Hacker News Reader

Comment by lhl | Hacker News Reader

It’s true that Japan has done many non-optimal things, but the biggest difference from the west IMO is that there has been close to 100% mask usage (eyeballing in Tokyo, about 95% surgical masks) for over a year now. Any Japanese who see things like Idaho’s recent mask burning protests are simply bewildered. Of course, people take their masks off when eating out, but still keep them on while ordering and waiting for food, and the “3C’s” messaging has also focused on improved ventilation in buildings and vehicles while this was ignored in many other countries (seems like pretty basic stuff for a highly contagious respiratory virus).

The mix of policies (specifically the lack of testing and rapid testing) has led to Japan being one of the least effective East Asian countries in containing COVID (just compare it to Taiwan, South Korea, or China), but leagues better than the west. Some of that calculus has changed with B117 and other variants, especially those that spread more with children, you’re seeing now reports of community spread of these variants in schools being reported (Japan’s focus in cluster tracing, while it has been overwhelmed at times I believe can also be given a lot of credit for keeping numbers much lower than they would otherwise be).

View on HN

> the biggest difference from the west IMO is that there has been close to 100% mask usage (eyeballing in Tokyo, about 95% surgical masks) for over a year now

I had something in there about this, but deleted it because I thought it was distracting from the main point, and any mention of masks brings out the politics.

That said: I see an...well, let's just call it interesting...number of Japanese people socializing in small restaurants, bars, etc. without wearing masks. Likewise, it's really common to see TV talent wandering around Tokyo wearing no mask, or one of those teeny tiny transparent plastic chin-visor things [1]. I see it literally every day (via facebook, instagram, LINE, etc.) Try to wear one of those in a grocery store in San Francisco or New York. I dare you.

Is this "proof"? No, of course not. But I do roll my eyes when people present Japan as a magical masking wonderland. The truth is more complicated. Just like New York or SF right now, people walk around with masks on the street, where they do ~no good. They then go inside to tiny, crowded bars and restaurants...and take off their masks. At the very least, this is all a bit overblown.

(If you want my speculation, I think the fact that Japanese people have a culture of being quiet probably plays a bigger role than masks. There aren't a lot of people talking loudly in crowded public spaces. Except for bars and restaurants, people are quiet and respectful of shared space. One of the things I loved most about living there.)

[1] https://p.globalsources.com/IMAGES/PDT/BIG/614/B1176919614.j...

> I see an...well, let's just call it interesting...number of Japanese people socializing in small restaurants, bars, etc. without wearing masks.

Same in Seoul. When discussing this matter with friends located elsewhere, they seem to have difficulty believing this, but every cafe and restaurant will have 90%+ of visitors talking without masks after they finish eating until the time they leave. (Those sitting alone quietly reading a book will wear masks, ironically they’re the smallest threat.) Government has been dealing with this by temporarily forcing franchised shops to shut down, and later restricting working hours of coffeeshops and restaurants (a few in the area, mostly franchises, had to close forever), while people more or less continued to behave the same way throughout the pandemic if they manage to find a place open for eating in. At a cafe or a restaurant, it almost seems like it’s socially unacceptable to be conversing with a friend whilst wearing a mask.

This makes little sense to me, especially since walking outdoors without a mask is perceived as taboo[0]. At some point public parks had sitting spaces and grass non-figuratively taped over with signs preventing people from gathering in fresh air, all the while restaurants stringing along park edges were visibly chock full of people gathering to talk indoors (I’ve taken a few photos as it was a shocking sight). Initially this made me furious as I saw pure malice in that arrangement; later someone told me that the government “just” wanted to not be liable for infections that occur in spaces under their direct jurisdiction. This persisted for months until people gradually started ignoring the tape in the park.

The only place where everyone reliably wears a mask is buses: bus drivers monitor the cabin and seem to take this matter very seriously.

If I’m to speculate, the reason it’s comparatively fine now is thanks to extensive testing and seemingly working contact tracing measures.

[0] You’ll be judged unless you are stationary and smoking, in which case no one would bat an eye. Go figure!

When infection rates spiked, did Korean people reduce the time they spend maskless in public indoor spaces?

Are Korean people more likely to wear a mask in public when they're feeling sick?

> When infection rates spiked, did Korean people reduce the time they spend maskless in public indoor spaces?

I’d say “yes but not quite to degree people seem to expect”.

First, I don’t have direct evidence as I stopped working from an office a while back, but I believe that within office spaces—which fall under semi-public indoor spaces I suppose—being maskless outside smoking areas is not tolerated.

Second, I believe people have on average reduced the time they spend in indoor spaces (maskless or not) other than their homes or work, since eating out slightly lost popularity relative to getting food delivered since the pandemic started. (Still, many people do eat out in groups and restaurants have rarely been empty, only shut down during peaks.)

> Are Korean people more likely to wear a mask in public when they're feeling sick?

You’d be hard-pressed to find people being visibly sick in public, this seems to carry a strong stigma. I could maybe spot 1–2 people in a week sneezing/coughing outdoors or in a cafe, and this won’t be someone in a chatty maskless group. Transmission by asymptomatic carriers is the one that concerns me.

I think the above equally applies to Koreans as it does to foreigners residing in Seoul.

(Above is from my perspective only, could be biased.)

Everything you've written here is consistent with what I'm seeing out of Japan (not terribly surprising, but it's good to see confirmation that I'm not getting a biased sample).

Based on your replies, my own experience living in Japan, conversations with Korean people, and conversations with my sister who is living in Korea, I believe the the reduced spread of the virus in Japan & Korea compared to western countries is because of many behavior differences of Japanese & Korean people. For example:

1. In USA, few restaurant workers have job security. If they take sick leave, they lose their jobs. So when they get sick, they go in to work and spread it. In Japan & Korea, most restaurant workers can stay home when sick.

2. In USA, most people don't have the idea of staying home from social events when sick. When they have a cold, they will take medicine to suppress symptoms while they visit family & friends, go to church, etc. This happens much less in Japan & Korea.

3. In USA, before the pandemic, nobody wore a mask while socializing when sick. Even now, it is rare in many parts of the country. In Japan & Korea, wearing a mask when sick in public is expected, like wearing clothing over your underwear. So a Japanese or Korean person who feels a little under the weather will opt to keep their mask on when attending a maskless gathering, but an American in the same situation will likely take theirs off.

4. Smoking was banned in restaurants & bars in Korea in 2015 and Japan in 2020. So most restaurants in those countries still have powerful ventilation systems designed to handle cigarette smoke. They can turn them up to reduce Covid transmission risk. In USA, most places banned smoking in restaurants & bars about 10-20 years ago. Since that time, many restaurant ventilation systems have been replaced or reconfigured to reduce the air exchange rate.

These and other differences add up to a large reduction in virus spread.

I have heard many Americans write essentially, "People are maskless in restaurants in Japan and Korea and there's no spike, so we can do it in my country too and not get a spike." I think this conclusion is incorrect. It is based on incomplete knowledge of the differences between their country and Japan & Korea.

[0] https://en.wikipedia.org/wiki/List_of_smoking_bans_in_the_Un...

What you say in the first part sounds correct, in that visibly sick people could be more likely to be aware of it and stay home or wear a mask than in other parts of the world, but don’t underestimate the pressure to conform. A maskless gathering will hardly have someone standing their ground wearing a mask, regardless (if one is visibly sick one will be unlikely to attend though).

If people here were more aware of the mechanics of spread and asymptomatic carriers, I think the high peaks could have been avoided.

As to ventilation, before it was officially banned many restaurants were already non-smoking. Add to that the incredibly fast churn of restaurants closing, opening and renovating, and you can see there’s no perceptible residue from that period. (I don’t observe particularly strong ventilation in Seoul restaurants or cafes, but to be fair I am mostly comparing to Hong Kong, not US.)

> In Japan & Korea, wearing a mask when sick in public is expected, like wearing clothing over your underwear.

No, this isn't even close to true. I've spent far too many hours crammed into trains, classrooms, offices and bars, next to sniffling Japanese people who were walking around sans masks, to believe this silly narrative. Getting on a crowded train and having a guy repeatedly sniffing his runny nose six inches from your face is practically a running joke.

The Japanese people I know mostly seemed to wear masks to keep their faces warm in winter, and to reduce allergies during the cedar season. Girls would sometimes wear them to hide their faces or to hide a blemish. Maybe some people wore them to prevent disease, but it was far from a universal goal.

> So a Japanese or Korean person who feels a little under the weather will opt to keep their mask on when attending a maskless gathering, but an American in the same situation will likely take theirs off.

This is a great example of stereotyping and asian exceptionalism. If anything, Japanese people are immensely aware of social pressure, and won't go against obvious social cues.

Japan and Korea weren’t hit much by the original SARS in 200x (no confirmed deaths). However, it was a huge deal in Hong Kong (considering the deadliness of the disease and high population density). IMO for an example of strong mask-wearing practices for primarily infection-related purposes one could look there, though I’m willing to be corrected.

> ... to believe this silly narrative.

I interpret that as a personal insult. Let's disagree without insulting each other.

> > So a Japanese or Korean person who feels a little under the weather will opt to keep their mask on when attending a maskless gathering, but an American in the same situation will likely take theirs off.

> This is a great example of stereotyping and asian exceptionalism.

Yes, we're talking about millions of people in aggregate. This requires stereotyping. Stereotyping is only bad when you expect an individual to behave like the aggregate.

> If anything, Japanese people are immensely aware of social pressure, and won't go against obvious social cues.

That's what I was trying to convey with my statement that wearing a mask is expected like wearing clothing over underwear. Your point about people sniffling on the train is compatible with a social expectation of wearing masks when sick. Every society has some non-conformists. The difference is that sick-no-maskers in Japan & Korea are outliers and in many parts of USA they are the majority. This is what I meant about many small differences adding up.

IMO you may be mistakenly attributing Western individualism here. If your friends are not wearing masks in some situation, you may choose to wear one and not fret about it, but not everywhere is like that.

This is not about individual no-maskers, but rather a peculiar social norm to collectively forgo wearing masks in certain situations.

To the folks downvoting: Please explain why you think the questions are not appropriate for this discussion.

Stranger danger.

If you're having lunch with someone, you probably know them well and trust them to have a sense of hygiene. Some random person who sneezes on Line 9 during the morning rush, not so much. Or at least that's how people's minds appear to work.

This behavior seems to be sustainable only because the background rate of infection is so low. It really is vanishingly unlikely for anyone you come across in a coffee shop to have the virus, as most of the cases have occurred in relatively isolated groups like religious cults, prisons, and hospitals.

Good point and new case distribution rings true based on what I heard.

My exasperation mostly comes down to nonsensical norms/regulations where a person safely not wearing a mask outdoors to get fresh air has to fear being judged (or having police called on, I suppose) by the very people who semi-daily engage in active airborne fluid exchange with random strangers sharing the same cafe as their group of friends or coworkers. If I had a say in this, either the former has to be recognized as socially acceptable (2m distance and so on, of course), or the latter has to stop being tolerated. It almost physically pains me to see people getting outside to enjoy a clear day with great AQI, and everyone must be either wearing a mask or smoking.

Oh, and the measure with the parks seems absolutely ridiculous. Never been one to hang out in a park, but seeing groups of friends virtually being ushered by signs from outdoors into a cafe to talk is bizarre.

Good for the country on the testing effort and having things more or less under control, though.

When infection rates spiked, did Japanese people reduce the time they spend maskless in public indoor spaces?

Are Japanese people more likely to wear a mask in public when they're feeling sick?

Do Japanese restaurants still have good ventilation systems, originally installed to remove cigarette smoke before the 2020 indoor smoking ban?

I am skeptical that mask usage is the major factor. The lower obesity rate probably has a larger impact.

https://www.nature.com/articles/s41574-020-00462-1

The comparison was on case rate. Being obese doesn't make you more likely to catch the virus afaik.

Case rates can't be usefully compared between countries because they all have different testing practices. Being obese actually does make you more likely to catch the virus.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7430889/

The study you linked shows that obesity is linked with more severe outcomes, not higher infection rates.

I know at least one study that shows infection rates did not change with co-morbidities, see Fig 6b in https://www.nature.com/articles/s41467-020-19509-y

However I would not be surprised to see slightly higher infection rates mediated by healthier immune systems in healthier folks.

Did you read the article?

"... indicating that SARS-CoV-2 is more likely to enter the human body in obese people as compared with non-obese people."

"Increased ACE2 expression in chronic obstructive pulmonary disease (COPD) patients who are overweight compared to those not-overweight was observed [3], indicating that SARS-CoV-2 is more likely to enter the human body in obese people as compared with non-obese people. "

Not sure why you left out that the study was done on obese patients that also have COPD. You can also check the primary source [3].

"In summary, we have shown increased ACE2 expression in the bronchial epithelium of COPD patients who are overweight compared to those who are not overweight. This may provide increased opportunities for SARS-CoV-2 infection of the respiratory tract. These individuals may be at greater risk of developing severe COVID-19."

Again, that's a hypothesis that makes completely sense, but from your study alone we do not know how much greater the risk is - 0.5% 5%, 50%?

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7276828/

I could see being obese making you more likely to be symptomatic, and hence more likely to get tested and show up as a case statistic

The biggest difference is in the waistlines. As reported just the other day[0]:

> Of the 2.5 million COVID-19 deaths reported by the end of February 2021, 2.2 million were in countries where more than half the population is classified as overweight

Japan is not one of those countries.

As someone who lives in Japan I can tell you that the general population isn't wearing high quality, fitted masks in controlled conditions and using their clinical training to avoid disease transmission, which might provide the conditions that any study done on masks could have the possibility to back. No, there's plenty of cheap, reused, badly fitted, incorrectly worn, regularly touched and inconsistent mask wearing by people who've not had any training in how to limit transmission, which would explain the frequent flu epidemics[1][2][3].

[0] https://www.worldobesityday.org/assets/downloads/COVID-19-an...

[1] https://www.nippon.com/en/japan-data/h00386/japan-gripped-by...

[2] https://english.kyodonews.net/news/2018/01/e609ee653721-flu-...

[3] https://pubmed.ncbi.nlm.nih.gov/28668446/

Obesity does not really explain order of magnitude fewer cases, and obesity is much less of a factor than age for mortality. I can't find the numbers now, but it is better to be younger and quite fat than much older and fit. Japan does not lack people above 85 years where the fatality rate is double digit if you catch the disease.

The only reasonable answer I have seen so far about Japan is that we don't really know. It is certainly true that many people don't wear masks properly in Japan (e.g. every time I get out, even just to combini, I see people not wearing masks on the nose). But is it worth than not wearing one ? I am not sure we really know. I've seen conflicting info there.

Well, problems with obesity might also correlate with older, wealthier populations but they also looked at that:

> The figures are affected by the age structure of national populations and a country’s relative wealth and reporting capacity, but our findings appear to be independent of these contributory factors

It's got links to a lot of other studies (admittedly, I'm yet to read those) but the summaries they give seem to really place the importance on the size of the waistline.

Just looking at your second link, the odds to hospitalized w/ a severe obesity (> 35 BMI) is 2.5 higher than people w/ BMI in healthy 20-25 range

Now, according to https://www.cdc.gov/coronavirus/2019-ncov/covid-data/investi..., the risks of hospitalization in 85+ years is more than 10x the risk in 30-39 year old range.

If we're talking about mortality, it is more than 100x difference between those two age ranges.

It is really not comparable: being old is much much worse than being obese as far as hospitalization/mortality goes w/ covid.

No one is disputing that age is a factor. From the very first line of the foreward:

> As we show in this report, increased bodyweight is the second greatest predictor of hospitalisation and a high risk of death for people suffering from COVID-19. Only old age rates as a higher risk factor.

But if you're really going to compare against age then you'd need to correct for obesity or you're simply including it and possibly compounding any risk.

> the risks of hospitalization in 85+ years is more than 10x the risk in 30-39 year old range.

Is the difference 10x in Japan, too?

The point is (or was) to discern a difference between why Japan has lower cases and/or mortality vs Europe and America. All three have plenty of old people, Japan has the greatest percentage. There is also a marked difference between their average waistlines too.

Japan should have the highest cases and/or mortality of the three and yet it has the lowest. I'm not a betting man and "masks are the reason", without a shred of evidence to back it, isn't going to change that habit, especially given the competition:

> Is this link between COVID-19 and overweight found across the globe? > Yes. > A large number of studies and systematic reviews have found increased risk of severe symptoms from COVID-19 associated with excess bodyweight. The table here gives some examples (pg 14)

And the table really does give plenty of examples. From the US:

> People with obesity more than twice as likely to need hospitalisation and more than six times as likely to need mechanically assisted breathing and more than six times as likely to die following development of COVID-19. (pg 14)

From the UK:

> People with overweight 67% more likely to need intensive care, and people with obesity three times as likely to need intensive care, following development of COVID-19. (pg 14)

…among many others. It continues:

> Taking data from over 160 countries, we find linear correlations between a country’s COVID-19 mortality rates and their estimated degree of overweight or obesity prevalence (pg 15)

and here's the kicker:

> The diagram shows high mortality rates *only* in countries where overweight prevalence exceeds around 50% of the adult population. (pg 15)

Emphasis mine. As to directly comparing Japan and the US and UK, they've added a helpful index:

- COVID-19 deaths per 100,000 population (01/01/2021)

- Adult overweight BMI >25kg/m2 (2016)

- Adult obesity BMI >30kg/m2 (2016)

- Population age over 65 years (%) (2020)

- Per capita Gross Domestic Product $US (2019)

- Healthy life expectancy years (2019) Insufficient physical activity % adults (2016)

- Japan 2.60, 27.2, 4.3, 28.4, 74.1, 35.5

- UK 110.73, 63.7, 27.8, 18.7, 70.1, 35.9

- US 105.68, 67.9, 36.2, 16.6, 66.1, 40.0

As to mask wearing, well, if survey results of real world usage are to be believed, then it really is no contest, as the charts here show:

https://twitter.com/ianmSC/status/1366148529983426560

Edit: formatting. I do like the stripped down approach of HN but would it really be too much to supply a markdown processor, or <gasp> a format guide?

I have heard air humidity cited as one relevant factor, which was also recently brought up as one of the reasons masks may have a protective effect (humidity from breathing collects in there). Something about keeping membranes being healthier in warm, humid air than in cold, dry air?

Agreed, I feel one result of political correctness has been a refusal to acknowledge how much obesity affects every aspect of your health. I used to be morbidly obese and I was constantly sick up until I lost 70 or so pounds and got to a reasonable weight. This also made dating so much easier. I'm going off on a tangent, but if I had to give one piece of advice to any young person it would be to get to a healthy weight. Tons of damage is done to your body for every day you're obese, and it's not always reversible even if you start eating right later.

It's unsurprising countries with obesity epidemics such as the United States have higher rates of covid mortality. There have been several stories where someone in their twenties dies of covid, but until you see the photo you had no idea they were morbidly obese.

If I had to guess I'd say in healthier populations many people may have covid and just shrug it off without necessarily getting tested and adding to case numbers.

> I'm going off on a tangent, but if I had to give one piece of advice to any young person it would be to get to a healthy weight.

Following that tangent, I had a couple of family members turn 16 recently and I wondered what advice I could give them now that they are adults (or, at least, they will certainly believe that to be so! Ah, the folly of youth:)

My thoughts settled on what would basically be me telling my younger self about my regrets or (perceived) failings in life and to avoid them. I then wondered if they'd listen, which I doubt (again, the folly of youth) and whether I'd even be able to put it in a form that they would understand. Rather like me trying to teach them programming before they've opened a terminal or even an HTML file, I can't tell them the deepest insights until they've done quite a bit and failed quite a bit too.

I haven't decided on my advice yet or if I should, but yours sounds good. Still, it's hard to realise what unhealthy means when you're young and fit, even if it's only relative to your older self.

A big part of being 16 is thinking that you know everything.

But to be perfectly blunt, to a young man I would just tell him girls aren't going to really like you unless you get down to a healthy weight. That's the only thing that will probably get though.

Co-morbidities certainly have an impact on outcomes and explains why the IFR is much worse in certain parts of the world but IMHO it doesn't fully explain the magnitude lower attack rate/spread (50-100X worse in the US). That's still a mystery for which there are many plausible contributors, but I don't think it's so easy to just say it's obesity. In the US, this n=5700 NYC study showed 41.7% were obese [1] (not so different from the current US adult obesity rate is currently of about 42% [2]).

Note that age is actually the most reliable predictor for hospitalization and death with COVID-19 [3][4] although you can make more accurate estimates with some other factors as well [5]. Note, based on the age-stratified pyramids, Japan's expected IFR sits right at the top [6], so even if you discount the undercounting of hospitalizations and deaths, there's still a huge disparity to make up.

BTW, your argument on flu outbreaks actually lends credence that the mask mitigations have been extremely effective. Here's a recent NHK report on the flu numbers this year [7]: - "The number of patients with seasonal flu in Japan was below 100 during the first seven days of February. That's far below the levels seen before. ... Usually, seasonal flu peaks at this time of year, with the number of flu patients per week ranging between 100,000 and 200,000 people." Flu cases are 1000-2000X less than normal.

I'm in Tokyo myself and paying close attention to how people are behaving (and comparing it to the footage and media I'm seeing from the US and other countries) and there's a huge difference in behavior from what I've seen over this past year. If you're disappointed by how the general population behaves here, I suspect you'd be horrified/stupefied by what's going on in the rest of the world. My conclusion is that on a population/public health level, it actually doesn't take all that much effort to contain the spread of the virus (elimination is much harder, although several countries have shown that it can be done, and have reaped the economic & social benefits of doing so).

[1] Richardson, Safiya, Jamie S. Hirsch, Mangala Narasimhan, James M. Crawford, Thomas McGinn, Karina W. Davidson, and the Northwell COVID-19 Research Consortium, et al. “Presenting Characteristics, Comorbidities, and Outcomes Among 5700 Patients Hospitalized With COVID-19 in the New York City Area.” JAMA 323, no. 20 (May 26, 2020): 2052. https://doi.org/10.1001/jama.2020.6775.

[2] https://www.cdc.gov/obesity/data/adult.html

[3] O’Driscoll, Megan, Gabriel Ribeiro Dos Santos, Lin Wang, Derek A. T. Cummings, Andrew S. Azman, Juliette Paireau, Arnaud Fontanet, Simon Cauchemez, and Henrik Salje. “Age-Specific Mortality and Immunity Patterns of SARS-CoV-2.” Nature 590, no. 7844 (February 2021): 140–45. https://doi.org/10.1038/s41586-020-2918-0.

[4] Levin, Andrew T., William P. Hanage, Nana Owusu-Boaitey, Kensington B. Cochran, Seamus P. Walsh, and Gideon Meyerowitz-Katz. “Assessing the Age Specificity of Infection Fatality Rates for COVID-19: Systematic Review, Meta-Analysis, and Public Policy Implications.” European Journal of Epidemiology 35, no. 12 (December 1, 2020): 1123–38. https://doi.org/10.1007/s10654-020-00698-1.

[5] Ghisolfi, Selene, Ingvild Almås, Justin C Sandefur, Tillman von Carnap, Jesse Heitner, and Tessa Bold. “Predicted COVID-19 Fatality Rates Based on Age, Sex, Comorbidities and Health System Capacity.” BMJ Global Health 5, no. 9 (September 9, 2020). https://doi.org/10.1136/bmjgh-2020-003094.

[6] https://github.com/mbevand/covid19-age-stratified-ifr#age-st...

[7] https://www3.nhk.or.jp/nhkworld/en/news/20210215_26/

> If you're disappointed by how the general population behaves here, I suspect you'd be horrified/stupefied by what's going on in the rest of the world

You definitely have a point there (and that's not to say you don't have a point in the rest of what you wrote, some very interesting stuff, before I get lost on a tangent…) as I've not left Japan during the pandemic, making a good comparison is that bit more difficult.

I certainly wouldn't deny there are many factors at play, though if I were going to bet on the major factors and their order of importance (which is hugely simplistic but lists are fun):

1. age (obviously)

2. weight

3. vitamin D levels

4. hand hygiene

5. limiting contact / social distance

I can't say that I'd be impressed at Japan's attack on (4) and (5) but (2) and (3) seem like very strong buffers for the virus and/or disease. I'll be interested to see what comes out in the wash but I'm expecting it to take years, at least, if only because of political considerations.

> BTW, your argument on flu outbreaks actually lends credence that the mask mitigations have been extremely effective.

I do wonder if it's more the case that people feeling sick are sent home or don't come to work at all? Certainly it's happening far more often than in the past (as an aside, my wife's friend had a stroke while at work, continued working, and the next morning still rang into work to excuse herself, while partly paralysed and increasingly losing motor function… and wasn't believed and told to come in!). That and all the temperature checking could improve matters from other years. Again, it needs research.

The part of me that likes dark humour would muse that bringing real sick days to Japan and the end of the hanko might justify releasing the virus from the lab it was created in…

I agree that it will take a while to get non "hot takes" but in the meantime, agree that speculation can be fun. I'd previously spent a lot of time in Japan visiting, but this past year has been my first really "living" here so it's been a bit eye-opening to see first-hand some of the extreme dichotomies of bureaucratic competence/incompetence during this period. I have a few theories of my own on Japan's low numbers:

* There's probably consistently an undercount (in my head, I just multiply the daily numbers by 5-10X), but not much more than that as we saw in Dec-Jan that a true spike will be reflected by hospital overflows (https://www.stopcovid19.jp/ has been my go-to for tracking hospitalization numbers). There's some finagling of the death toll as well (COVID-19 deaths reported as pneumonia) but I think we'll get a true accounting eventually with excess mortality modeling (offset by much lower flu) that won't be so far off to matter. [1][2] Overall, somehow, the numbers really have been pretty low. This is corroborated by most seroprevalence research. [3][4]

* There seems to have been a lot more spread amongst young people in Tokyo/Osaka, especially over the summer but it seems to be fairly well contained - I think that metabolic health does play a big role there in why there wasn't a big spike in serious cases (obesity, and maybe more importantly, hypovitaminosis D is significantly lower in Japan). As to why it didn't spread beyond that group like most other places, I believe that the lower rate of shared housing is likely a big factor - single person households makes up an amazing (and still increasing) 35% of the population. Anecdotally, there seems to have been a conscious decision by many people to not see older family members to put them at risk, and there's been some interesting (but not conclusive) research on Japanese lockdown behaviors that seem to differ a bit from what I've seen in the West. [5][6]

* While there are exceptions, again, totally anecdotally, I've seen a huge decrease in people publicly coughing, sneezing etc and when there have been people coughing in public, generally people were well, avoiding them like they had the plague. In any case, I think an early focus on ventilation and near universal masking was pretty successful in significantly lowering casual spread.

* One thing that hasn't been reported much, but Bromhexine and Ambroxol are both very common OTC cold medicines in Japan. These are TMPRSS2 inhibitors, blocking the primary entry path for the SARS-CoV-2 virus (the secondary path, endosomal entry, can be blocked by Nitazoxanide or Niclosamide). It's quite possible that in Japan, people have been unknowingly taking medicine that has been effective in moderating COVID-19 severity (this to me, seems more likely than any proposed variolation effect).[7] To me, one of the frustrating things over the past few months is that there's been enough research pointing towards many low-risk prophylactics/treatments that are probably effective for preventing severe COVID that have been pretty largely ignored.

[1] Yorifuji, Takashi, Naomi Matsumoto, and Soshi Takao. “Excess All-Cause Mortality During the COVID-19 Outbreak in Japan.” Journal of Epidemiology 31, no. 1 (January 5, 2021): 90–92. https://doi.org/10.2188/jea.JE20200492.

[2] Kurita, Junko, Tamie Sugawara, Yoshiyuki Sugishita, and Yasushi Ohkusa. “Excess Mortality Probably Due to COVID-19 in Tokyo, Japan in August and September, 2020.” MedRxiv, February 9, 2021, 2020.07.09.20143164. https://doi.org/10.1101/2020.07.09.20143164.

[3] Yoshiyama, Takashi, Yasuki Saito, Kunitsugu Masuda, Yoshiko Nakanishi, Yasutoshi Kido, Kazuhiro Uchimura, Satoshi Mitarai, et al. “Prevalence of SARS-CoV-2–Specific Antibodies, Japan, June 2020 - Volume 27, Number 2—February 2021 - Emerging Infectious Diseases Journal - CDC.” Accessed March 11, 2021. https://doi.org/10.3201/eid2702.204088.

[4] Tanaka, Akihito, Shohei Yamamoto, Kengo Miyo, Tetsuya Mizoue, Kenji Maeda, Wataru Sugiura, Hiroaki Mitsuya, Haruhito Sugiyama, and Norio Ohmagari. “Seroprevalence of Antibodies against SARS-CoV-2 in a Large National Hospital and Affiliated Facility in Tokyo, Japan.” The Journal of Infection. Accessed March 11, 2021. https://doi.org/10.1016/j.jinf.2021.01.010.

[5] CARF:Center for Advanced Research in Finance. “Japan’s Voluntary Lockdown.” https://www.carf.e.u-tokyo.ac.jp/en/research/5603/.

[6] Muto, Kaori, Isamu Yamamoto, Miwako Nagasu, Mikihito Tanaka, and Koji Wada. “Japanese Citizens’ Behavioral Changes and Preparedness against COVID-19: An Online Survey during the Early Phase of the Pandemic.” PLOS ONE 15, no. 6 (June 11, 2020): e0234292. https://doi.org/10.1371/journal.pone.0234292.

[7] Gandhi, Monica, and George W. Rutherford. “Facial Masking for Covid-19 — Potential for ‘Variolation’ as We Await a Vaccine.” New England Journal of Medicine 383, no. 18 (October 29, 2020): e101. https://doi.org/10.1056/NEJMp2026913.

Reply on news.ycombinator.com