masks that are for health care workers".
If masks didn't stop the spread of disease, nobody, even doctors, would bother. The problem is that mask usage writ large does not have a cost/benefit point that warrants recommendation by CDC.
The public generally has mask effectiveness confused (possibly deliberately so, to incentivize).
Masks aren't to protect you from other people.
They're to protect other people from you.
In that sense, yes, even a non-filtering surgical mask is extremely helpful. It helps keep your asymptomatic, virus-laden exhalations, coughs, and sneezes from overly contaminating your local environment.
And that, multiplied by everyone, does make a difference.
The most effective, practical response would seem to be distributing surgical masks, mandating everyone wear them in public, and restricting N95+ for health care professionals working in close proximity to infected persons.
With this disease there is little evidence that asymptomatic people are capable of spreading the disease, and if they are symptomatic they shouldn't be going in public anyway, let alone donning a mask and doing so.
Per that, the correct terminology appears to be nonspecific rather than asymptomatic.
E.g. "According to people familiar with the call, [the index patient] felt tired, suffered from muscle pain, and took paracetamol, a fever-lowering medication."
"“If I was writing this today, I would phrase that differently,” he added.
from Michael Hoelscher, one of the doctors who submitted the errant document. Sweden's Public Health Authority was not too pleased, either.
Most alarming, "Scientists spreading erroneous information about coronavirus have been taken to task around the world, including a researcher with ties to Harvard University in the US who tweeted that the spread of the disease was "thermonuclear pandemic level bad."
I don't have/use Twitter/FB for a good reason, I think it's more virulent than coronavirus.
That's selective quoting from your article. If we're talking about accuracy in reporting, then be objective.
The gist boiled down to (1) the patient in the documented case was not asymptomatic, (2) the symptoms they experienced were pretty mild re: anything that would indicate non-standard flu, (3) it's an unanswered question as to whether asymptomatic transmission is possible.
The answer to (3) from same article being: possibly, but likely only in rare cases and not as the dominant transmission path.
Basically yes. You assume that every doctor may be infected with something. When a doctor is treating a patient, they wear a mask to reduce the risk of disease spreading from the doctor to the patient. It is the same reasoning for why they wear gloves when doing things like operations -- so as not to infect the patient.
Just to clarify, it's slightly more complicated than this.
Surgical masks (note the name) protect _others_ from you. (They are unlikely to do much to protect you from others, but I suppose it might be possible under fairly limited circumstances.)
N95 and other test fit respirators protect _you_ from the environment in general. (I suppose they would also protect others from you, but that's really not their point.)
Gloves protect both parties from each other.
When working with highly contagious patients, medical providers wear additional PPE as well (face shields, goggles, suits, etc).
> The most effective, practical response would seem to be distributing surgical masks, mandating everyone wear them in public, and restricting N95+ for health care professionals working in close proximity to infected persons.
I totally agree and it seems what China is doing to contain the spread of the virus.
If you're leaving your house, or entering a public building, your temperature is measured and you have to wear a mask.
Stockpiles can get quite old (unfortunately I don't have any concrete examples to hand). The US DoD actually runs a shelf life program for testing all sorts of things to find out if they're still good.
To your question, there are many different kinds of masks. For cheap disposables, the foam or adhesive could deteriorate and it would no longer seal to your face properly. Some of the more expensive ones have cartridges; I have no idea what parts might deteriorate and under what conditions, but it wouldn't surprise me at all if they didn't work after sitting on a shelf for 25 years or so. And I have no idea what various filter membranes are made of; chemical stability could conceivably pose a challenge in the long term, particularly regarding what they come into contact with inside the package.
Perhaps. But why does public health policy expect Americans to voluntarily abstain from buying masks, an outcome which is not remotely realistic? It's not like this is an unpredictable situation: it happens in every epidemic. Regardless of masks' effectiveness, enough people believe they are effective to keep them sold out.
If medical professionals need priority, we should have a system to give them guaranteed priority. Then, if there's a remaining surplus, they can be sold to consumers who can buy them relatively guilt-free. (Only relatively, because I suppose the masks could still be shipped elsewhere in the world.) Of course, the government should not force manufacturers to make such a surplus, but it might be profitable for them...
I don't think it's all the individuals that buy them.
There's a class of "entrepreneurs" that like to predict demand in cases like this. For instance, in Poland, masks and respirators are all gone from regular sources now. But you don't see actual people wearing them - instead, if you go to Allegro (our local Amazon/eBay), you'll find a great many sellers selling them by the thousands, at 10x-20x inflated price.
Thanks for this. The US Surgeon General needs to be fired and delicensed from medical practice after his claim yesterday that no one should buy masks because masks don't work. He has no business representing himself as a qualified medical professional.
His statements are such egregious malpractice that they rise to the caliber of extreme negligence and should expose him given his position to liability and possibly criminal charges for contributory homicide.
South Korea is looking at charging church officials with "murder through willful negligence" (https://www.nytimes.com/2020/03/01/world/coronavirus-news.ht...). The reason? They told church members to remove their masks during services as it was "disrespectful to God." Telling people not to wear masks is murder through willful negligence.
Masks don't protect you from others, they protect others from you, and if you are a health professional dealing with infected people from vulnerable populations, or a surgeon asking for a scalpel over an open body, you are going to assume that you are infected and capable of transmitting disease out of an abundance of caution. Masks for the general healthy public is borderline hysteria and affects the medical supply chain.
I wasn't saying n95 respirators don't do anything. They are very effective. I was talking about disposable surgical masks that people are now wearing everywhere.
You should consider reading the scientific study that this entire thread is about.
> In this article, a risk assessment model previously developed in general form was used to estimate the effectiveness of different types of protective equipment in reducing the rate of infection in an influenza outbreak. It was found that a 50% compliance in donning the device resulted in a significant (at least 50% prevalence and 20% cumulative incidence) reduction in risk for fitted and unfitted N95 respirators, high-filtration surgical masks, and both low-filtration and high-filtration pediatric masks. An 80% compliance rate essentially eliminated the influenza outbreak.
> Summary: The study reported 'no significant difference in the effectiveness' of medical masks vs. N95 respirators for prevention of influenza or other viral respiratory illness.
I suspect its also that patient 31 decided that it was ok to run a fever and go to dinner, despite being told that they were at high risk of having the flu.
I did my own little experiment with masks which you can also easily repeat the experiment yourself.
Note that this works on the regular masks you can buy from regular shops such as convenience stores that the general public mostly wears.
Put on the mask in cold weather or a chill room and then take a deep breath and breathe out. You will notice a lot of steam is coming off around the sides of the masks and especially around the nose area where these masks are not sealed. Worse if you cough of sneeze! This is even more so after the mask has been worn for some time and gets soggy.
Next, go outside and ask your friend to light a cigarette and exhale smoke in your face while you take a deep breath through your nose. (Wearing the mask as you would normally do). You will find a lot of smoke gets around the mask, mostly around the edges around the nose.
You can make your own conclusions from there. My conclusion was that these things are mostly toys and the majority of people wearing them either do not fit them correctly or do not change often or both, and they also may be putting too much confidence in them.
Mask fit is important and that's why fit tests evaluation is done for medical professionals so what you're saying has basis.
I wonder if the decreased number of pathogens makes it a different story, though. For instance if you cut down encountered viral load by 95% do you still have equal likelihood of illness?
As I imagine you are expecting to test for smoke in that case by seeing if you can smell it: of course you can smell it, as what you are smelling there is a gas. An N95 mask filters particles larger than some reasonably large size, which hopefully includes giant encapsulated viruses filled with genetic material but is not going to include the odor from smoke which is made up of individual molecules of stuff like syringol. An N95 mask is not some kind of "only oxygen and nitrogen and carbon dioxide (and whatever else you absolutely need from air)" filter: it is just that most scents thankfully aren't harmful, but happen to be correlated with stuff that is.
FWIW, when I wear an N95 mask I do not get steam from its edges (that is either a ludicrously poor fit or you are expecting to be able to breath out too quickly for your mask design), but you also need to remember that breathing out is "safe" while breathing in is not, and yet the pressure in the two cases is very different, so something can be very effective even if it has the issue you are complaining about (and some masks are even designed specifically like that, with pressure vents to make breathing easier so you can exhale quickly without a problem and then pull air in more slowly where the feedback is more clear).
I wear a p3 mask to cycle to work, because I work in central london and don't want to fill my lungs up with crap(as fast).
a P3 mask filters 99% of >0.3 micron particles. It stops diesel fumes, but not smell. I've not tried it with wood smoke, but I suspect that'll fill up the filters much quicker.
you can 100% smell sewers still.
I have recently got some filters that claim to get rid of "troublesome" smells as well, by bundling a carbon filter on the inside. I was forced to by these as everyone had panic bought normal filters. When I replace my filters next week, I'll see if it makes a difference.
> giant encapsulated viruses filled with genetic material
Somewhat tangential, but viruses are actually _really_ small. Some approximate sizes for comparison:
* Pollen: 20 - 35 um
* E. coli: 2 um
* HEPA filter: 99.97% capture at 0.3 um
* N95: 95%+ at 0.1 - 0.3 um [1]
* Sterilizing filter pore size: 0.22 um
* Virus: 0.004 - 0.1 um
Even the sterilizing filter in the lab doesn't remove viruses. I'm not actually sure what mechanics are going on in this case that allow an N95 to protect you.
Masks actually have kind of a funny response curve (see 5th page of linked PDF).
The masks are basically made out of layers of tiny (as small as 1um) fibres that force the air to weave through them to get to you. Larger particles tend to hit fibres on their way through, while smaller ones tend to get pushed out of the way of bigger things like air molecules rushing through and get bumped into the fibres and captured. The things that get though are the ones in the sweet spot of being small enough to make their way around the fibres in the air, but large enough to not simply be knocked out of the path by the air molecules themselves.
The lowest efficiency is around 0.04-0.1um on the models tested (so perfect range for most viruses) but even then they were still only dropping to like 94% effectiveness. I expect “94% effective” is still enough to see a significant different but that’s just my gut feeling.
All kind of moot, though, as coronaviruses (per 4th page of linked PDF) are actually closer to 0.125um, which is veering back to 100% effectiveness. And if we expect that a lot of transmission is happening in droplets, those are much larger and easily caught by the filter.
I asked this same question to a doctor and his response was: The particles of concern are likely to be more than just a single virus cell on its own so an n95 mask does help to some degree.
For something like this, I wonder why the health workers haven’t started using those positive-pressure helmet hazmat suits. Like those from that Outbreak movie.
Anyone have any info on the comparability of COVID-19 to H1N1 in terms of transmission methods since we have official trace data, studies and reports on H1N1? Am having this discussion and being pointed out the fact that H1N1's particulate size is actually smaller than COVID-19 (80-120nm vs 200nm respectively).
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[ 5.3 ms ] story [ 197 ms ] threadAs Wang's study revealed, rates of infection differed between doctors and nurses with [N95] respirators and those without.
Specifically, the authors examined data collected from Jan. 2-22 at six departments within the Zhongnan Hospital. Within the 10-day period, the hospital treated 28 individuals with confirmed cases of COVID-19 and 58 "suspicious" cases. The medical staff in each department followed different safety protocols when treating the patients.
About 280 medical staff in the hospital's Respiratory, ICU and Infectious Diseases departments wore N95 respirators and washed their hands frequently, while about 215 in the departments of Hepatobiliary Pancreatic Surgery, Trauma and Microsurgery, and Urology wore no masks and disinfected their hands less frequently. Although the respirator group encountered confirmed cases more often than the unmasked group — more than 730% more often — no one in the respirator group became infected.
In comparison, 10 people in the unmasked group contracted the novel disease, despite treating fewer infected patients.
"It would appear that N95 respirators, no surprise, protect against health care acquisition of the virus," said Dr. William Schaffner, an infectious-diseases specialist at Vanderbilt University in Tennessee, who was not involved in the current study. The small study is "reassuring in that sense," although there was no reason to think that N95 respirators wouldn't block out the novel coronavirus effectively, he added.
See: https://mobile.twitter.com/skarlamangla/status/1234260334363...
I am interested to hear from anyone in the healthcare field regarding this and if there are any policy changes being put in place, even in regions where coronavirus hasn't (knowingly) spread to yet. From a layman's perspective, it would make sense to require every healthcare worker - particularly in ERs - to immediately start wearing masks.
Surgical masks are to protect frail patients from your spit and snot, or to keep your spit and snot out of an open body during surgery. Wearing one won't protect you from disease.
[0] https://news.ycombinator.com/item?id=22456037
Piling up multiple layers of a completely ineffective barrer does not make it effective.'
It'd be like trying to use layers of netting to hold back the sea.
Edit: in addition, the departments used to dealing with airborne infectious disease may have had specialized protocols and policies that the other departments did not have.
However, one part of your comment stood out to me: the infectious disease units also have higher HVAC standards than say regular areas (e.g., https://www.hfmmagazine.com/articles/3246-studying-airflow-i...).
If masks didn't stop the spread of disease, nobody, even doctors, would bother. The problem is that mask usage writ large does not have a cost/benefit point that warrants recommendation by CDC.
Study: "wearing a mask and washing your hands has been shown to stop infection."
Critic: "This study is worthless, it can show which of these procedures was effective!"
Study: "uh, err..."
Confounding factors would uncontrollable factors that people couldn't implement themselves. People can clearly wash their hands and wear masks.
Essentially the way to treat this is not a study of N doctors but a study of only n departments, which turns it more into an anecdote - albeit a compelling one.
Oh yeah and I don't live in the US so my definition of 'expensive' can be different.
after a look at the FDA page on the correct process (don't have access to the original article's references, so i will assume they used the FDA document):
you are dead in the upcoming flu outbreak if you 1. use glasses, 2. sport a beard, or 3. happen to be a kid.
The US has 30 million surgical masks in stockpile.
The US needs 300 million N95 masks for medical professionals. [1]
[1] https://www.cnbc.com/2020/02/28/us-mulls-using-sweeping-powe...
Therefore it is rational for public health policy to reserve high quality masks for medical professionals, regardless of their effectiveness for the general public.
I wonder how many masks they can manufacture a week in this emergency.
https://www.washingtonpost.com/business/2020/02/15/coronavir...
> Prestige Ameritech, the largest full-line domestic surgical mask manufacturer, was producing 600,000 masks each day but struggling to meet demand.
Even if it’s true that they’re the single-largest manufacturer, they’re definitely not the only one.
Another article suggests that this is three times as much as usual: https://www.yomiuri.co.jp/economy/20200228-OYT1T50288/
Still not enough. :/
That said, I don't know where 3M manufactures them, so that supply could be disrupted.
One scenario is home care, with only the severest cases transferred to a medical facility. In that scenario, the “general public” may need to be healthcare providers.
"A total of 81% of cases in the JAMA study were classified as mild, meaning they did not result in pneumonia or resulted in only mild pneumonia. Fourteen percent of cases were severe (marked by difficulty breathing), and 5% were critical (respiratory failure, septic shock, and/or multiple organ dysfunction or failure)."
http://www.cidrap.umn.edu/news-perspective/2020/02/study-720...
[1] https://jamanetwork.com/journals/jama/fullarticle/2762130
People speculate that this is still an overestimate since the cruise may skew old (haven't seen age stats to confirm).
It will also be interesting to see where the Korean church goes as they are also being studied carefully.
Slip a super-hard, super-thin backer underneath it, then cut? (Aluminum probably being the best scenario, as far as industrial metals go)
In the US, paying thousands of dollars for healthcare, hospitals can absorb the cost of masks increasing from 1 cent to 1 dollar.
There is a shortage, so people in risk groups (elderly people and people with respiratory problems) or people close to those at risk cannot get them.
Second, it increases the price, which caused incidents of people stealing them from hospitals to sell them.
So, in a way, it is more practical then you think.
Not to mention that if it really gets dire, like in Wuhan, then the image becomes less hilarious. (That's why there is the study)
But that's not the mechanism at issue. The mechanism at issue is they don't get bought at the hardware store in large quantities, the hardware store doesn't order as many to restock, so their direct supplier isn't willing to pay as high a price to the manufacturer so more of the production capacity is available for other uses.
The general public are not the Borg, they don't act with uniformity of purpose. If you tell the public "Don't buy these respirators from the hardware store" and 70% listen, then the other 30% will still buy out all the stock because demand is much higher than supply right now. You can't solve the problem at consumer level.
And they respond to demand signals when making that decision.
If masks didn't stop the spread of disease, nobody, even doctors, would bother. The problem is that mask usage writ large does not have a cost/benefit point that warrants recommendation by CDC.
Masks aren't to protect you from other people.
They're to protect other people from you.
In that sense, yes, even a non-filtering surgical mask is extremely helpful. It helps keep your asymptomatic, virus-laden exhalations, coughs, and sneezes from overly contaminating your local environment.
And that, multiplied by everyone, does make a difference.
The most effective, practical response would seem to be distributing surgical masks, mandating everyone wear them in public, and restricting N95+ for health care professionals working in close proximity to infected persons.
https://www.nejm.org/doi/full/10.1056/NEJMc2001468
E.g. "According to people familiar with the call, [the index patient] felt tired, suffered from muscle pain, and took paracetamol, a fever-lowering medication."
from Michael Hoelscher, one of the doctors who submitted the errant document. Sweden's Public Health Authority was not too pleased, either.
Most alarming, "Scientists spreading erroneous information about coronavirus have been taken to task around the world, including a researcher with ties to Harvard University in the US who tweeted that the spread of the disease was "thermonuclear pandemic level bad."
I don't have/use Twitter/FB for a good reason, I think it's more virulent than coronavirus.
https://www.dw.com/en/germany-flawed-coronavirus-study-sprea...
The gist boiled down to (1) the patient in the documented case was not asymptomatic, (2) the symptoms they experienced were pretty mild re: anything that would indicate non-standard flu, (3) it's an unanswered question as to whether asymptomatic transmission is possible.
The answer to (3) from same article being: possibly, but likely only in rare cases and not as the dominant transmission path.
This is pure BS, unless you suggest every doctor is already infected.
Surely you don't suggest the gloves are for protecting the doctor's hands?
Your point is well taken though, I just wanted to clarify for any future readers since misconceptions about PPE seem to abound.
Breaching the skin alone (aka surgery) introduces risks most of us don't have to worry about in our daily lives.
And that's to say nothing of immunocompromised patients (e.g. cancer or transplant).
What's a happy, harmless staph colony on my skin can be very serious for someone else.
Surgical masks (note the name) protect _others_ from you. (They are unlikely to do much to protect you from others, but I suppose it might be possible under fairly limited circumstances.)
N95 and other test fit respirators protect _you_ from the environment in general. (I suppose they would also protect others from you, but that's really not their point.)
Gloves protect both parties from each other.
When working with highly contagious patients, medical providers wear additional PPE as well (face shields, goggles, suits, etc).
I totally agree and it seems what China is doing to contain the spread of the virus.
If you're leaving your house, or entering a public building, your temperature is measured and you have to wear a mask.
Genuine question : how can a mask "expire" ?
To your question, there are many different kinds of masks. For cheap disposables, the foam or adhesive could deteriorate and it would no longer seal to your face properly. Some of the more expensive ones have cartridges; I have no idea what parts might deteriorate and under what conditions, but it wouldn't surprise me at all if they didn't work after sitting on a shelf for 25 years or so. And I have no idea what various filter membranes are made of; chemical stability could conceivably pose a challenge in the long term, particularly regarding what they come into contact with inside the package.
Presumably, dust and stuff will get into the masks over time as well as some breakdown of the materials in the mask itself.
If medical professionals need priority, we should have a system to give them guaranteed priority. Then, if there's a remaining surplus, they can be sold to consumers who can buy them relatively guilt-free. (Only relatively, because I suppose the masks could still be shipped elsewhere in the world.) Of course, the government should not force manufacturers to make such a surplus, but it might be profitable for them...
There's a class of "entrepreneurs" that like to predict demand in cases like this. For instance, in Poland, masks and respirators are all gone from regular sources now. But you don't see actual people wearing them - instead, if you go to Allegro (our local Amazon/eBay), you'll find a great many sellers selling them by the thousands, at 10x-20x inflated price.
His statements are such egregious malpractice that they rise to the caliber of extreme negligence and should expose him given his position to liability and possibly criminal charges for contributory homicide.
South Korea is looking at charging church officials with "murder through willful negligence" (https://www.nytimes.com/2020/03/01/world/coronavirus-news.ht...). The reason? They told church members to remove their masks during services as it was "disrespectful to God." Telling people not to wear masks is murder through willful negligence.
> In this article, a risk assessment model previously developed in general form was used to estimate the effectiveness of different types of protective equipment in reducing the rate of infection in an influenza outbreak. It was found that a 50% compliance in donning the device resulted in a significant (at least 50% prevalence and 20% cumulative incidence) reduction in risk for fitted and unfitted N95 respirators, high-filtration surgical masks, and both low-filtration and high-filtration pediatric masks. An 80% compliance rate essentially eliminated the influenza outbreak.
It's not the only study.
https://www.sciencedaily.com/releases/2019/09/190903134732.h...
> Summary: The study reported 'no significant difference in the effectiveness' of medical masks vs. N95 respirators for prevention of influenza or other viral respiratory illness.
Note that this works on the regular masks you can buy from regular shops such as convenience stores that the general public mostly wears.
Put on the mask in cold weather or a chill room and then take a deep breath and breathe out. You will notice a lot of steam is coming off around the sides of the masks and especially around the nose area where these masks are not sealed. Worse if you cough of sneeze! This is even more so after the mask has been worn for some time and gets soggy.
Next, go outside and ask your friend to light a cigarette and exhale smoke in your face while you take a deep breath through your nose. (Wearing the mask as you would normally do). You will find a lot of smoke gets around the mask, mostly around the edges around the nose.
You can make your own conclusions from there. My conclusion was that these things are mostly toys and the majority of people wearing them either do not fit them correctly or do not change often or both, and they also may be putting too much confidence in them.
I wonder if the decreased number of pathogens makes it a different story, though. For instance if you cut down encountered viral load by 95% do you still have equal likelihood of illness?
FWIW, when I wear an N95 mask I do not get steam from its edges (that is either a ludicrously poor fit or you are expecting to be able to breath out too quickly for your mask design), but you also need to remember that breathing out is "safe" while breathing in is not, and yet the pressure in the two cases is very different, so something can be very effective even if it has the issue you are complaining about (and some masks are even designed specifically like that, with pressure vents to make breathing easier so you can exhale quickly without a problem and then pull air in more slowly where the feedback is more clear).
I wear a p3 mask to cycle to work, because I work in central london and don't want to fill my lungs up with crap(as fast).
a P3 mask filters 99% of >0.3 micron particles. It stops diesel fumes, but not smell. I've not tried it with wood smoke, but I suspect that'll fill up the filters much quicker.
you can 100% smell sewers still.
I have recently got some filters that claim to get rid of "troublesome" smells as well, by bundling a carbon filter on the inside. I was forced to by these as everyone had panic bought normal filters. When I replace my filters next week, I'll see if it makes a difference.
Somewhat tangential, but viruses are actually _really_ small. Some approximate sizes for comparison:
* Pollen: 20 - 35 um
* E. coli: 2 um
* HEPA filter: 99.97% capture at 0.3 um
* N95: 95%+ at 0.1 - 0.3 um [1]
* Sterilizing filter pore size: 0.22 um
* Virus: 0.004 - 0.1 um
Even the sterilizing filter in the lab doesn't remove viruses. I'm not actually sure what mechanics are going on in this case that allow an N95 to protect you.
[1] https://www.ncbi.nlm.nih.gov/pubmed/9487666
The masks are basically made out of layers of tiny (as small as 1um) fibres that force the air to weave through them to get to you. Larger particles tend to hit fibres on their way through, while smaller ones tend to get pushed out of the way of bigger things like air molecules rushing through and get bumped into the fibres and captured. The things that get though are the ones in the sweet spot of being small enough to make their way around the fibres in the air, but large enough to not simply be knocked out of the path by the air molecules themselves.
The lowest efficiency is around 0.04-0.1um on the models tested (so perfect range for most viruses) but even then they were still only dropping to like 94% effectiveness. I expect “94% effective” is still enough to see a significant different but that’s just my gut feeling.
All kind of moot, though, as coronaviruses (per 4th page of linked PDF) are actually closer to 0.125um, which is veering back to 100% effectiveness. And if we expect that a lot of transmission is happening in droplets, those are much larger and easily caught by the filter.
https://multimedia.3m.com/mws/media/409903O/respiratory-prot...