Face masks considerably reduce Covid-19 cases in Germany

> And given government advice around the world, it seems pretty clear that masks are understood to do more good than harm.

That's an appeal to authority. It also doesn't mean it's incorrect but it's not evidence of anything.

There cannot be "convincing evidence for mask wearing" for most thresholds of "convincing", can there? Since no clear difference in infections or mortality has been observed between places with different mask rules (and timings of their imposition), the effect must be either very small (in either direction) or none.

> And given government advice around the world, it seems pretty clear that masks are understood to do more good than harm.

Until sometime in March or April, government advice all around the western world was that masks in community settings are ineffective and possibly dangerous (due to improper handling).

Usually when these agencies change position or announce a new position, the decision is accompanied by a properly referenced whitepaper that lays out the evidence for the new position. This hasn't happened here.

The description of S15 gives a plausible explanation of why the effect is much less for some of these city than for Jena. Of course this is speculation but this doesn’t mean that fig S15 disproves the paper’s finding. And for Jena the effect is extraordinarily strong, and well controlled for. I’m not aware of any alternative explanation (to mask-wearing) which could explain this effect, and until I hear such an explanation I consider this strong evidence for the effect of mask-wearing on COVID-19 transmission. This study isn’t the only evidence for the effectiveness of mask-wearing but it’s certainly part of the overall evidence, and I’d like to hear better arguments for calling it “bad”.

Counterpoint: in the US I mostly see people who don't wear masks not keeping their distance and still wanting to shake hands because they simply aren't afraid of Covid at all. The mask-wearing people I see here are more likely to practice distancing and reduced contact.

> Keeping distance seems much more effective than masks. In reality, I've seen that when masks became common place people partially reverted back to flocking together and not respecting a good radius of personal space anymore. Masks probably won't hurt if you need to be close to other people but it would be much, much better to keep the distance in the first place.

I've noticed this when visiting the shops daily when I get my lunch. Before mask were mandated, almost everyone kept each other at a distance. Since mask wearing people have barely bothered.

I've mentioned this to friends on my discord server. Some are from Europe or elsewhere in the UK and they have noticed the same.

The extra care makes a difference. Anedoctally my family did not catch cold or flu since first hearing about the possibility of the pandemy. At least not symptomatic.

> When the situation gets worse then not only the top smartest people but also larger masses begin to take it more seriously to protect themselves, keeping distance, and omitting trips and reducing contacts.

I can confirm it's the same in UK and Italy, people with masks don't keep their distance.

Also it's not only smart people who don't get infected. Think about anyone with kids , anyone doing a job in which they face more people.

It was July the lockdown was lifted and pubs and restaurants were reopened. I think that counts as major.

Mid-August was also half way into "Eat out to help out"[1].

1 - https://www.gov.uk/guidance/get-a-discount-with-the-eat-out-...

> Massive confounding factor here is that starting around April seasonality … was putting massive downward pressure on the epidemic.

That’s wrong, the opposite is the case. The study controls for this by looking at a synthetic control over the same time period, which consists of other populations without mandatory mask-wearing. It’s an observational study so it can’t control for everything but it does control for seasonality, even if “seasonality” isn’t specifically mentioned in the paper.

Anecdotal, but my city made masks mandatory both indoors and outdoors about a month ago with €250 fine for non-compliance. Other measures roughly stayed the same. Prior to that, roughly one in every 88 people were considered to be active cases. Today, that number is one in every 121.

Of course this is just my rough calculation (latest population census divided by the number of active cases), and the number is expected to improve somewhat as the amount of population with antibodies increases, but I'm pretty sure masks help.

>> Masks did not become obligatory elsewhere

I have to challenge this assessment from the article. Masks did become mandatory elsewhere. Mostly in targeted spots in the cities such as the zeil in Frankfurt and Potsdamer platz in Berlin and I can tell you that it is met with strict enforcement and that people are adhering to the rule ardently with very few exceptions. The article and much of the science leaves much to be desired.

It is my opinion that the “all or nothing” pro mask people are actually obstructing the science. Their intolerance to confront or question evidence that is contradictory or unexplained anomalies in the data such as this article is dangerous to actually having the right response to covid leads to nonsensical draconian rules like the California mayor suggesting requiring wearing a mask 24 hours a day and only removing between bites when eating.

Since I seem to get downvoted for adding doubt to the paper in my comment, I move it here:

The study does not look into other east German cities like Weimar[1] or Rostock that showed a similar drop in positive tests without mask obligations. New positive tests in Jena recently reached an all time high. [2]

[1] https://www.corona-in-zahlen.de/landkreise/sk%20weimar/

[2] https://www.corona-in-zahlen.de/landkreise/sk%20jena/

Thanks for the summary, this confirms what I already suspected, which is that these kinds of studies are pretty much useless to correlate anything with anything.

On top of that it seems the study hypotheses for these papers are clearly biased towards proving a positive correlation between infections and mask use, even though one could do exactly the same kind of study in many other parts of the world where infections exploded along with increasingly expansive mask mandates. For example France and Spain, where numbers only started to go down after they went into second lockdown.

No matter what you think of mask effectiveness, cherry picking statistics is bad science, and so far that’s all I’ve seen as far as the ‘masks are effective’ studies go.

How useful masks are depends on so many things. What are they made of is just a small part. Do you know how to use the masks you have? Do you have a beard? Or just a one day stubble? Some masks consists of one layer of fabric and even three-layer masks can't be worn endlessly, they can be washed but not infinitely. Some people wear the mask just covering the mouth, not the nose. Or upside down so the metal strip that seals around the nose is under the chin. I'm no expert in how to use masks but I see dubious things the whole time, both in reality and on TV.

You're right, it should be better.

The Danish study is not good. They're not controlling for mask/no mask, they're controlling for suggestion to use masks (and they didn't even go back and ask "did you wear a mask or not).

In the end it seems people are more worried in publishing hastly prepared experiments/results than worrying about getting to the bottom of things.

> How can we not know based on the shear mechanics of these two entities whether this is effective?

It seems obvious to me that masks have a positive effect. A mechanical barrier is better than nothing. "Oh but influenza" Influenza and Coronaviruses are different

Doctors and Dentists don't use masks because they think it's funny or comfortable

There are different claims -- if one is "frustrated" it's only if one doesn't even attempt to distinguish what's written where. Reading more than just the title in the link you've given:

"The results could indicate a more moderate degree of protection of 15-20%" to the wearer.

"The findings are consistent with previous research. Health experts have long said a mask provides only limited protection for the person wearing it, but can dramatically reduce the risk to others if the wearer is infected, even when showing no symptoms. Preventing the spread to others is known as source control."

Now consider the following: if the "current" R number (the average of how many people are further infected by one infected person) in some environment is 1.2 that still results in the number of infected per day exponentially(!) increasing. Example: after the sequence of 10 infections with R 1.2 there are 6 infected, after the sequence of 20 -- 38, after the sequence of 30 -- 237 and after the sequence of 100 -- 82 million people infected, starting from just one. It is estimated that it takes just a few days for one sequence. Taking that number to be around 3.6 (it doesn't have to be that number, it's just to take some convenient number as an illustration) means that 100 sequences can be imagined as one year. So 82 million in one year.

Now if every wearer is protected only 20%, it can appear to the wearer who doesn't understand math that he should not wear it. However, reducing current R number from 1.2 to 1 means that the number of infected per day doesn't increase at all but remains constant. Example: starting with 1 infected, after the sequence of 100 there are just 100 infected. Using the same convenient number, after one year, still just 100 infected.

That, in turn, means that if everybody wears it, everybody wins: allowing exponential increase of infected will result in everybody becoming infected, whereas the constant number of daily infected could guarantee that most don't become infected before they can be vaccinated.

Not to mention that if the number of infected per day can be kept constant some other kinds of measures (lockdowns with closures, bad for economy) could be completely avoided, especially if it is achieved at some low level. Which means that it can be of immense benefit to the wearer to wear the mask as much as possible even if he increased his own direct protection in some specific situation for mere 20%! Moreover, the benefits are dependent on most others also wearing the mask! If he's doing that alone, than it's in vain -- he alone can't change R for the whole population: his highest interest is to convince others to do the same.

Being willing to understand math and to read carefully helps.

I actually think that you highlighted the wrong date: this paper was put online in June, received for review in July, approved in November, and published in December.

June version: http://ftp.iza.org/dp13319.pdf

Hand-washing and coughing etiquette were emphasised strongly at the beginning of the pandemic, before mask-wearing. But at the moment it actually seems that contact infection is at most a minor — or virtually irrelevant — mode of infection. Hand-washing therefore almost certainly ranks way below mask-wearing in terms of effectiveness^1. As for the rest of the list, social distancing is strongly emphasised but incredibly hard to do in practice. It’s an extremely costly intervention, because it affects the economy both directly (workplaces) and indirectly (restaurants, cinemas …). And yet, notice how many countries still practice strict social distancing rules (albeit inconsistently and often not based on the best evidence).

And as for coughing etiquette, I can’t remember when I last heard somebody cough or sneeze when out. I’m sure it happens (after all, it’s sometimes unavoidable) but it has definitely gotten much rarer. In sum, it’s a very strong claim to say that “masks are a pointless waste of time”, and almost certainly wildly off the mark.

^1 Of course hand-washing should be practiced nevertheless, because it also prevents other infections, notably GI infections. But paradoxically excessive hand-washing also has negative health implications: soap and alcohol destroy the skin’s protective layer and dry it out, and the mechanical action of hand-washing exacerbates this through abrasion, which causes micro-lesions, irritation, and increases the risk of catching infections. And unlike for mask-wearing we actually have very good evidence for this. We don’t yet know the exact consequences, but the NHS has noticed a strong uptick in dermatological conditions since the beginning of the pandemic, some of which are serious. (Here’s a publication on this: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7102542/)

What is your point?

Those charts do not show any information regarding the effectiveness or otherwise of mask wearing.

There is no information about what proportion of the populations actually wore masks, how close people actually got to each other, what the population density and degree of urbanization is, etc.

In Norway we mostly have not had strict lockdowns and have not had compulsory mask wearing until very recently and our infection rates and death rates are lower than most other countries as shown on the charts. But you need to be careful how you interpret that; Norway has a relatively low population density and a large proportion of jobs are of a type that can be done at home. So pretty much everyone who could work from home immediately did so (a lot did anyway). We also have a strong tradition of solidarity; unlike the UK 'We're all in this together!' is not just a slogan.

Our government has also been largely consistent in the advice that it has issued and, with a couple of exceptions, avoided overreacting which means that people are willing to adhere to the rules even though most are just advice and not enforceable.

Most charts from all sources, and especially things like the Federalist, should be taken with a shovel of salt; not because of what they include but because of all the information that is omitted.

Refusal to engage with Gish gallop [1] does not validate the claims you’ve linked. This isn’t “wrongthink”, it’s a sign that you’ve posted a laughably bad source.

[1] https://en.wikipedia.org/wiki/Gish_gallop

Your link is from a bad source. https://en.wikipedia.org/wiki/The_Federalist_(website)

Having actually gone to the trouble of reading all the papers linked in the above article, here's my take:

1. The article attacks a straw man, in that it suggests that masks are supposed to be a cure-all against Covid-transmission. I have not heard this seriously claimed - rather, masks are only one of a range of responses. (Indeed, by far the most important and effective reaction seems to be reducing the number of personal contacts - masks are only intended for those situations where this is not possible.)

2. Masks can only be effective where they are worn. At least in Germany, recent data suggests that most infections are taking place in private settings - where masks are not compulsory (and usually not worn). This could be used to argue both ways: either that the widespread use of masks in public has been successful in reducing infections in the public space, or that the continued widespread infection in private settings means that wearing masks in public is irrelevant. (I do not have the data to meaningfully compare these two claims.)

3. The evidence we have on the effectiveness of masks does seem to be pretty patchy, with many studies showing methodological problems and coming to different conclusions.

4. Generally, the protection effect for the wearer seems to be low or non-existent. However, while not significantly reducing inhalation of virus particles, masks do reduce droplet exhalation (and so protect others in the vicinity of the wearer). I.e., there is an indirect protection effect.

5. It seems to be true that masks are not very effective against aerosol infection (preventing this requires other measures, specifically good ventilation). However, this cannot be used to argue that masks are superfluous, as droplet infection (which masks do help with) is another important transmission vector for Sars-CoV-2.

TL;DR Masks are not a cure-all. They must be used in conjunction with other preventative measures, or they are useless. However, they are probably effective as part of such a larger package.

Germany does not have any strict shutdown. National mobility isn’t limited and all shops are open. The gathering of people is kinda limited, but nobody controls it.

> whether we will ever get back to touching non-family people,

I've been invited to three orgies, with dates TBD ("as soon as this ('gestures around') is over", one says). So maybe we'll have an entirely newfound appreciation of touch.

It will probably take time but we've been here before as human race while knowing how infectious diseases spread. I am a bit worried for the children in delicate age right now who need to learn right now socializing, seeing human emotions, train their immunity systems etc. Adults can have gap year or more, different with children.

The Japanese have had more sensible traditions around (not) touching strangers I think. Wouldn't be the worst thing if those are adopted elsewhere. Hugging strangers like in the US or kissing when you meet people like in some places in the middle east is odd in comparison.

I would not mind. When we get back to office, cubicles will be way more problematic than a handshake.

> Except that this virus seems highly seasonal and spring also came in April!

This effect is controlled for by the study, by comparing Jena to synthetic control groups.

>Where are the "if it's not a double blind study where you isolate a variable, you haven't proven anything" people when we need them!

Yes if only we had a second Earth.