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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

#341

Post by teleforce »

incrudible wrote: post #289
teleforce wrote: post #287

Earlier quoted context omitted.

Based on the design and capability, I doubt Dr Wu original mask back in the pandemic was even close to N95 mask in filtering the air probably closer to the surgical mask of today, if not worst. The N95 as we know today was invented just recently in 1995[1]. Even with its rudimentary design, Dr Wu's mask had managed to save many lives back then, and in my opinion surgical mask of today will be similar if not better th…

> Based on the design and capability, I doubt Dr Wu original mask back in the pandemic was even close to N95 mask in filtering the air probably closer to the surgical mask of today, if not worst. Surgical masks are not designed to filter air, they are designed to prevent droplets from exiting the mouth and contaminating the surrounding - especially an open wound like you'd have during surgery. Hence, it's called surg…

I am not convinced that Dr Wu's mask during the Machurian epidemic is closer to N95 quality than our surgical mask with various ASTM rated level 1, 2 and 3 standards. If you have any credible references with scientific evidences to the actual quality of his original mask, I'd genuinely like to know.

Personally I will take any protection that I could wear to mitigate and prevent the virus transmission to and from myself than using nothing, since Covid virus is known to be transmitted thru both airborne and bodily fluids including saliva[1]. Like they always mentioned "every little helps". There is also a popular old saying, "no rattan, roots will do" .

[1]https://directorsblog.nih.gov/2021/04/22/study-demonstrates-...

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

#342

Post by jMyles »

andrew_ wrote: post #9
splitrocket wrote: post #3

Not that this will settle anything. Anecdotally, I've not gotten even a slight cold while being socially distanced while consistently masked.

My 2yo would like to sneeze on you and flip that anecdote on its head.

I'm not sure which explanation you are seeking to flip, but a sneeze can be cause by an adenovirus, which were apparently not suppressed this year as the influenza viruses and other four endemic coronaviruses were.

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

#343

Post by jMyles »

goatcode wrote: post #73
splitrocket wrote: post #3

Not that this will settle anything. Anecdotally, I've not gotten even a slight cold while being socially distanced while consistently masked.

>got a cold That's because the cold virus is spread by surfaces, and you likely touched something with it, then scratched your eyes. You can be 80 miles from someone, but if you touch something he touched, you're potentially getting his cold.

> That's because the cold virus is spread by surfaces

Stop. There is no one virus called "the cold virus", and several of the viruses that do cause colds (including, for example, the other four endemic coronaviruses) are not known to spread by fomites.

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

#344

Post by lixtra »

chimprich wrote: post #318
lixtra wrote: post #311

Earlier quoted context omitted.

If masks turn out to be ineffective, the cost of having them recommended is reduced reputation and authority. Would you take security advice from Bruce Schneier after he proposed you to cover your keyboard in snakeoil because it might protect against computer viruses (and if not, there is not much damage)?

That's an absurd comparison. Regardless of how well they work in practice, there's a clear theoretical reason why masks could/should work: they catch salivary droplets containing the virus. Covering your keyboard in oil is not even theoretically going to affect your computer's susceptibility to computer viruses.

That’s the difference between theory and practice.

In practice the snakeoil may prevent you from using your computer more frequently and therefore result in less infections.

In practice I observe a lot of people fumbling out unwashed pieces of cloth from their pockets and placing them in their face, hoping it would preserve their respiratory health.

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

#345

Post by dragonwriter »

beagle3 wrote: post #270
dragonwriter wrote: post #254

Earlier quoted context omitted.

Miami-Dade County, FL has a little under half the cumulative confirmed cases as Los Angeles County, CA (500K vs. 1.2M) with a little over a quarter the population (2.7M vs. 10M), for a much higher per capita rate. So...how is it a counterpoint? (Case numbers from usafacts.org.)

I don’t know the details here, but in the Israel vs Sweden comparison, absolute numbers favor Israel (7000 vs 14000 dead) but age normalized are the same (Sweden has about twice as many >60), and in European normalized excess death measures from Oxford, Sweden is at 2% and Israel at 6% Personally, I try to only use excess death figures, because case counts are not comparable due to local policies. E.g. once vaccinati…

> 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 they are extremely sensitive to when a region was hit during the pandemic (because we learned a lot about treatment over time), geographic distribution and time concentration of infections compared to local healthcare infrastructure (was treatment capacity exceeded anywhere, and by how much for how long?), as well as the population age distribution that you can try to adjust for by age normalization.

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

#346

Post by bagacrap »

vondur wrote: post #88

I don't know. We had some of the highest mask wearing percentages in the country here in Southern California, yet some of the highest infection rates in the world. Something isn't adding up here. I'm guessing if everyone had N95 masks, we would have seen lower numbers however. I don't think the average cloth masks that people are wearing are very effective.

how do you measure mask wearing percentages? Socal seemed to have a lot of unmasked private gatherings throughout the pandemic. The draconian lockdown measures just pushed the spread underground.

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

#347

Post by j4yav »

piva00 wrote: post #310
j4yav wrote: post #257

Earlier quoted context omitted.

Wasn’t it more a result of tribalism? Even before the masks were really a topic it became quite important politically for the pandemic to be real or not, depending on which group you hoped benefitted politically or not. From the outside it looked like everything more or less flowed from that starting point, and then everyone picked their positions and favorite realities from there.

No. And I say that due to my experience here in Sweden, with the same message spread around about masks. I understand why the government did it in the beginning of the pandemic, to save PPE from shortages, to avoid people using masks and getting a false sense of security, etc. Still, it created a lot of distrust when the message changed a few months ago, it wasn't a tribalist issue and I can completely understand how…

Interesting, thanks for sharing. How do you get to a high correlation between mask usage and political party in that scenario, though? If the underlying factor is truly inconsistency from the CDC rather than tribalism then (I think) you wouldn’t expect that.

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3664779

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

#348

Post by asabjorn »

dragonwriter wrote: post #256
asabjorn wrote: post #245

Earlier quoted context omitted.

> The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby. If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)?

> If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)? They...don’t (leaving out NYC because the other three things are large, diverse states and NYC is a single large city): California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population Florida 2.3M cumulative cases & 3,007 case/day 7-day a…

NY (not NYC) cumulative cases is 2m and population is 19.4m, so about 10.3% of population [source: google coronavius stats].

> California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population

Its 3.77M, so about 9.5% of population.

> Texas 2.9M cumulative case & 2,034 case/day current 7-day average vs. 29M population.

That's 10%.

> Florida 2.3M cumulative cases & 3,007 case/day 7-day average vs 21.5M population.

That's about 10.6%.

> FL and TX are worse on per capita cumulative cases, and much worse on current per capita new cases than California.

With the total cases being about the same so this does not support your conclusion that masks "drastically reduce spread".

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

#349

Post by asabjorn »

johbjo wrote: post #313
dragonwriter wrote: post #256

Earlier quoted context omitted.

> If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)? They...don’t (leaving out NYC because the other three things are large, diverse states and NYC is a single large city): California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population Florida 2.3M cumulative cases & 3,007 case/day 7-day a…

Also consider age distribution/population density in areas you compare. Death rate is exponential in age, so small differences in age distribution gives big differences in relative deaths.

Death rate to confirmed cases is TX 1.7% (51k deaths over 2.9m cases), Florida 1.56% (36k deaths over 2296 cases), CA 1.64% (62k deaths over 3.74m cases) [source: google coronovirus stats]. So data does not confirm your conclusion.

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

#350

Post by asabjorn »

kelnos wrote: post #271
asabjorn wrote: post #252

Earlier quoted context omitted.

> I suspect that in locations with a higher prevalence of masking the population is generally more vigilant: more hand washing, more social distance, stay at home when ill, avoid obviously ill people, and so on. May be a case of correlation, not causation. The states with the highest mask use (NYC, CA) has some of the highest covid positive rates, so the data does not seem to back up your assertion.

You seem to be repeating this in several comments, but that's just not true. CA's total per-capita case counts and recent new-case rate is lower than, say, both Texas and Florida. NYC is not a state, so you can't directly compare it.

The confirmed cases to population is 10.3% for NY (not NYC- 2.08m cases to 19.4m population), 9.5% for CA (3.77m cases over 39.5m population), 10.1% for texas (2.93m cases over 29m population), 10.6% for Florida (2.29/21.48).

Deaths to confirmed cases is about 1.6% for all except NY. NY death to cases is 2.6% (52k deaths over 2m cases). However, this way of computing deaths is only indicative as you do not capture untested cases.

> Florida 2.3M cumulative cases & 3,007 case/day 7-day average vs 21.5M population.

That's about 10.6%.

> FL and TX are worse on per capita cumulative cases, and much worse on current per capita new cases than California.

With the total cases being about the same so this does not support your conclusion that masks "drastically reduce spread".

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