COVID-19 Coronavirus Containment Efforts

[morrobay]

June 11, 2020 - The D614G mutation in the SARS-CoV-2 spike protein reduces S1 shedding and increases infectivity
https://www.scripps.edu/news-and-ev...611-choe-farzan-sars-cov-2-spike-protein.html

Yes increased infectivity but are there any data/studies showing whether the D614G mutation is more or less lethal?

 

[atyy]

Yes increased infectivity but are there any data/studies showing whether the D614G mutation is more or less lethal?

The infectivity refers to cell culture data, and may not apply to transmissibility (though it is consistent with the variant becoming more common). One of the papers looking at the variants was not able to find any difference in severity between them: https://www.cell.com/cell/pdf/S0092-8674(20)30820-5.pdf

 

[bhobba]

For the flu vaccine, there seems to be debate about making it mandatory for various groups of people.

No debate for me. I do not know if being on the cocktail of drugs I am on it is a requirement I have it, but when I see my doctor it's where do you want it.

Thanks
Bill

 

[vela]

California's locking down again.

https://www.latimes.com/california/...ifornia-county-rollback-reopening-coronavirus

 

[Buzz Bloom]

I found some interesting stuff on the Internet (which I have cited below) regarding dogs trained to detect covid-19.

https://www.bbc.com/news/uk-england-beds-bucks-herts-53254200​

https://news.sky.com/story/covid-do...o-250-people-an-hour-for-coronavirus-11989180​

https://podcasts.apple.com/gb/podca...t-us-out-lockdown/id951048357?i=1000472322269​

https://canvethospital.com/news/disease-detecting-dogs-even-covid-19​

I have not been able to find any peer review articles about the details of the training. I hope someone can help me find some.

I also have an mp4 file which I think may be from facebook. I have not included it in this post because I am not sure about the relevant PFs' rules.

 

[bob012345]

Has the definition of what constitutes a new case recently changed? Are they including 'probable' cases as new cases now? Are they also including people who test positive for antibodies but never were tested for the virus as 'new' cases too?

 

[Astronuc]

Has the definition of what constitutes a new case recently changed? Are they including 'probable' cases as new cases now? Are they also including people who test positive for antibodies but never were tested for the virus as 'new' cases too?

That's hard to say, and it probably depends on who is doing the reporting. I believe 'probable' cases are treated separately, but it's not clear how uniform and consistent the reporting is across 50 states and the 3000+ counties.

See different ways of reporting
Alabama - https://alpublichealth.maps.arcgis..../index.html#/6d2771faa9da4a2786a509d82c8cf0f7
Arizona - https://www.azdhs.gov/preparedness/...se-epidemiology/covid-19/dashboards/index.php
California - https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Immunization/ncov2019.aspx#
Florida - https://experience.arcgis.com/experience/96dd742462124fa0b38ddedb9b25e429
New York - https://covid19tracker.health.ny.gov/views/NYS-COVID19-Tracker/NYSDOHCOVID-19Tracker-Map
Texas - https://txdshs.maps.arcgis.com/apps/opsdashboard/index.html#/0d8bdf9be927459d9cb11b9eaef6101f
Washington - https://www.doh.wa.gov/Emergencies/NovelCoronavirusOutbreak2020COVID19/DataDashboard

Compare to https://ncov2019.live/data/unitedstates and https://covidtracking.com/data
ncov2019.live has greater numbers than reported by the states, so I believe they may count some 'probable' positive cases and deaths in their numbers. However, the discrepancies are not clear to me.

Meanwhile, CNN reports that Governor Kevin Stitt of Oklahoma has tested positive for COVID-19
https://www.cnn.com/2020/07/15/politics/kevin-stitt-oklahoma-governor-coronavirus/index.html

The health department reports that it is not clear how he was exposed. "Dr. Lance Frye, the commissioner of the Oklahoma State Department of Health, said they don't know exactly when Stitt was infected, but that it would've been within the last couple of weeks."

Update: NY Times reported on how states report deaths - probable and confirmed
https://www.nytimes.com/interactive/2020/06/19/us/us-coronavirus-covid-death-toll.html

 

[Jarvis323]

Incomplete classification, but still an interesting observation.

https://www.google.com/amp/s/hbr.or...pandemic-reshape-notions-of-female-leadership

 

[StevieTNZ]

I like New Zealand's response. Real competent leadership.

 

[PeroK]

Incomplete classification, but still an interesting observation. View attachment 266419

One of the things a lot of journalists have struggled with re the COVID-19 pandemic is the concept that different countries have different populations and the total numbers are not comparable. Only numbers adjusted for population are comparable. And also that countries are geographically very different.

If, for example, you compare Iceland with the less populated and more remote US states, there's a general correlation:

				Per	Million
	Pop	Cases	Deaths	Cases	Deaths
Iceland	340,000​	1,900​	10​	5,600​	29​
Wyoming	580,000​	2,000​	22​	3,400​	38​
Alaska	730,000​	1,600​	17​	2,200​	23​
Hawaii	1,400,000​	1,300​	22​	900​	16​

Therefore, if we compare Iceland with comparable US states, then the picture is very different.

 

[Jarvis323]

One of the things a lot of journalists have struggled with re the COVID-19 pandemic is the concept that different countries have different populations and the total numbers are not comparable. Only numbers adjusted for population are comparable. And also that countries are geographically very different.

If, for example, you compare Iceland with the less populated and more remote US states, there's a general correlation:

				Per	Million
	Pop	Cases	Deaths	Cases	Deaths
Iceland	340,000​	1,900​	10​	5,600​	29​
Wyoming	580,000​	2,000​	22​	3,400​	38​
Alaska	730,000​	1,600​	17​	2,200​	23​
Hawaii	1,400,000​	1,300​	22​	900​	16​

Therefore, if we compare Iceland with comparable US states, then the picture is very different.

That's true; but it's worth considering that Iceland has done more than twice as much testing per capita as the US.

 

[PeroK]

That's true; it's still not clear though because we can't fairly compare the numbers directly. Iceland has done more than twice as much testing per capita than the US. Who knows how much testing Alaska has done, or how accurate the death counts are. And then there is chance. With deaths in the 10-20 range, chance can be a pretty big factor. And what strain showed up, when is an important factor.

Comparing an island country of 300,000 with a country of 300,000,000 is fundamentally problematic. You want to say that Iceland vs the USA is a logical and valid comparison; but Iceland vs Alaska is not?

 

[Jarvis323]

Comparing an island country of 300,000 with a country of 300,000,000 is fundamentally problematic. You want to say that Iceland vs the USA is a logical and valid comparison; but Iceland vs Alaska is not?

I'm just pointing out that even your adjustment doesn't cut it. Just an estimate, after looking here and some other places, (https://www.politico.com/interactives/2020/coronavirus-testing-by-state-chart-of-new-cases/), I would say that Alaska, Hawaii, and Wyoming have likely undercounted compared with Iceland by about a factor of 4 or more.

But the numbers are low enough to just observe Iceland did good. You can compare one state to Iceland, but the leader of the US is in charge of the whole country. So that comparison is not a comparison of national leadership.

You can't be asking for too much more performance from Iceland, but there is a lot more to ask of the US. Of course there are differences due to population density and so forth. So, maybe you can say the US leadership has a different problem (maybe a harder one), but you can't say they did a good job.

So one leader had a better outcome than the other, but one may have had an advantage. The next thing to do is compare actions. I think the articles in the topic are looking at that as well, and it's those comparisons which really highlight leadership quality differences in my opinion.

 

[PeroK]

I'm just pointing out that even your adjustment doesn't cut it.

I wasn't trying to make a definitive case. I simply highlighted the absurdity of the data analysis I was presented with.

 

[Jarvis323]

I wasn't trying to make a definitive case. I simply highlighted the absurdity of the data analysis I was presented with.

What are you talking about, the testing rate I mentioned? It seams Iceland has tested a much larger percentage of it's population, which you didn't account for. That's all the data analysis I did.

 

[mfb]

Confirmed cases in the US exceeded 1% of its population.

Excluding micronations/territories with a small population: Qatar has 3.5%, Bahrain about 2%, Chile and Kuwait about 1.5%, Oman, Armenia, Panama, Peru and the US a bit more than 1%. Brazil has a bit less than 1% at the moment.

 

[PeroK]

Confirmed cases in the US exceeded 1% of its population.

Excluding micronations/territories with a small population: Qatar has 3.5%, Bahrain about 2%, Chile and Kuwait about 1.5%, Oman, Armenia, Panama, Peru and the US a bit more than 1%. Brazil has a bit less than 1% at the moment.

One noticeable thing is that the Middle East countries with a large number of cases - Qatar, Bahrain, Kuwait, Oman and Saudi Arabia - have a very low death rate. Not just a low CFR, but a low death rate per population generally. For example:

Saudi Arabia and Italy both have about 243,000 cases now: Italy has had 35,000 deaths, but SA only 2,370.

Canada and Qatar have 109,000 and 105,000 cases respectively, but 8,800 against 150 deaths.

Belgium and Oman have about 63,000 cases each, but 9,800 against 290 deaths.

(As an aside, the global death rate generally is about 60 people per 100,000 per month. If you picked 100,000 of the world's population at random, then about 60 would die in the next month. In other words, 150 deaths from 100,000 people is about the expected death rate given the time COVID-19 has been around.)

 

[morrobay]

With 13% world pop obese. (U.S. 40%) 9% diabetes. 27% hypertension.Thats about 1/2 co morbidities for world population.

 

[bhobba]

With 13% world pop obese. (U.S. 40%) 9% diabetes. 27% hypertension.Thats about 1/2 co morbidities for world population.

It's worse than 9% for diabeties in the sense that even pre-diabeties is a significant risk factor. It is estimated 1 in 3 people have diabeties or pre-diabeties. I think there is well over 50% of the population with at least one co-morbidity. Over 65 I think a person without a co-morbidity is very much the exception rather than the rule. I do not know if the reason the elderly have a higher death rate is their age or co-morbidities.

Thanks
Bill

 

[Ygggdrasil]

The Oxford team developing a adenoviral-based vaccine is planning to test their vaccine by intentionally exposing vaccinated volunteers to the virus:

The team behind the Oxford Covid-19 vaccine hope to begin tests on volunteers who will be intentionally exposed to the virus in a “challenge trial”, a move seen as controversial since there is no proven cure for the illness.

Although challenge trials, in which healthy volunteers are given a pathogen, are routine in vaccine development, taking the approach for Covid-19, where there is no failsafe treatment if a volunteer becomes severely ill, has been questioned.

In human challenge trials volunteers are intentionally exposed in a controlled laboratory setting, meaning the trial can be completed in weeks and requires far fewer people.

https://www.theguardian.com/science...lunteers-lab-controlled-human-challenge-trial

While these challenge trials would quickly be able to give an idea of the efficacy of the vaccine (how well does it protect against infection by the coronavirus), the trial would not provide sufficient data on safety. The safety data would have to come from ongoing phase III trials from the group (which will also provide more data on efficacy in real world situations). According to the Guardian article above, the phase III trials have "recruited 10,000 trial participants in the UK, about 5,000 in Brazil and 2,000 in South Africa, with a second trial in the US aiming to recruit as many as 30,000 participants."

 

[bhobba]

The Oxford team developing a adenoviral-based vaccine is planning to test their vaccine by intentionally exposing vaccinated volunteers to the virus:

I expected that. The Oxford group is very gung ho - I have even heard some refer to them as 'crazy'. It certainly will speed up getting the vaccine out there, but even with volunteers I have concerns about its 'morality'.

This is partly related to the view of some working on vaccines that the Oxford vaccine approach has some inherent problems:
https://www.hospitalhealth.com.au/c...id-19-says-professor-1538816326#axzz6STOe3pbD

At a minimum I would want any volunteer to be aware of the above issues.

I like the suggestion of Professor Petrovsky that, once proven safe, as part of phase 2 trials, using the vaccine to attempt to break up second wave outbreaks. He is preparing plans to do that with his vaccine if the Victoria outbreak gets out of hand and threatens a second wave across all of Australia.

Thanks
Bill

 

[mfb]

Several US states register over 0.1% of their population as new cases every week. With 30,000 participants that's over 30 new cases per week if the vaccine does nothing, even if you don't add dedicated tests. Give half of them a placebo, skip the first two weeks, three weeks later you expect 50-100 new cases in the control group and can compare this with the group that got a vaccine. This number might go down in the future if the states get the outbreak under control, of course.

Testing everyone in both groups twice in that time span will increase the statistics a lot (and will give another data point on how many cases the US is missing).

 

[Jarvis323]

There is some seemingly good news about immunity.

SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls

Memory T cells induced by previous pathogens can shape the susceptibility to, and clinical severity of, subsequent infections1. Little is known about the presence of pre-existing memory T cells in humans with the potential to recognize SARS-CoV-2. Here, we first studied T cell responses to structural (nucleocapsid protein, NP) and non-structural (NSP-7 and NSP13 of ORF1) regions of SARS-CoV-2 in COVID-19 convalescents (n=36). In all of them we demonstrated the presence of CD4 and CD8 T cells recognizing multiple regions of the NP protein. We then showed that SARS-recovered patients (n=23) still possesses long-lasting memory T cells reactive to SARS-NP 17 years after the 2003 outbreak, which displayed robust cross-reactivity to SARS-CoV-2 NP.

https://www.nature.com/articles/s41586-020-2550-z

T-cell immunity tests could be more reliable than antibody tests in measuring the spread of coronavirus in the community, according to a new study.

Scientists have found that some patients who had experienced mild symptoms of Covid-19 did not appear to have developed antibodies. However they did show “strong, specific T-cell immunity”, according to the authors of a report in Science Immunology.

“If, as appears the case, measuring T-cell immunity is a more enduring and reliable marker of adaptive immunity in Covid-19 than antibody, it will be valuable to achieve roll-out for health services of commercial T-cell testing kits,” said Rosemary Boyton and Daniel Altmann, professors of immunology at Imperial College London.

https://www.independent.co.uk/news/...-test-t-cell-antibody-community-a9625811.html

Since it has been observed that anti-bodies to sars-ncov-2 can fade quickly, this seems like good news for long term immunity; we may not need anti-bodies. I'm not sure though what it really means, and how it affects vaccines, but it is being suggested it is an important factor.

Moderna’s Phase 1 study also indicated that its vaccine candidate can offer a double defense against the virus. The Telegraph explains that it may be essential for vaccines to provide this type of advanced protection to increase COVID-19 immunity. Not all vaccine candidates will also produce T cells, the report notes. Apparently, at least one major vaccine candidate in China does not lead to T cell production, although The Telegraph doesn’t name the drug.

https://bgr.com/2020/07/15/coronavirus-cure-moderna-vaccine-phase-3-news/

 

[Astronuc]

Stretches of South Texas, especially the Rio Grande Valley and the Coastal Bend, have seen Coronavirus infections spread so quickly in recent weeks as to push local hospitals to their limit. The four-county region that includes Harlingen has just 21 ICU beds still available for a population of about 1.4 million people, according to the latest state data, and ambulance operators have described wait times of up to 10 hours to deliver patients to packed emergency rooms.

https://www.texastribune.org/2020/07/18/texas-coronavirus-hot-spots/

Last Friday, Nueces County Medical Examiner Adel Shaker was shocked to learn that a baby boy, less than 6 months old, had tested positive for COVID-19 and died shortly after.

No mention of a pre-existing condition or co-morbidity.

Two weeks ago, there were just seven positive COVID-19 patients in the Amarillo hospital; by this week, that had more than tripled to 24. Earlier this week, a patient in their 30s died; now, the family of a patient in their 40s is considering withdrawing care.

States of Texas and Florida both reported record high deaths from COVID-19 on Thursday, as states in the south and west of the U.S. continue to bear the brunt of the pandemic.
https://www.newsweek.com/record-coronavirus-deaths-reported-texas-florida-1518617

Florida reported 156 new Coronavirus deaths and nearly 14,000 new cases on July 16, with fatalities from the disease in the state having increased significantly since the end of June and beginning of July, according to the COVID Tracking Project.

On July 1, the seven-day moving average of deaths in the state was 38, whereas on July 16 the figure was 95, according to the Johns Hopkins Coronavirus Resource Center.

 

[BWV]

The link between blood type and Covid-19 is BS

Native Americans are nearly 100% type O, yet Covid-19 rages across Latin America and threatens to wipe out indigenous groups in the Amazon.

and this study was just published“We showed through a multi-institutional study that there is no reason to believe being a certain ABO blood type will lead to increased disease severity, which we defined as requiring intubation or leading to death,” said senior study author Anahita Dua, HMS assistant professor of surgery at Mass General.

“This evidence should help put to rest previous reports of a possible association between blood type A and a higher risk for COVID-19 infection and mortality,” Dua said.

https://hms.harvard.edu/news/covid-blood-type

 

[Astronuc]

I believe 'probable' cases are treated separately, but it's not clear how uniform and consistent the reporting is across 50 states and the 3000+ counties.

From - https://news.yahoo.com/texas-erases-covid-cases-fans-091650711.html

“The case data on our website reflect confirmed cases, and cases identified by antigen testing are considered probable cases under the national case definition,” said Chris Van Deusen, a spokesman for the Texas Department of State Health Services.

Under that definition, the CDC only considers cases “confirmed” if they are diagnosed using a molecular, often called PCR, test. Cases that are detected using antigen tests are classified as “probable.” If someone is diagnosed with an antigen test, Texas will not count their case among the state total.

The removed cases were from Bexar County, which includes San Antonio. The city’s mayor said Thursday that San Antonio was one of three cities in Texas that tracks antigen tests—and that the tests help local health officials “see the full picture” of COVID-19 in the area.

Article with map of states with and without mandatory wearing of face (nose and mouth) covering/masking.
https://finance.yahoo.com/news/coro...-that-america-needs-to-regroup-164519833.html

Coronavirus Testing Basics
https://www.fda.gov/consumers/consumer-updates/coronavirus-testing-basics

https://www.centerforhealthsecurity.org/resources/COVID-19/COVID-19-fact-sheets/200410-RT-PCR.pdf

 

[etotheipi]

Something published today: https://www.thelancet.com/lancet/article/s0140-6736(20)31604-4

Interpretation: ChAdOx1 nCoV-19 showed an acceptable safety profile, and homologous boosting increased antibody responses. These results, together with the induction of both humoral and cellular immune responses, support large-scale evaluation of this candidate vaccine in an ongoing phase 3 programme

 

[mfb]

500 people, 2-3 months since they got the vaccine, antibodies look good, no one got seriously ill but mild to moderate side effects 2-3 days after vaccination are pretty common (figure 1 B). These side effects can make it more difficult to distribute the vaccine - most people will know someone who had them.

 

[russ_watters]

Sure - analyse it through that paradigm if you like. Ultimately in a democracy the people decide.

Yes, and that's what has me upset. In most developed countries in the world, "we" have chosen to allow thousands to hundreds of thousands of deaths because of concern over a vague/undefined privacy risk. I find that despicable.

For example people are now saying, including even me, fine and arrest those just exercising their privacy to protect the rest of us. An example is those refusing to take Covid tests. That is their legal right, but the push now is, not to take away that privacy, but to fine and force them into lockdown in a hotel at their own expense. Actually the government through biosecurity legislation can force them to take the test, but do not want to go that far - yet.

Ironically, many if not most of the legal mechanisms are already in place, but are only used on a case by case basis, not wholesale. We have had examples of forced quarantines, subpoenas for contact tracing, and mandatory affirmative proof of infection status.

It's not clear the apps work without traditional contact tracing and quarantine of confirmed cases and close contacts.
[snip]
(which one may need to anyway, even if there is an app).

I don't understand -- they are at least logically equivalent, so what would be the difference that would require traditional contact tracing? What would traditional contact tracing do that the app couldn't?

Also, doesn't South Korea provide clear-cut evidence that this method works?

If traditional contact tracing is in place, then it may be possible that the app need not be compulsory. Thus for example, it appears that the contact tracing for some of the early cases in the US was very well done.

From what I've seen, the lag time of traditional contact tracing makes it basically pointless for COVID. One of the early cases in PA was quickly identified and traced, and all the contact tracing accomplished was following the tree of infection after it had already spread:
https://www.inquirer.com/health/cor...-international-travel-infection-20200428.html

Another approach is to scale that up considerably

The scale problem seems intractable to me. A few months ago people had talked about returning to contact tracing and scaling-up to hundreds of thousands of tracers in the US, but it hasn't happened.

 

[mfb]

Also, doesn't South Korea provide clear-cut evidence that this method works?

It provides evidence that this method works in South Korea and with years of preparations.

The reaction by the Japanese government is essentially non-existent (school closure, okay, and non-mandatory suggestions), but Japan got the outbreak much better under control than the US. What does that tell us? Certainly not "what works in a completely different culture must work here, too".

I have mentioned that before (e.g. in the context of Sweden): Comparisons work better the more similar the countries are.

 

[Astronuc]

The Department of Homeland Security (DHS) Science and Technology Directorate (S&T) has established the Probabilistic Analysis for National Threats Hazards and Risks (PANTHR) program to strengthen customer engagement within the homeland security enterprise by aligning chemical, biological, radiological, and nuclear (CBRN) hazard awareness and characterization activities to provide timely, accurate, and defensible decision support tools and knowledge to stakeholders. So naturally, they are studying the SARS-CoV-2 virus.

ANTHR is working on characterizing the virus responsible for the COVID-19 pandemic. The work being done will provide insight regarding how long the virus can survive on surfaces, the potential for those contaminated surfaces to infect additional individuals, and the ability of various disinfection technologies to clean these surfaces to prevent further infection/transmission.

https://www.dhs.gov/science-and-technology/panthr

DHS staff have developed two calculators to predict the viability of the virus in air and on surfaces.

Estimated Airborne Decay of SARS-CoV-2 (virus that causes COVID-19)
under a range of temperatures, relative humidity, and UV index
https://www.dhs.gov/science-and-technology/sars-airborne-calculator

Estimated Surface Decay of SARS-CoV-2 (virus that causes COVID-19)
on surfaces under a range of temperatures and relative humidity
https://www.dhs.gov/science-and-technology/sars-calculator

Airborne SARS-CoV-2 Is Rapidly Inactivated by Simulated Sunlight
https://academic.oup.com/jid/article/doi/10.1093/infdis/jiaa334/5856149

 

[russ_watters]

It provides evidence that this method works in South Korea and with years of preparations.

I'm not sure the "years of preparations" has been that big of a contributing factor. The needed legal mechanisms and the apps themselves are really simple.

The reaction by the Japanese government is essentially non-existent (school closure, okay, and non-mandatory suggestions), but Japan got the outbreak much better under control than the US. What does that tell us? Certainly not "what works in a completely different culture must work here, too".

I have mentioned that before (e.g. in the context of Sweden): Comparisons work better the more similar the countries are.

You're trying to play opposite sides of a coin here, but you're making the mirror of mistake you're accusing me of: "what works in a completely different culture won't work here because of the culture." Reality is more nuanced than the simplistic categorizations you are making here -- and for Sweden. It's really important to try to identify what factors matter about countries that make them similar or different, and not choose arbitrary or irrelevant ones, or ignore relevant ones.

If Japan and South Korea succeeded more because they have a strong culture of compliance (certainly likely a contributing factor), it makes the need for compulsory measures is greater in countries with a higher propensity toward freedom/individualism, because there's greater "room" for such measures to make a difference.

E.G., the difference between Japan and South Korea's deaths is 25%. If, as you say, they are highly comparable societies, then that difference may be explainable by the difference in approach. So one would expect the worst-case impact of such measures here to be a 25% reduction in deaths in other societies. In the US, that would be 38,000 lives saved and counting.

But what really blows my mind here is that even in the face of many thousands of deaths, people aren't even interested in trying.

 

[BillTre]

Here is a map of the proportion of people wearing masks, based on interviews, as described in this NY Times article.

Here is a map of average daily corona virus cases in the last 7 days, from the NY Times, here.

 

[mfb]

I'm not sure the "years of preparations" has been that big of a contributing factor.

I'm not sure either. That means South Korea's success doesn't imply that this would have to work elsewhere. I haven't seen a convincing argument that this infrastructure - legal and technical - could be set up in a short time. No country managed to do so.

You're trying to play opposite sides of a coin here, but you're making the mirror of mistake you're accusing me of: "what works in a completely different culture won't work here because of the culture."

I don't say that. I said that using South Korea as evidence that this must be very helpful is problematic. Maybe it would be very helpful. I don't know - and I don't claim I would.

So one would expect the worst-case impact of such measures here to be a 25% reduction in deaths in other societies.

Sorry, but that approach is absurd in every aspect.

 

[atyy]

I don't understand -- they are at least logically equivalent, so what would be the difference that would require traditional contact tracing? What would traditional contact tracing do that the app couldn't?

One problem seems to be that distance is hard to infer using bluetooth. If we quarantine a lot of people who are not close contacts, people will think the system is crying wolf.
Inferring distance from Bluetooth signal strength: a deep dive
Why Bluetooth apps are bad at discovering new cases of COVID-19

My understanding is that in Singapore, where the spread seems to be reasonably well managed, the bluetooth app is not yet compulsory, and traditional contact tracing has been beefed up a lot. We'll probably have to wait 3 to 6 months before they release a paper on how much the app is helping with contact tracing.

I should say that the bluetooth tracing is not the only tech tool in Singapore. Everyone here has an identity card, and one's identity card number must be logged when one enters public places like malls, supermarkets and restaurants. For convenience, the logging can be done by another functionality packaged with the bluetooth app, but they are separate functions. Use of the app is not compulsory. The entry registration is compulsory, and can be done by methods other than using the app.

Here is an example of the public messaging on the bluetooth tracing (TraceTogether) and entry registration systems (SafeEntry): https://nusmedicine.nus.edu.sg/images/resources/newsinfo/Jul2020/newsinfomain_COVIDChronicles75_200718.jpg