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Face masks effectively limit the probability of SARS-CoV-2 transmission

science.sciencemag.org

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Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#371

Post by dang »

alvah wrote: post #261
slver wrote: post #260

Earlier quoted context omitted.

We also saw videos of sick people left to die in Chinese hospitals from their own phone recordings. Is that also propaganda? And no, a video of something that isn’t what we thought it is, is not the definition of propaganda. Propaganda has a goal. This video doesn’t match a single goal China has. If it does name it.

I will politely decline your invitation to name any way the CCP has benefited from the last 14 months of havoc in the West. Feel free to carry on shilling for them.

Accusing others like this is not allowed on HN, and we ban accounts that do it, so please don't.

"Please don't post insinuations about astroturfing, shilling, brigading, foreign agents and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email hn@ycombinator.com and we'll look at the data."

https://news.ycombinator.com/newsguidelines.html

https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme...

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#372

Post by dang »

slver wrote: post #189
alvah wrote: post #142

Earlier quoted context omitted.

"even though the Chinese were very clear about it from very early on" I'm not sure this adds as much credibility as you seem to think. See (for example) - propaganda videos of people dropping dead in the street in Wuhan in early 2020.

Why on Earth are you calling them “propaganda” videos, when China was trying to downplay the pandemic at the time? See, this is one big reason we’re collectively dumb. Everyone and their big conspiracy theories.

Please don't take HN threads further into flamewar. You escalated more than once in this thread. We're trying to go the opposite direction here!

https://news.ycombinator.com/newsguidelines.html

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#373

Post by dragonwriter »

asabjorn wrote: post #366
dragonwriter wrote: post #354

Earlier quoted context omitted.

Without stats on the age distribution of confirmed cases (even before considering the absence of analysis of confounding factors, liking case timing within the pandemic, etc.), I’m not sure how you can say the data doesn’t confirm the conclusion since you don’t have data on the proposed independent variable at all.

Yes, age distribution matters as older people are at higher risk. As some signal for this Florida is USAs old people home, so you would expect that if masks had a large positive mitigatory effect then Florida with its low mask use would do worse than CA and NY that has low mask use. However, we do not see this.

> As some signal for this Florida is USAs old people home, so you would expect that if masks had a large positive mitigatory effect then Florida with its low mask use would do worse than CA and NY that has low mask use.

Again, this has a problem of failing to address case timing and distribution, with CA and NY being hard hit and having COVID into the community before there was much awareness or any policy response (e.g., targeted control measures directed at elder facilities) or personal behavior response or evolution in treatment protocols, which radically changes the dynamic vs. states that weren't hit until after public awareness and health care competence was more advannced.

And presumbaly, you mean “CA and NY with high mask use”, otherwise this argument is nonsense. OTOH, no one has cited any data supporting the “CA and NY are representative of high mask use states while FL (and TX, as claimed in other posts) are representative of low mask use” argument, which seems to be based on stereotyping based on dominant political parties in each state and leanings of political leaders of each party on mask mandates. What data there is on this doesn’t seem to support that this stereotyping accurately reflects mask use, OTOH; i.e., a study on mask use with self-reported data for May through August of last year had mask use as:

AUG: CA 74.6% > FL 71.6% > NY 69.6% > TX 69.1%

JUL: NY 80.6% > CA 74.3% > FL 66.9% > TX 66%

JUN: NY 56.4% > CA 48.7% > FL 45.1% > TX 42.4%

MAY: NY 46.1% > CA 45.2% > TX 43.8% > FL 43.5%

APR: CA 38.1% > NY 36.1% > FL 35.0% > TX 32.4%

And, notably, all four states were in the top half of the country in mask use in all 5 months with data.

https://journals.plos.org/plosone/article?id=10.1371/journal...

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#374

Post by dragonwriter »

beagle3 wrote: post #358
dragonwriter wrote: post #345

Earlier quoted context omitted.

> Personally, I try to only use excess death figures, because case counts are not comparable due to local policies. Deaths are great measure of how bad you’ve been hit overall, but even if they (when you use excess rather than COVID-attributed deaths) are arguably more reliable numbers, they are a much worse proxy when you are trying to compare effectiveness specifically of infection control measures..That’s because…

It is far from perfect; and yet, it's the only metric comparable between different countries, assuming you can trust death counts -- which I do for most countries. It's not a good proxy, but there is no better one that I've found (nor that I'm aware anyone else has found). Every other measure has all of the problems you listed, and in addition it is subject to testing policy differences (including who to test, cycle…

> it’s the only metric comparable between different countries

There are a near infinite array of othere measures besides exceess deaths that are both comparable between countries and not, even approximately, measuring the thing being discussed, which is COVID infections, like GDP per capita PPP.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#375

Post by beagle3 »

dragonwriter wrote: post #374
beagle3 wrote: post #358

Earlier quoted context omitted.

It is far from perfect; and yet, it's the only metric comparable between different countries, assuming you can trust death counts -- which I do for most countries. It's not a good proxy, but there is no better one that I've found (nor that I'm aware anyone else has found). Every other measure has all of the problems you listed, and in addition it is subject to testing policy differences (including who to test, cycle…

> it’s the only metric comparable between different countries There are a near infinite array of othere measures besides exceess deaths that are both comparable between countries and not, even approximately, measuring the thing being discussed, which is COVID infections , like GDP per capita PPP.

Not sure what you are trying to say here. Let's try again.

Are you aware of any other metric for covid infection, comparable between different countries?

Please pay attention to the examples I already gave about how numbers from Israel and the UK make, specifically, "cases" and "deaths from covid" non-comparable.

And remember that I do not dispute that "excess death" is far from perfect. My claim is that -- inherently -- every other measure of covid infection suffers from the same problems that "excess death" does, and then some.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#376

Post by asabjorn »

dragonwriter wrote: post #373
asabjorn wrote: post #366

Earlier quoted context omitted.

Yes, age distribution matters as older people are at higher risk. As some signal for this Florida is USAs old people home, so you would expect that if masks had a large positive mitigatory effect then Florida with its low mask use would do worse than CA and NY that has low mask use. However, we do not see this.

> As some signal for this Florida is USAs old people home, so you would expect that if masks had a large positive mitigatory effect then Florida with its low mask use would do worse than CA and NY that has low mask use. Again, this has a problem of failing to address case timing and distribution, with CA and NY being hard hit and having COVID into the community before there was much awareness or any policy response (…

I tend to trust state policy and political leanings more as an indicator then a self reported study. Can you please dig into why you trust this self reported study on the politically charged mask use question? Especially when the study is performed by academics that is perceived to be too often left-wing activists by republicans and many libertarians? (And according to Haidt have a provably largely left leaning bias)

Self reported results are prone to preference falsification and hidden bias in whom answers. (“Yes, mom, I did my homework” ;) )

Self reported results of politically charged questions are effectively polls. To indicate the problem you can observed how inaccurate polls around politically charged choices has become when compared to actual choices.

The normal problems with self reported results are probably aggravated by how academics, major authorities, media, and tech companies have openly without cover used force to promote the “right” answer and suppressed the “wrong”. The use of force to enforce specific conclusions had been an extraordinary and very noticeable break from western traditions.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#377

Post by gonational »

AshWolfy wrote: post #196
gonational wrote: post #159

Earlier quoted context omitted.

interesting; the same kind of erroneous supposition modeling MO is used to pretend that humans are "cooking the planet" (or is it an ice age? I guess it depends on the decade...).

this is wrong, unrelated, and clear flamebaiting

Should I have preceded my comment with "trigger warning: real information ahead"? I mean, it's now considered "flame be" to state your opinion? Not everybody gets their science from CNN, so not everybody is going to have the same opinion as you. People with different opinions are not trying to troll you by stating their opinions.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#378

Post by jonplackett »

makomk wrote: post #321
jonplackett wrote: post #140

Earlier quoted context omitted.

I really don’t get why this is still considered a conundrum Lots of places have R hovering around 1. If it goes to 1.1 everything goes to shit, if it drops to 0.9. Everything will be fine. So even if masks reduce spread by a tiny amount, even 10% better. That could easily swing you below 1 and save the day.

The trouble is that this doesn't actually work. By using R this way you're assuming a model where every person is equally likely to spread the infection to every other person in the population, which is easy to calculate but what actually happens. In reality people can only spread the virus to those they're in contact with, and (say) a supermarket employee can spread the virus to more people than someone working from…

Ok, makes sense. But why does this make any difference to the crux of my argument? - if that supermarket employee is wearing a mask, they’re going to spread it to less people.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#379

Post by mike_hearn »

jonplackett wrote: post #378
makomk wrote: post #321

Earlier quoted context omitted.

The trouble is that this doesn't actually work. By using R this way you're assuming a model where every person is equally likely to spread the infection to every other person in the population, which is easy to calculate but what actually happens. In reality people can only spread the virus to those they're in contact with, and (say) a supermarket employee can spread the virus to more people than someone working from…

Ok, makes sense. But why does this make any difference to the crux of my argument? - if that supermarket employee is wearing a mask, they’re going to spread it to less people.

R=1.1=everything goes to shit is not a valid inference. R is just the derivative of the case graph. It can and does change on a daily basis, says nothing about absolute levels, and says nothing about how it will evolve over time or what the actual peak levels of infections will be. You can find "exponential growth" in nearly any graph if you want, look at a sine wave for example, and viruses in particular are a curious choice to describe this way because epidemics show S-curve logistic growth, not exponential. It's very confusing to people that it's so often described as exponential because that implies unbounded and very rapid doubling until a day/serial interval before saturation half the population is infected at once, whereas we know that epidemics don't do that in reality.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#380

Post by jMyles »

goatcode wrote: post #365
jMyles wrote: post #364

Earlier quoted context omitted.

I didn't say that there aren't other viruses that cause colds that can be spread by fomites. I said that: 1) There isn't a single virus called "the cold virus" 2) In addition to SARS-CoV-2, there are other viruses that cause cold-like symptoms that are not spread by fomites. Your comment gave the impression that there's a single "cold virus" for which fomite transmission is the primary vector. That's not so. There ar…

Stop again. Then read the link I posted.

I have read the link you posted many times. I am familiar (albeit at an arm's length, as an amateur) with rhinovirus, adenoviruses, coronaviruses, RSV, etc.

At the end of the day, you made a misrepresentation that, taken at face value, gives a false impression that might lead to bad conclusion with respect to control of these viruses.

There are dozens (some scientists believe hundreds) of viruses that cause cold symptoms. Fomite transmission has been reported in a few, though there is scant evidence at this point. In the vast majority, it has not. In some, like the endemic coronaviruses, it has been examined extensively and not found.

It's certainly worth further study!

But your assertion that suppression of fomite transmission - rather than viral interference - is the explainer of splitrocket not having contracted a cold is not well-founded, but might lead to them (or others) believe that this is a positive side effect of surface sanitization.

Now, has norovirus perhaps been suppressed by all the surface sanitization? Maybe. But not colds. The cold viruses appear to have been suppressed by viral interference (with the curious exception of the adenoviruses).

Attempts to suppress fomite transmission come at a significant cost, namely, increased antimicrobial resistance. It's important not to use this method of suppression in places where it will have no effect, such as attempts at population-level control of viruses that cause cold symptoms.

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