I don't live in the UK, just explaining how I read this comment.
Masks are effortless, but there is also a lot of reason to believe they are not nearly as effective as was sold to people in the early summer.
At some point we get into "just wear a crucifix to ward off the Devil" territory of superstition.
Masks are obviously helpful at preventing transmission of some illnesses, but I've seen enough evidence that Coronavirus spreads via aerosol to not really trust the things.
Mayeb you can post some (preferably peer-reviewed) literature links that show "a lot of reason" to believe this.
> Limitation: Inconclusive results, missing data, variable adherence, patient-reported findings on home tests, no blinding, and no assessment of whether masks could decrease disease transmission from mask wearers to others.
> The recommendation to wear surgical masks to supplement other public health measures did not reduce the SARS-CoV-2 infection rate among wearers by more than 50% in a community with modest infection rates, some degree of social distancing, and uncommon general mask use. The data were compatible with lesser degrees of self-protection.
I don't think any public health experts are saying "wear a mask and you'll be safe", they're saying "if everybody wears a mask, that will slow the infection rate". A study of a community with "uncommon general mask use" does not dispute this.
Finally, I don't think it's clear that a randomized controlled trial is the best method to answer this question. Aside from ethical concerns, you can't give someone a placebo mask. Shouldn't we assume that people will behave differently when they're wearing a mask?
"Although the difference observed was not statistically significant, the 95% CIs are compatible with a 46% reduction to a 23% increase in infection."
The points you are raising about limitations in no way affect the conclusion of the work. Short of putting infected people in a room with uninfected people, there is no ethical way to test the hypothesis that "masks could decrease disease transmission from mask wearers to others".
But since it's pretty unlikely that masks are effective in one direction only, this is the highest-quality evidence we have that they have no effect in one of the two directions.
> Finally, I don't think it's clear that a randomized controlled trial is the best method to answer this question.
A randomized controlled trial is always the gold standard for an intervention of this sort. But yeah, you can't do one for that hypothesis. So you're stuck with something that is fundamentally un-falsifiable. The best you can do is try to do what people have done so far: look at populations, and see if mask mandates make any difference, or ask people who caught Covid if they wore masks, or do similar things within families.
This is called retrospective cohort analysis, and it is low-quality evidence, at best.
> Aside from ethical concerns, you can't give someone a placebo mask. Shouldn't we assume that people will behave differently when they're wearing a mask?
Yes, we should assume that this might happen. It could well be true that wearing a mask makes people be more careless about distancing, for example. This is called "risk compensation", and is a well-known phenomenon in public health.
1. do masks inhibit production of and exposure to aerosols carrying SARS-COV-2? This seems (to me) to me clearly established, and essentially irrefutable.
2. do mask mandates reduce the spread of COVID19? this is an entirely different question, and has almost nothing whatsoever to do with the abilities of masks referenced in (1) above.
Aerosols? It's far from established. In fact, it's a dubious claim, unless you're far more specific about what you mean by "masks". The best laboratory studies show that properly fitted respirators (i.e. as used in hospitals), can reduce aerosol emissions. But few people are wearing respirators, and essentially nobody is fitting them correctly.
Cloth masks? Surgical masks? Cup masks? About the only claim you can make is that they might reduce heavy droplets and then, only by about 30% or so. There's no reason to believe they have any effect on aerosol emission.
Michael Osterholm covered this extensively:
https://www.cidrap.umn.edu/covid-19/podcasts-webinars/specia...
Anyone who has done a mask fitting -- where they put you in a room with vaporized stuff that you can taste to detect leaks -- will tell you how difficult it is to get an aerosol-resistant seal on a mask. The chances that the general public is doing it is 0%.
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Data regarding the “real-world” effectiveness of community masking are limited to observational and epidemiological studies.
* An investigation of a high-exposure event, in which 2 symptomatically ill hair stylists interacted for an average of 15 minutes with each of 139 clients during an 8-day period, found that none of the 67 clients who subsequently consented to an interview and testing developed infection. The stylists and all clients universally wore masks in the salon as required by local ordinance and company policy at the time.
* In a study of 124 Beijing households with > 1 laboratory-confirmed case of SARS-CoV-2 infection, mask use by the index patient and family contacts before the index patient developed symptoms reduced secondary transmission within the households by 79%.
* A retrospective case-control study from Thailand documented that, among more than 1,000 persons interviewed as part of contact tracing investigations, those who reported having always worn a mask during high-risk exposures experienced a greater than 70% reduced risk of acquiring infection compared with persons who did not wear masks under these circumstances.
* A study of an outbreak aboard the USS Theodore Roosevelt, an environment notable for congregate living quarters and close working environments, found that use of face coverings on-board was associated with a 70% reduced risk.
* Investigations involving infected passengers aboard flights longer than 10 hours strongly suggest that masking prevented in-flight transmissions, as demonstrated by the absence of infection developing in other passengers and crew in the 14 days following exposure.
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Taken from: https://www.cdc.gov/coronavirus/2019-ncov/more/masking-scien...
All of these studies were conducted on data from the spring, when cases were declining across the northern hemisphere. How are these places doing now?
DC: up dramatically
https://covid-19.direct/metro/DC
Canada: all-time highs
https://www.worldometers.info/coronavirus/country/canada/
Germany: all-time highs
https://www.worldometers.info/coronavirus/country/germany/
US nationally: all-time highs
California: all-time highs
https://covid-19.direct/state/CA
New York: up dramatically
https://covid-19.direct/state/NY
Boston (where the "unified hospital system" was located): near all-time highs
https://covid-19.direct/metro/Boston
I could go on.
Anyone who attempted to conduct a similar analysis today would have to credibly conclude that masks have no protective effect whatsoever. But who knows...maybe they slightly alter the slope of the curve. It's impossible to tell without a controlled trial.
The german paper is particularly ironic, given that it was published approximately concurrently with a huge increase in diagnosed cases in the same city, which is now at all-time highs for the year:
Absolutely not the case. It would be just as credible, as has been noted by others in the comments here, to suggest that the major cause of spread is unmasked private gatherings.
> But who knows...maybe they slightly alter the slope of the curve. It's impossible to tell without a controlled trial.
I agree that without controlled trials, it is very difficult to tell definitively. That does not, however, translate into "there are lots of reasons to doubt ..."
https://www.acpjournals.org/doi/10.7326/M20-6817
Infection with SARS-CoV-2 occurred in 42 participants recommended masks (1.8%) and 53 control participants (2.1%). The between-group difference was −0.3 percentage point (95% CI, −1.2 to 0.4 percentage point; P = 0.38) (odds ratio, 0.82 [CI, 0.54 to 1.23]; P = 0.33). Multiple imputation accounting for loss to follow-up yielded similar results. Although the difference observed was not statistically significant, the 95% CIs are compatible with a 46% reduction to a 23% increase in infection.
“ Although the difference observed was not statistically significant, the 95% CIs are compatible with a 46% reduction to a 23% increase in infection.”
Also, I quoted this exact line in a comment below, so I'm not sure how you can credibly claim that I'm "mis-representing" something.
Imagine you are standing close to someone at a party who starts talking to you. You immediately notice their bad breath (~aerosols). Now imagine they are wearing a mask, then imagine you both are. How much of the bad breath would you still notice in each case? That's the effect of masks.
So much of what governments are doing in response to this are just cargo cult science. We've had ample time to run proper controlled trials for much of this stuff -- the Danes were able to do so with masks [1], and there was a big study of gyms out of Norway [2] -- it's simply pathetic that our governments mostly haven't bothered.
[1] https://www.acpjournals.org/doi/10.7326/M20-6817
[2] https://www.medrxiv.org/content/10.1101/2020.06.24.20138768v...
Treating R, the number of infections from each case, as though it was the same everywhere is just a way of simplifying the model, but the map is not the territory and we need to be a lot more careful about whether our simplifying assumptions change the overall behaviour of the system being modelled than we have been.
In effect masks buy you a more open environment where people can leave their homes and do more stuff. Further, when locations decide to shutdown that shutdown is more effective.
You're grinding an axe here, but it has little to do with what I wrote.
Did someone claim it was? The name of the game is and has always been suppressing the transmission rate of the virus. Masks are a low impact way to help a little bit towards that goal, nothing more.
Here's what Biden said:
> The first day I'm inaugurated to say I'm going to ask the public for 100 days to mask. Just 100 days to mask, not forever. One hundred days.
Again, he didn't say that wearing a mask is enough, but with the 100-day timeline, reading between the lines, he's saying it will drive down the case count.
It started as just two weeks to flatten the curve, remember.
Could it be ocular transmission?
https://www.ajmc.com/view/can-wearing-eyeglasses-mitigate-co...
Melbourne started their lockdown in winter. Everyone obeyed it. It was strongly enforced [1, 2]. They beat coronavirus. And now they can enjoy their summer.
I live in London. At one point in the summer, our covid rates were lower than Melbourne's. But the UK's messaging was confused and contradictory ("eat out to help out", test and trace was shambolic, rules were not enforced). So no one is the least surprised that it has got out of control again so quickly.
[1] My parents live half an hour's drive from Melbourne. Police stopped every car on the highways to enforce no travel, fined the drivers and made them turn back home.
[2] One party of 26 people got busted ordering KFC to the same address and fined $26,000.
>The Avalon cluster has grown to 38, with 21 out of yesterday's 23 cases linked to it and another two still under investigation.
It isn't fair and might not even be entirely honest to describe this to a (mostly US) audience with a phrase like "numbers seem to be up again".
The trigger for Australia to go back into lockdown would be considered a giant fat ignorable nothingburger in almost every part of the US.
Short lockdown maybe, back to normal soon, not too many other places will be able to brag about that.
We will be able to save all the lives prior to vaccination that nations with less willpower seem willing to spend.
[0] https://mobile.twitter.com/drericlevi/status/132282229786701...
[1] https://twitter.com/drdeannechiu/status/1322834922269073408?...
However there are several contributing factors and it certainly doesn’t come down to mask use as the primary one as mask discipline in the UK hasn’t been bad in my experience.
This is a seasonal disease (the main reason for the UK summer reprieve), and it’s now summer in Australia, and they have also been far better at quarantines and contact tracing and have used this period wisely to get the disease under control. All these factors matter in a response, and the UK has suffered from panic management and a lack of difficult measures at the right time and is now entering the peak season for this sort of virus so things will get worse for a month or two at least, even with a new lockdown.
I'm all for managing the virus spread but if the policies are a piece of meat, in the UK the policies are uncooked in Melbourne they were burnt.
The .au epidemiologists I've heard on NPR have made it clear that what worked in Melbourne was everything they did, including a lockdown and including contact tracing.
As I said - there are other factors here (many more than I mentioned) - that you can't compare countries so easily.
1) hospitals aren’t overwhelmed and
2) less people die unnecessarily
they need binary good/bad cause/effect edicts, like children. state and municipal governments are poorly catering to their own velocity based directives, and the juvenile more simplistic expectations of their population.
I see little to no compliance with customers or shop keepers in places like that.
I also saw lots of maskless partying and social drinking in November.
This is the bigger problem.
I got Covid from community transmission. I quarantined in my house, away from my wife, and wore a mask 24/7.
She didn't get my Covid.
Masks work, but people have to bloody well use them.
Out of curiosity, did she get tested? What about for antibodies?
She didn't get tested for antibodies as the health system has far more important things to deal with right now in the US, unfortunately.
I never got it.
An anecdote means very little, and certainly is not evidence that masks work without controls for every other thing that might have prevented you from getting infected.