The Bali heterogeneity?

From a Kevin Kelly email to me:

Another weird data point on the highly heterogeneous nature of this virus.

A friend of mine who lives in Bali says there have been 2 confirmed Covid-19 deaths on their island of 4.3 million residents. Yet according to him:

That makes it around 25.000 tourists from mainland China every week.

And until mid-January 2020, before the outbreak of the Corona pandemic, there were 5 direct flights from Wuhan per week.

During January 2020, 113,000 tourists from China visited Bali. During December 2019 when the Coronavirus was already spreading the number of arrivals from China was even higher because December is very busy in Bali.

So during the months of December 2019 and January 2020, approximately 220,000 tourists arrived from China alone.

Here are the official Covid-19 numbers as of 17th April 2020.

Confirmed cases: 113 | Recovered: 32 | Deaths: 2

The Crematorium in Bali’s capital city Denpasar does not see any increase in the number of cremations.

The hospitals do not have a flood of patients. There is hardly any talk on Social Media by people reporting about folks falling ill with Corona like symptoms.

The only thing I could find in Social Media groups is that business owners in Bali have reported an unusually high number of employees falling ill during November and December 2019.

Here is his Medium post
https://medium.com/@dominik.vanyi/bali-covid19-an-involuntary-experiment-in-epidemiology-immunology-a62485ce5924

Comments

We have to distingiush between the native case (without intervention) and the stochastical case (with intermittent intervention).

Another irrelevant Shark comment.

TDS confirmed.

I may as well point out a few obvious points before the comments get too eyerolly:

1. The average age in Indonesia is 28.
2. The average Balinese person doesn't spend much time in enclosed spaces.
3. High temperatures and high humidity help reduce the rate of transmission.

Throw in

Which is not surprising as the airport, through which over 95% of all visitors come in has been largely closed for foreign arrivals since the first week of February.

It's a false statement though. There were massive amounts of flights to rest of SEA until mid March. Plus some long haul flights as usual.

The airport in Bali is typical of SE Asia in that it’s open air, unwalled outside the gates.

I was there in January 2020 and noticed a busy happy atmosphere, very warm.

How much of this heterogeneity has to do with mass transport vectors? NY subway?

I strongly doubt the point about humidity. Have you not seen the recent rate in Singapore?

The number of new cases may indicate nothing about heat and humidity, but much about the living conditions of foreign workers living in dormitories.

The vast majority of the new cases are work permit holders residing in foreign worker dormitories, the Ministry of Health (MOH) said in its preliminary release of figures. Only 25 new cases were reported for nationals.

"Most of these cases have a mild illness and are being monitored in the community isolation facilities or general ward of our hospitals. None of them is in the intensive care unit," MOH said.

Singapore is definitely humid (lived there for 2 years). But Singaporeans spend 95% of their time inside in AC (residents joke about it being the airconditioned nation). Whereas the typical Balinese house has walls that slide open and a courtyard bathroom.

The recent huge spike in infection in Singapore is in foreign worker dormitories, they do not have AC

I wonder if the workers fallen ill in January were those in the tourism sector. If so, everything would be consistent with R0<1 thanks to bali's climate and general lifestyle (time spent outdoor etc.).

Also not a heck of a lot of air conditioning. I can't think of a single restaurant I went to that had aircon. The odd massage place does, as does the odd money exchange, but even really high end places like https://www.room4dessert.com are open air and have no air con.

I have seen some recent discussion on a a Japanese study on temperature and humidity on influenza. Temps over 30C and increasing humidy reduce spread.

See: https://www.maurice.nl/2020/04/09/the-proof-is-here-this-is-the-impact-of-specific-humidity/

Amazonas state in Brazil shares all these characteristics and is suffering a lot. Relatively, maybey it is the worst state in Brazil.

https://abcnews.go.com/Health/wireStory/virus-crisis-ravages-brazilian-amazon-citys-health-system-70244102
Manaus’ health care system, already strained before the coronavirus crisis, is buckling under the current onslaught of coronavirus patients. Ventilators are in critically short supply, doctors bemoan a lack of protective gear, and gravediggers increasingly have their hands full.

Amazonas state had more than 2,000 confirmed COVID-19 cases as of Sunday, the vast majority in Manaus — the only city in the state with intensive care units. The city of 2.2 million has one of the highest rates of infection in Brazil, where more than 38,600 cases have been confirmed, though experts say the total greatly under-represents the true number of infections.

Maybe everybody on Bali takes hydroxychloroquine. It is a game changer.

Forget hydroxychloroquine. Even Trump has already moved on to another fake news.

You can tell that is fake news because the WaPo writes this sort of headline -
Fox News hosts go mum on the covid-19 drug they spent weeks promoting

It is a game changer, even if the WaPo does not want anyone to know. Hannity and Carlson viewers benefited equally through Fox's prompt promoting of a drug that everyone should be free to choose.

It will be at least somewhat amusing the TDS has turned lethal.

Read that VA "study" with a sober eye. Ask yourself "is this how the abstract backgof a medical

Just take a deep breath before delving into the abstract backgof a medical

Great idea Fake News!

Everyone should be free to self-administer a prescription drug with no proven effect against COVID-19 and that needs to be precisely dosed to avoid severe side effects including blindness, organ damage and death. Oh, and amidst all the panic-buying and stockpiling of this drug, forget the needs of people who have been prescribed it for potentially fatal conditions like lupus and, oh yeah, those poor people in shithole countries who need it for people who are dying of malaria, i.e. the drug's actual indicated uses.

Someone make this guy the head of the coronavirus taskforce STAT.

if the washingtonpost.com would have objectively reported the french data about hydoxy cholorquine instead of making it about trump the
issue would have been a lotta less noisy

If Bali wants to jump start their tourism industry, they should probably test their population for antibodies to determine whether they've achieved herd immunity.

That's a good point, if indeed herd immunity has been achieved in a young age population, Bali would show it. Otherwise, it's because of the factors Lance Corporel Obvious mentioned concerning hot weather (the virus did not have a chance to spread much, and died out, due to hot weather).

Bonus trivia: Bali is a surfer's destination.

Sure would be nice to know the true prevalence... but nah... it’s more fun to just guess.

Suppose I owned a meat packing plant and could test my employees to see who is at risk and who is less so... be nice to know how I could operate my plant using recovered employees.

A big source of Balinese tourism is Australia (Sydney to Bali is about 5 hours, which for Aussies is close. Only NZ is closer.) Aussies returning from overseas are being quarantined in hotels for two weeks upon returning (worse than prison - you don't even get an hour a day in the exercise yard). Can't see Aussies rushing to Bali any time soon.

But but but ... open borders are supposed to fail?!

hi - I thought I'd lost you

Dude,

Tourists come ... drop a lot of money ... don’t do any work ... and then LEAVE.

They aren’t taking jobs the natives do.

How are all those open borders in Europe working out medically these days?

Old fat Balinese people are pretty rare.

I'm vaguely optimistic about the weather factor.

Here's something to keep an eye on: the first month of spring in huge Los Angeles County was about as cool and wet as March-April ever gets here. But finally sun and 80-90 degree weather have arrived. If summer really will save us, it's finally arrived in Los Angeles and we should be seeing it in the LA County case counts by, say, early May.

Suppose summer does save us until next fall... so you all think we will have widespread antibody testing available (and any strongish conclusions regarding whether you can get it twice) so the immunes (again supposing immunity is true) can function normally and we don’t have as severe of a contraction in The fall/winter 2020. This is like a multi-trillion dollar question.

I am cautiously optimistic but our track record so far is hot garbage.

Does the temperature/humidity actually cause lower virus transmission (like, UV rays kill the virus and high humidity makes droplets fall out of air faster) or does temperature influence human behavior to get outside more and thus, we are not all stuck indoors coughing on each other?

Even with a common cold I can't seem to understand what the true mechanism is between weather and "cold/flu season".

The mechanism doesn’t seem well understood, but with a stylised view of the facts, it surely seems that warm humid weather depresses the spread.

There are multiple mechanisms that cause droplet-based transmission to drop, particularly for respiratory illnesses, in summer.
1) The throat has a mucus membrane that is less viscous and more prone to drying out in dry conditions like cold winter air, this makes it easier for a pathogen to get through the mucus membrane and contact your cells.
2) most pathogens prefer moist surfaces and sun dries out a lot of potential fomites (surfaces where pathogens may linger and pass by contact).
3) UV radiation such as is found in natural sunlight slowly breaks down most viruses (less so or not at all for other pathogens like mold or bacteria). So the outdoors and indoor rooms with open blinds and windows are generally more hygenic than rooms and spaces closed-up and lit by lamps such as is common in winter.

None of these factors imply that Covid 19 will disappear in summer, but the crucial exponent should go down.

Also, I should have mentioned Vitamin D is crucial to immune function and direct sunlight on the skin is required for your body to produce it. People can only get it in their diets from pretty fresh meat and animal products because it breaks down more quickly than other essential nutrients. By mid-winter, if you've been indoors or heavily clothed for a couple of months and you aren't eating fresh meat or taking supplements, you're probably deficient and somewhat immune-compromised.

The wet weather in SoCal was likely protective against COVID.

One of my readers says the climatic politics is similar to the US in Australia, just flipped upside down. Northern Queensland doesn't have much of a problem and wants to open up. Southern Victoria is reluctant.

Are there similar examples by climate in other large countries? Perhaps Italy.

I think Victoria, the second hardest hit state, wants South Australia, the least infected state, to loosen restrictions so they can see what happens.

This is not completely unreasonable. No one really needs South Australia and it's easy enough to rope it off from the rest of the country.

I sure as hell want the southern US states to "let 'er rip" so I can watch safely from my home in CO to see what fresh hell will/won't unfold.

Though Colorado's shelter-in-place order is up on Sunday and some businesses will re-open Monday, so we're not entirely innocent either. But still no restaurants, and open businesses still have to follow mask and group (<10) protocols.

Brazil is showing that is not true. The state of Amazonas is one of the most severely hit state im Brazil.

Lets try another rationale.

Thats probably to do with having only one city with any ICUs in the entire state as much as it is to do with anything else.

Idk if weather has a tempering impact or not. But I wouldn't conclude that because there are deaths in hot weather places that means the weather has no or little impact

I’m in Brazil. There are enormous perverse incentives to fake cases. Our nurse friend in CE is shocked that they are coding clear Asthma, no cv19 deaths as Covid.

Not that I particularly believe the weather is the factor, but the numbers here are not a reliable data point. At all.

It seems that lesser developed nations took this disease more seriously, and earlier.

Talk loud and die

Breath soft and live

https://quillette.com/2020/04/23/covid-19-superspreader-events-in-28-countries-critical-patterns-and-lessons/

I have suspected the American fondness for talking has contributed to their demise:

https://www.youtube.com/watch?v=yR5Z4n1TdSI

FYI, your posts may create the impression that you’re taking some pleasure in Australia’s success with the virus relative to the US (i.e., it seems like you’re feeling good about dead Americans). Maybe tone it down a little bit, unless that’s your intent.

I don't think I'm reducing the chances of an improved public health response in the US, which is what I would like to see.

US media gives us the impression that besides a few glittering, neon business districts, China is a grim, unhappy tyranny with millions of virtual slaves making gym shoes and computer parts in sweatshops with nets around the roof to keep the suicide levels in check. Yet according to this story affluent Chinese are jetting around to the premier tourist spots in Asia, as they once did to North American destinations. They send their offspring to pricey American colleges that most Yankees can't afford. What gives? Are these the most oppressed proles in history or are we being fed some kind of propaganda?

China is both large enough and prosperous enough to have a repressed underclass and a jetsetting Ivy League educated elite.

Yes, China is like if Europe and Africa were one country—a decently large decently prosperous population that still needs to lift a much larger objectively poor population out of the poverty that has been their lot for hundreds of years.

Bali isn't a "premier" spot if you define that by price. It has been the favored spot of Australians with more time than money for decades. You don't need to be affluent or "elite" in China to afford to travel to cheap Southeast Asian destinations. Middle class will do.

So maybe China isn't exactly the hell on earth that's described to the west, unless you're Uighur or a Tibetan. Of course the US hasn't been particularly kind to the native Americans but then that's so far in the past it hardly bears mentioning. After all they were given citizenship in 1924. The Dakota and their Cheyenne buddies are famous for taking up all the hotel rooms at the Cannes festival and roaring around the Missouri River reservoirs in their Cigarette speedboats.

The top earning 10% of china is a lot of people.

I appreciate Cowen's posts on this topic (heterogeneity and the novel coronavirus) because there's so little we know about the novel coronavirus, but like every topic covered at this blog, the image of Jesus always appears in many readers' mashed potatoes. This blog post about Bali doesn't quite fit the anti-immigration argument that has been the soup du jour of late. Not only did Bali have a steady stream of visitors, many came from coronavirus central (Wuhan). Of course, Trump provides a steady stream of disconnected data points to support whatever he and his comrades are selling on any given day. Back when Trump was selling the re-opening of the economy on Easter Sunday, I could see the image of Jesus in my mashed potatoes.

Your posts are always intriguing. Little to no facts, heavy on the hate for Trump.

I'd be interested to know where your source for information is?

He told you... his mashed potatoes. Sadly, it seems like that’s almost as good a source as any... although the MR coverage has been great.

More evidence that Trump banned the wrong country first. Had he stopped flights from Spain and Italy, the US would be in better shape. Instead he opted for China and that politically motivated decision cost America a lot of lives and a large chunk of economy.

Spread from China came first, so it was the right choice when he did (less spread from China anyone?). Italy sooner would have been better, but that wasn't as obvious to anyone.

The entire EU. And the fact that the UK and Ireland, along with other countries not in the Schengen zone were exempted, it is obvious that an idiot was in charge of trying to keep coronavirus continuing to be spread from one continent to another.

The entire EU travel ban was basically a fiasco. Accepting that fact makes it much easier to talk about travel bans in the abstract. Trump's travel bans were, to be extremely charitable to the point of damning with faint praise, ineffective.

Seems like a religious beliefs. You say it with such certainty.

Do you have access to that timeline where a million more people fly direct from China to the USA in February?

And in that timeline, does the USA have FEWER Cv19 cases? How or why does the USA in your alternative timeline LARP have fewer cases?

Preach it. Spread the Gospel. Tell us why 1M more travelers from China, and to China and back, creates FEWER cases.

Because I can think of a million reasons you could be wrong, but the only reason I can think that you are right is that you want it to be so.

'does the USA have FEWER Cv19 cases'

At what point of time? Absent a vaccine, it is reasonable to assume that humanity in total will end up with roughly the same infection rate over the next couple of years.

There is no question that a state like Hawaii in theory can ban all travel and remain effectively free from spread. In practice, the federal government continues to be in a position to overrule that ban by transferring federal employees as it wishes - mainly military, but others as the federal government feels necessary.

There is no time line where the virus does not spread throughout human populations, but somehow, this inescapable fact leads to a number of people not wanting it to be so.

Yes, we can look at our northern neighbor Canada for an alternative history where we never banned travel from China. Canada never banned travel from China specifically, and only banned travel from all countries in March. Yet Canada has a much more controlled outbreak than the US.

There are a number of reasons why the travel ban could have resulted in more cases in the US. People could have felt more complacent because the government was telling them the virus was only in China (which explains things like testing failures). Or the theory that the original strain in China is less deadly than the later strain that mutated in Europe could be correct, meaning that if you are going to go for herd immunity, better to get herd immunity from the Chinese strain. Regular air travel from China would also mean more air freight capacity for important equipment such as masks. And travel bans reduce trust in the authorities and reduce people’s willingness to cooperate in things like voluntarily reporting symptoms and contact tracing.

In any event, the data suggests quite strongly that countries that banned travel from China early have done no better than nearby countries that didn’t. And you don’t just have to look at the US/Canada. You see this same dynamic in other parts of the world—in Europe, Italy was the first country to ban travel from China and was also hit the hardest. In Asia, Hong Kong did not ban travel from China early on while Singapore did, and now Singapore has 10x the cases of Hong Kong.

So i don't know if you know this . . . but Canada is not America.

Canada is not the timeline of America with 1 million more Chinese Travelers in February than it had.You pretend it is. Maybe your Vox Friends believe it is.

But I doubt you do.

Are you paid by China to pretend Canada is the USA?

There's a lot of political motivation for Trump opponents to rewrite history, that's for sure.

Trump opponents need only quote his tweets, briefings, and press appearances, thus requiring Trump supporters to do their best to ignore history, as trying to rewrite it is laughably mission impossible.

Ha! I figured "Northeasterner" was the troll!

One of the funniest things here has been watching your dedication troll hunting, which certainly must be amusing to a number of commentors.

Keep up the good work, every comment section needs it dedicated anti-trolls too, who can be counted on to just add to the time wasting.

The nov-dec outbreak is interesting, as I think it’s possibly my fam for this is Jan-feb and this community spread in my area began in dec-jan.

What’s really annoying is that it’s technically possible to answer thee questions with antibody testing.

But we don’t have enough because we didn’t take this seriously until March. It is amazing that we haven’t really begun to estimate prevalence.

The economy is being ruined, we have a work force to do this, we know the recipe for tests..: and yet it’s almost freakin May.

What’s is the damn deal!?!??

I’m hearing so many anecdotes from different countries about how it already spread there in Nov-Dec but no hard evidence. It would be a total gamechanger if that were true, but I’d expect someone somewhere in the world to have come up with stronger evidence that people’s recollections if it were.

China has a very strong incentive to look into these rumors and prove this virus was spreading elsewhere in the world earlier as that means there would be a chance it didn't originate in China at all, yet I don’t think they’ve come up with any solid corroborating evidence.

I agree, one would think someone would have noticed. But... my family has an anecdote for sure. Soon after the travelers came back from Chinese New Year, we all got sick back to back with a respiratory illness that causes fever, dry cough (in my case to the point of hacking up blood), loss of taste, head and body aches and negative tests for influenza, strep etc.

Now those symptoms so common across the set of possible illnesses, and there were no reports of people dying out of proportion to normal... so who knows.

Sure would love accurate widely available antibody tests tho.

https://www.google.com/amp/s/www.nytimes.com/2020/04/23/us/coronavirus-early-outbreaks-cities.amp.html

The nytimes had an article a few days ago comparing official covid-19 deaths to excess deaths in past month compared to deaths a year ago as a proxy for unreported covid-19 deaths. NYC excess deaths were about 30% higher than reported covid-19 deaths; most oecd countries were 50-100% higher. Indonesia had 84 reported covid-19 deaths and c. 1000 excess deaths or over 1000% higher so that's probably some of it. However, even with that many unreported covid-19 deaths, Indonesia still has a surprisingly small outbreak.

What does the "scientific method" mean? Here's a reminder: https://www.washingtonpost.com/outlook/2020/04/23/scientific-method-cant-save-us-coronavirus/

It is shocking (and embarrassing) that we are approaching the end of April and we still don't know some pretty basic things. The most basic is that we don't know have a good estimate of how many of us have had Covid-19 and where we live. Even with the (also) shocking inability to test widely, we clearly have had enough tests available to do random testing of the whole population. Why hasn't this happened?

The evidence from Bali is just one more example that points to what I'll call the "mechanical" aspects of the coronavirus. Apparently there is a debate as to whether or not viruses are even living things. Just as clearly they are affected by heat, cold, humidity, soap, and even time. There is also a real difference between ingesting say a thousand coronaviruses and say a million coronaviruses. This is all easy stuff to figure out. So why don't we know more about it?

At the risk of revealing myself as a paid up member of Cowan's Army (modeled after Dumbledore's Army), it is clear that the two lesson's of this pandemic are: (1) Governments really matter, and (2) Government's have completely failed us. (And 2.1 Trump/Trudeau and their ilk don't really matter.)

"Even with the (also) shocking inability to test widely, we clearly have had enough tests available to do random testing of the whole population. Why hasn't this happened?"

I think anyone who hasn't had to go through the process (myself included) of being tested for COVID-19 has to do it first before being so glib about "well just test everybody, OK?"

There are going to be huge lines, waits, exhausted people collecting samples, testing samples. It's not like the mailman walks to your front door, has you spit in a cup, and you go about your day. It's pretty labor intensive from start (patient) to finish (lab emailing test results).

I agree with commenters above that we are still pretty ignorant about how covid-19 is transmitted, especially how it is transmitted by travelers. Not just Bali but a number of Southeast Asian destinations receive heavy traffic from China. Thailand also receives a lot of Chinese visitors, had cases relatively early on and was very late when it came to imposing social distancing measures and they still only have 50 deaths and fewer than 3,000 cases.

Warm climate may help limit transmission but Singapore and Miami-Dade county in Florida have had lots of cases so it must be one mitigating factor among many. Business travelers and skiers seem to be at risk but Thai and Balinese locals don't seem to have many cases traced to infection from visiting Chinese between November and January.

Thailand is pretty good with mask use, at least better than most of Europe and the Americas have been. (Thailand in March and April is still warmer and more humid than Miami-Dade, for that matter. I can also believe that particularly cold temperatures help too, that there's an optimal climate for the virus. I also don't rule out the mutations leading to multiple strains theory either.)

I agree that there's a number of factors; there are a lot of individual mitigation strategies that bring down the exponential to a lower number. Once you do enough to bring it from exponential growth to exponential decay, you're pretty good. Countries can't do too much about the weather (whether heat or humidity), so you control what you can, but some places may need greater restraints than those that are naturally blessed.

It’s not just Bali, many other Southeast Asian countries that get huge numbers of Chinese tourists and didn’t close their borders early are barely affected by this, such as Thailand and Cambodia (remember also that Thailand had the very first known case outside China—in a tourist—in mid-January and didn’t close its border until late March when it closed its border with everyone—yet no viral explosion there).

I’m becoming increasingly convinced that tourists are low-risk. Tourists often don’t take public transportation, don’t spend a lot of time mixing in enclosed indoor spaces with natives, and certainly don’t visit typical hotspots like migrant worker dorms, prisons, or nursing homes. This virus is mostly spread within families and in enclosed indoor environments; you’re not likely to get it just by being near someone who has it on a beach for a few minutes (even Florida is doing better than people predicted after opening its beaches). This virus was probably spread mostly by returning citizens in each country who then went on to spend sustained indoor time with their families and other contacts.

Many third-world countries might be doing well because they simply don’t have a lot of outbound tourists or migrants returning home and the inbound tourists they get are low-risk.

Are there seasonal tourist patterns from various areas within China?

For example, Quebec in Canada has an early mid winter break, 10 days I believe where huge numbers head to Florida. The timing of which was inopportune this year.

I strongly suspected a family link on MR but was shot down by the pro-family ideologues. To be clear I didn't say families caused transmissions that's a strawman. I said extended indoor time together where there's active talking and sharing of the air would likely do the trick. So family gatherings, restaurants, choir practice, cruise ships, and church service. If the indoor theory is true then we can loosen up a lot of the restrictions and reopen commercial outdoor activities.

Yes, 78-85% of the clusters in China were within families: https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf.

Close contact indoors is the riskiest thing. Being generally around an infected person for a short period of time does not seek that risky, particularly if in a well-ventilated outdoor environment.

" If the indoor theory is true then we can loosen up a lot of the restrictions and reopen commercial outdoor activities."

On the other hand, if it's true than we need to separate family members as soon as one of their contacts have a suspected case, but them in hotel rooms or centralized quarantine. That's more restrictions in one way, fewer in another.

For some reason, people want there to be fewer random outcomes.

Maybe it's a natural reason, that we prefer a predictable world.

People's livelihoods are being ruined. They want to think that the personal and public policy decisions causing this destruction are based on some reasonably quantifiable assessment of cost and benefit, and not just flailing untethered to solid information.

Fog of war.

And not just "livelihoods."

Yeah, but this particular psychological need is what’s causing people to support policies that have no solid evidence-based support. Heck, Trump’s latest immigration ban barely even pretended to be about COVID, yet most people seem perfectly happy to accept it as an anti-COVID measure.

I think people ought to embrace the randomness. Perhaps we would’ve done better if public policy had been driven by a “first do-no-harm” approach all along, deploying non-disruptive measures such as masks and testing first and only using disruptive measures like lockdowns and travel bans only once there is strong evidence supporting the efficacy of those measures.

Based on what we know about transmission along networks, it is easy to visualize the mechanism by which some places would end up lucky and some places would end up unlucky.

And we can see how the smaller the place, the less likely it is to median.

Immunity from a previous infection cycle?

Look at India. For the population the numbers are tiny. Again, previous immunity?

Hypothesis. Places with large numbers of travel from across China had exposure early to less virulent and dangerous strains of this virus. The difference in spread and fatality rates in places like Korea and Japan, even west coast US and Canada.

If there was a vaccine to be had, wouldn't that be a place to start looking?

China had SARS-CoV-1 the prequel to today's SARS-CoV-2. If anybody got herd immunity it should have been them. But that very clearly didn't happen. So I count that as a point against herd immunity.

News Alert.

Bali is part of Indonesia.

Indonesia is experiencing the greatest increase of covid in SE Asia: https://www.npr.org/sections/coronavirus-live-updates/2020/04/17/836783432/indonesia-now-has-the-most-confirmed-covid-19-cases-in-southeast-asia

Indonesia now has the highest number of confirmed COVID-19 cases in all of Southeast Asia, according to numbers released by the government on Friday.

"The Health Ministry in Jakarta reports 5,923 positive cases — following the country's largest daily jump of more than 400 new infections since Thursday. COVID-19 has killed 520 people in Indonesia. In the region, only China, where the novel coronavirus originated, has a higher death toll.

"Transmission is still occurring. This has become a national disaster," Health Ministry official Achmad Yurianto said on Friday, Reuters reports.

He also said testing has increased up to threefold in two weeks."

Right. Indonesia is an aggregation of a very large population. Individual islands will fare better or worse within that larger data set.

But why does Bali appear to be an island apart? In America, cases appear to concentrate in nursing homes, health care workers, and prisons. The most serious cases are in people with high blood pressure, obesity, and/or diabetes. Perhaps Bali's population is less likely to fall ill to a more serious form of COVID because of age and lifestyle. Perhaps their cases are asymptomatic. Or perhaps they find it easier to maintain separation when all the tourists leave. Or perhaps it is just easier to shut down an island from outsiders before the disease gets a foothold. Without data what can you say?

"In America....[t]he most serious cases are in people with high blood pressure, obesity, and/or diabetes."

So...the most serious cases in America are...typical Americans?

Joking aside, how do we know those are actually making it worse, or if you're just picking up the population attributes in general?

Data out of a New York hospital listed the deadly trifecta as the most frequent comorbidity of hospitalized patients. So if you have covid and you are in a hospital bed, assuming they give those to the sickest, that is the link. The next assumption is that Bali may not have a large percentage of the population that requires hospitalization, because they tend to be younger and healthier, so health care workers do not become a big hot spot. Don't know about prisons or nursing homes in Bali. So if you have a healthy population that gets a milder version, and you don't have the institutional hot spots, caseload and outcomes might be lower.

The article I read this morning (sorry was on my phone so don't have link now) said that roughly 1/3 of hospitalized patients had diabetes. Well, about 27% of Americans over 65 have diabetes (I'm cheating a little bit because the rate is lower for under 65 but they make up most hospitalizations). I just want someone to come out and say whether that delta is statistically significant or not.

You make a valid point. It sounds awful but that is a pretty representative sample of Americans over 65. But my point that the Bali residents might be healthier and then might be less prone to a severe form of the disease, less likely to cause additional cases at hospitals, (and assuming that viral load might make worse outcomes there), etc. Or the data sucks and this is just another exercise in mental masturbation.

Balinese are an island apart, literally. They eat modestly, with little sugar, are rarely overweight, and smoke far less than the neighboring Javanese, for example.

Here is Florida we are wondering why the Orlando area were Disney world is, is not a huge hot spot. Random, it just happened that none of the tourist carried covid19?

Right place at the right time. Sometimes luck is all you need. Spring Breakers didn't seem to cause a big outbreak. Mardi Gras did.

This is another datapoint on the idea that spreading happens inside and not outside. Bali is an outside holiday destination. This also is consistent with Australia having low spread during its summer.

The data point about inside spread was from China. They had infected people quarantined at home with family during a lockdown. Given generally tight quarters it rapidly spread to other family members. Thus the data says that Covid spreads indoors. Close proximity to an infected person is the issue is the key. Nursing homes, hospitals, prisons, meat packers, share two things, indoors and close proximity with infected individuals. You can be at an outdoor sporting event and I'm sure you can spread the virus if the fans are in close proximity.

It is an archipelago and it is relatively easy to control movement between islands. Bali is interesting because it is very popular with foreign tourists -- including Chinese -- and is also only semi-urban at best in a few places. Its example as well as those of other Southeast Asian tourism hotspots show that you need something other than a number of infected individuals passing through your territory to get an epidemic started.

Maybe Chinese tourists tend to not party with the locals. Or perhaps the combination of heat, humidity, and mostly outdoor activities and the lack of genuine urban density (at least by Asian or Manhattan standards) makes it low-risk.

Bangkok, Manila and Jakarta seem to each account for around half of all of the cases in their respective countries but none of these cities has yet experienced a New York-style meltdown. Seoul, Taipei and Hong Kong are in remarkable shape.

There were 571 cases in China before the Wuhan lockdown on Jan 23, Because most of the early cases were related to the seafood market and these people have modest means, it's possible that not a single case traveled to Bali. The rest of China was much less infected. Around that time there was 1 case detected in Thailand ( Jan 13). Taiwan detected its first case on Jan 21. There were no flights out of Wuhan after Jan 23.
There is a small epidemic of Dengue fever currently in Bali. The two diseases ( Dengue and Covid-19) can be difficult to distinguish because they share clinical and laboratory features.
It's possible there are Covid-19 covert cases in South East Asia attributed to Dengue disease.

https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30158-4/fulltext

I haven't searched at all yet, but I wonder if some of these southeast Asian places have previous exposure to some corinaviruses due to living in contact with bats.

FWIW,
https://www.theluxurysignature.com/2015/02/13/basic-balinese-etiquette-to-keep-in-mind-when-visiting-bali/

"Greet Strangers with a Handshake, or also known as the Salam – when meeting people for the first time, offer them a handshake and a slight nod of your head. When a man is introduced to a woman, wait for her to offer her hand first. If she doesn’t, then don’t give out a handshake.

When offering handshakes to older people or those in authority, slightly bend the body facing the person."

Possibly less handshaking going on. Though I suspect humidity is more of a factor. Current temperature 80F, 94% humidity.

Google says that life expectancy in Bali is 64.6 years for rural and 61.1 years for urban dwellers. How about his: there just are not that many people in Covid-19 high risk groups (old age, immunocompromised) in Bali because they have already died of other causes.

Natural followups:

1. Cross reference the passenger manifests on all those direct from Wuhan flights with Covid cases/deaths in China after. Maybe the Chinese people who like to hit Bali for vacation are simply not the type that shop at wet markets or associate with people that do?

2. What do Chinese people do in Bali? Do they hang with each other, avoid staff and natives except, say, when ordering at outdoor cafes?

3. Of course an antibody test would be helpful. So would a mass antibody test in Wuhan. After the dust settled (and before we have another flare up in China), it would be good to know what % of the population in Wuhan was exposed to the virus. In NYC a recent test says maybe 20%. If the Wuhan number is close to that then it may simply be that very few spreaders went to Bali and those that did gave it to fellow travelers who just brought it back to Wuhan.

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