New paper: a critical review of cloth masks in preventing Sars-CoV-2 transmission

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Amity Island

Amity Island

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Amity Island said:
The most well written and referenced paper seen to date. Well written and balanced in opinion, giving the overall conclusion that:

“More than a century after the 1918 influenza pandemic, examination of the efficacy of masks has produced a large volume of mostly low- to moderate-quality evidence that has largely failed to demonstrate their value in most settings.”

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A first of its kind global study into non-pharmaceutical personal preventative and social measures to help control the spread of SARS-CoV-2 has shown that the most effective of the current measures is mask wearing which can cut the incidence of Covid-19 by 53%.



https://www.theguardian.com/world/2...ost-effective-way-to-tackle-covid-study-finds



https://www.bmj.com/content/375/bmj-2021-068302
 
Amigo said:
A first of its kind global study into non-pharmaceutical personal preventative and social measures to help control the spread of SARS-CoV-2 has shown that the most effective of the current measures is mask wearing which can cut the incidence of Covid-19 by 53%.



https://www.theguardian.com/world/2...ost-effective-way-to-tackle-covid-study-finds



https://www.bmj.com/content/375/bmj-2021-068302
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It's really hard to rule out confounding factors, though. Since 53% is way higher than other estimates, I'd tend to regard it with some scepticism. And it likely doesn't relate to UK use of masks (for example "masks" in Germany are about FFP2/FFP3 type high quality masks, not the (maybe) 2 or 3 layer cloth masks that we're recommended to use).

This suggests the number (from the paper) ought to be closer to 10% (95% confidence interval 1%-18%):

https://twitter.com/x/status/1461325657653317640

And on the Cato paper:

https://twitter.com/x/status/1459254891818459136
 
Bruce Stephens said:
It's really hard to rule out confounding factors, though. Since 53% is way higher than other estimates, I'd tend to regard it with some scepticism. And it likely doesn't relate to UK use of masks (for example "masks" in Germany are about FFP2/FFP3 type high quality masks, not the (maybe) 2 or 3 layer cloth masks that we're recommended to use).

This suggests the number (from the paper) ought to be closer to 10% (95% confidence interval 1%-18%):

https://twitter.com/x/status/1461325657653317640

And on the Cato paper:

https://twitter.com/x/status/1459254891818459136
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They both seem to be rubbish, pretty much. Depressing!
 
I think one huge variable is how the masks are worn as many go for the under nose or chin warmer style.. Another is that many home made ones are barely fit for purpose not sealing properly in many areas.

I have had Covid and it was very unpleasant. My view is that if they reduce transmission by 20% or 90% it is a reduction which means reduced pressure on the NHS and lives saved. I would make them compulsory tomorrow with on the spot £100 fines!
 
Mask wearing has vastly reduced near me since it was no longer mandatory.

Alongside that many of the restrictions were lifted.

Cases rose.

I can't tell which (if any) of the myriad elements may have been involved in that association.

I confess I haven’t read either paper. I am not really particularly interested to. I recognise that cloth mask wearing will not fully stop me spreading the virus if I have sars cov 2 asymptomatically. The fit is not sufficient. The material is not fine enough. The virus itself is exceedingly small.

I still wear my mask in shops, though no longer while moving about in pubs (which always seemed a bit niche to me).

I think the understanding has shifted more towards an airborne transmission than spread by droplets (and yet hand washing is still a mainstay of advice).

But

When you submit a lateral flow/PCR for sars cov 2, you don’t breathe into a tube, you rub a swab up your nose and back of throat to gather some of the fluid there (in which there is virus).

And when I wear a mask it gathers water vapour, and larger droplets if I cough or sneeze.

Which is sufficient to suggest to me that wearing a mask would prevent some viral material from escaping a person carrying the infection.

I don’t really need any more certainty than that, so the precise percentages hold no interest. I’m not expecting a mask to stop everything, or to be enough on its own. But it will stop something - even if not very much. And it is no great inconvenience to me to wear one. So I carry on. Not to protect myself, but to protect others from me.
 
I’m not sure I find your graph (which I think you have posted before) very helpful in my thinking @Amity Island

If anything it more underlines why mask wearing was introduced at that point. There’s a lag in the timing of several weeks between a person contracting the virus, becoming infected (with or without symptoms), spreading the virus to others, the virus incubating and multiplying in them, them beginning to spread it… and so on. And the more people that have it, and are spreading it the longer the ‘oil tanker’ takes to slow down and change direction.

Cases were rising steeply. And finally the natural government resistance to mandating people to wear masks no longer seemed tenable. But any positive effect of introducing the masks (which is likely to be modest) would take a while before it showed any impact.

Just my thinking. And I’m well aware my confirmation bias towards the potential positive impact of masks is going to be filtering my view of the graph. Thanks for sharing it though.
 
Amity Island said:
The beneift is negligible and if anybody wants to wear a mask please do so, I think in certain situations, wearing a mask is more appropriate like on a bus train etc.
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Conversely, the cost of wearing a mask (for limited periods) is negligible, and the benefit (whatever it is) is primarily for everyone else. So as a public health measure, it's not that appropriate for relying on personal judgement. (The exception would be good masks which really do protect the wearer. Vulnerable people certainly ought to be wearing those in some places.)
 
For at least England it's all moot. I really can't see the government reversing their choices on face coverings. I'm not quite sure what they'll do if things get bad later in the winter, but I'd guess it would be more along the lines of requiring vaccination.
 
This discussion is only relevant to England. The other devolved governments have always differed. If any of you watch Frankie Boyle’s comedy show which is now filmed in Scotland, you will see every member of the audience wearing masks. That is because the rules on wearing masks are different. Watch Question Time and nobody is wearing masks. And that is why everyone at the COP26 event in Glasgow were wearing masks, because of the local rules.
 
Although 3x vaccinated wife & I still wearing masks in shops public places, will do for as long as covid is rampant.
 
Amity Island said:
Well said @everydayupsanddowns I'm much of the same opinion. The benefit is negligible
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LOL! Interesting when you try to write how you feel about a complex and nuanced subject in a balanced way, and it is interpreted as saying almost exactly the opposite of what you meant! :D

What I meant was, I can’t believe masks have no effect (or even a negligible effect) and since they have some positive effect (estimates vary), I believe they are worth keeping as part of the anti-covid measures. 🙂

Amity Island said:
I've attached a longer graph showing case numbers during the entire year. You can see that when mandatory mask wearing was brought in (in England on the 15th June (for NHS and public transport) and extended on 24h July (for shops)), cases were already near their lowest ever, it was only after masks were brought in we see cases rising exponentially. No significant drop in case numbers or even a flattening out can be seen.
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Ah yes, that is interesting!

Do you think these might have had an effect?

1637355775377.jpeg
 
Amity Island said:
What is clear though is that masks don't protect the wearer and masks can only help others if the person wearing it is infectious.and they are within proximity to someone who has no immunity.
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Yes my understanding has always been that I wear my mask to protect others, and they wear their masks to reduce the risk of them spreading sars cov 2 to me. I believe there is evidence of some modest protection inferred on the wearer, but the majority of the effect is on stopping you spreading virus particles if you have it but don’t yet have symptoms.

Interestingly this thread encouraged me to go off for a reminder as to the timing of the introduction of mandatory mask-wearing in shops. At the time, the move was described as ‘muddled and slow’ by the opposition, and one Tory MP said it was an “outrageous imposition”.

The government’s explanation as to the timing seems to have revolved around a few factors including: evolving and increasing WHO evidence of the effectiveness of masks in preventing transmission in enclosed spaces, a desire to provide reassurance to shoppers, and the disproportionate level of infection / cases among shop workers / cashiers.

And of course we don’t have the graph to compare if mask wearing hadn’t been introduced - which may have shown even steeper rises and case numbers?
 
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