Modeling the effectiveness of respiratory masks in reducing influenza (2018)
ncbi.nlm.nih.gov
ncbi.nlm.nih.gov
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.
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.
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.
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.
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.
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.
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...