Category Archives: Public Health/Coronavirus

7 in 10 Americans won’t use contact-tracing apps

No surprise: More than 7 in 10 Americans won’t use contact-tracing apps, data shows | Ars Technica

With 30% agreeing to install such apps today, that means just 9% of potential contacts could be detected.

The apps have a host of real problems:

  • insufficient users to be useful. At 50% adoption, we can detect only 25% of potential contacts.
  • unreliable signal strength-based distance determination, which fails in radio signal multi-path situations
  • unable to detect when a barrier separates contacts. You sit outside at Starbucks and someone sits inside at a table. The inside person later tests positive for Covid-19. You receive a message. But they give you no indication where or when the contact occurred – so you have to go into quarantine for 14-days, delivering no benefit to anyone. This error can occur in buildings (through walls) or even between cars stopped at traffic signals or heavy traffic.
  • unable to detect “across time” contacts. Person sits on bus, coughs, gets up, exits bus, new passenger sits in coughed on seat. These apps cannot detect this. Person sits at Starbucks tables, coughs, gets up and leaves, next person sits at contaminated table. None of these parties will be in Bluetooth contact and the apps will miss these contacts.

Bluetooth-based apps are not going to be effective. Singapore pulled the plug on their app due to insufficient users. The UK has been testing a Bluetooth app that was to have rolled out nationwide in mid-May. It’s still in testing and public information about the app has gone silent; it has not been rolled out yet. Norway has an app that uses both Bluetooth and GPS data, and used a central cloud database. This app  was just ruled as violating privacy laws and has been pulled. Public health enthusiasts thought it was okay to violate privacy laws because laws do not matter to public health enthusiasts.

  • I do not plan to install a tracing app on my phone.
  • I do plan to be vaccinated as soon as vaccines are available.
  • I was sick with Covid-19-like symptoms during almost all of March. Antigen tests were not available to normal people, only those who were already hospitalized with pneumonia and to the elite (like the Governor and her husband). My doctor suggested getting an anti-body test (end of May) but I declined as the accuracy is not sufficient (when the real world incidence is very low, the number of false positives will exceed true positives), and knowing if I was sick is not, at this time, actionable information.

Norwegian Institute of Public Health cancels their smart phone tracing app due to privacy issues

One of the first national coronavirus contacts tracing apps to be launched in Europe is being suspended in Norway after the country’s data protection authority raised concerns that the software, called ‘Smittestopp’, poses a disproportionate threat to user privacy — including by continuously uploading people’s location.

Source: Norway pulls its coronavirus contacts tracing app after privacy watchdog’s warning | TechCrunch

It had been downloaded by 16% of the population over the age of 16. That means it could detect .16 x .16 or about 2% of potential contacts. It appears their app was based on location data, centrally stored, plus used the ineffective Bluetooth RSSI method of detecting potential contacts.

It appears that public health enthusiasts had used the “laws don’t matter in a pandemic excuse” to justify violation of EU privacy laws.

Smartphone tracking apps lose favor: “What happened to all the coronavirus tracking apps? – CNN”

Last week, Singapore pulled the plug on its own Bluetooth-based smart phone contact tracing app:

Covid-19 tracking apps were hailed as a way to help countries out of lockdown. Instead many have been delayed, and those that are out are not being downloaded at the rates experts say are needed to have a major effect.

Source: What happened to all the coronavirus tracking apps? – CNN

The apps cannot work unless nearly everyone in the country has a smart phone and installs the app. Furthermore, they are incapable of tracking contacts across time (scenario: sit on bus, cough, get up, leave, next person sits in seat, contacts viral load – apps miss this completely).

Lots more here on why Bluetooth-based, smart phone tracking apps are very unlikely to work well.

The U.K. is testing their own Bluetooth-based app on the Isle of Wight and news reports suggest the test is not going well. The NHS is being secretive about what they are learning. The app was originally to have been rolled out nationwide about 3 weeks ago… but for now, there are no updates on the test. Another problem is the U.K.’s system is a privacy nightmare.

Economics: Employment forecasts for May were in a different planetary system

Source: Calculated Risk: Comments on May Employment Report

Economists had forecast an additional loss of 8.3 million jobs in May, and an increase in the official unemployment estimate to 19.5%.

Actual for May: an increase of 2.5 million jobs and unemployment falling to 13.3%. Same for Canada too.

Economists and their computer models were off in space. 

Since much of the country had not yet “re-opened” after public health sociopaths flattened the economy, this is a good number. By June, many more areas are re-opening – will be interesting to see the unemployment figures for June.

Continue reading Economics: Employment forecasts for May were in a different planetary system

A thorough analysis of how mobile phone apps and location data are being used worldwide for attempts at Covid-19 tracking

The linked report is a very thorough analysis of what is being done in countries throughout the world in regards to cell phone data for Covid-19 tracking, and looks at a number of issues, particularly with regards to privacy.

Source: Mobile Location Data and Covid-19: Q&A | Human Rights Watch

I see so many problems – technology – both software and RF issues – usage scenarios, laws, privacy issues, and practical issues such as unenforceable quarantines via phone, false positives and insufficient participation and so on – that phone-based tracking apps will not provide meaningful benefits during the current calendar year.

Continue reading A thorough analysis of how mobile phone apps and location data are being used worldwide for attempts at Covid-19 tracking

Contact tracing apps do not track surface and air contacts across time

First:

Contact Tracing of Surfaces Across Time

Another problem with contact tracing apps is they cannot detect contacts across time – nor aerosolized virus and droplets handing in the air.

Some one sits on a bus seat or commuter light rail seat, coughs, putting droplets on the seat and in the air around the seat. Then gets up and leaves. Another person boards and sits in that seat and touches it with their hands. The BLE model is unable to detect this contact. Considering that the NYC subway is now thought to have been a major vector for diseases transmission, this is a serious short coming.

Another example – some one sits at a table at Starbucks, coughs at the table a few times and then leaves. 1 minute later, someone else sits at that table and touches their hands on the table, or just breathes the aerosol or droplet cloud, and later scratches their nose. The contact tracing app cannot detect surface or air contamination scenarios across time. While Starbucks might clean tables frequently, there is no guarantee.

There is no way to solve this problem using a BLE contact algorithm that does not store actual location data – the BLE tracking app only detects instantaneous “moment in time” contacts.

This week the CDC said that may be surface contamination is not a big source of infections so perhaps this is no longer a big factor.

Does it Matter? May be not?

And then perhaps none of this matters. In Utah, where they have traced the source of most Covid-19 patients’ contacts, about 60% were traced to close family contacts that had the disease and about 25% to close social contacts. That’s 85% of all traced contacts. There were not many random connection contacts leading to becoming infected. Originally, China thought about 60% were due to random contacts – but it might be appropriate to extrapolate that – from congested cities where much of the population travels via public transit – to many U.S. states (like Utah) where public transit use may be just 1-2% of the population.

Moving Further Apart Can Increase Signal Strength!

Another interesting problem with BLE-based tracking apps. They rely on the BLE 1 mw discovery process which can send a signal out to about 10 meters. They combine this with the Received Signal Strength Indicator to estimate that a contact is within about 6-7 feet. In a pure “free space” environment, signal strength can approximate distance. But the real world is not a “free space” environment.

First, if the phone is in your left pocket and you stand several feet from another person on your right, whose phone is in their right pocket, the direct path may have lost 20 db of signal strength due to your body blockage. The software thinks the two of you are far apart when you are actually standing next to each other.

Second, in the real world, radio signals do not travel in a straight line from transmitter direct to receiver. Instead, signals reflect off of objects in the environment. Some times the reflected signals arrive at the receiver in a way that increases their apparent strength and in other cases they arrive in a way that decreases their apparent strength. This is known as “multi-path”.

Think of a pond of calm water. Toss in a rock and see how the waves move across the surface. What happens when the waves strike the shore or another rock – they typically reflect or bounce back creating a new wave front. In a complex environment, there are many wave fronts traversing that water. In some places, wave heights may combine momentarily to create a higher wave, while in others they may combine to create a deeper trough.

The effect of this in the Bluetooth contact tracing app scenario is that – and this has been tested in the real world – there are real scenarios where people moving further apart see a stronger received signal strength!

The software erroneously thinks these two people have increased their risk when they are moving further apart!.

The opposite can also occur – as people move closer together, due to multipath, the devices may sense a drop in signal strength and erroneously think there is less risk.

The Need for Controlled Trials

This is why this technology must be tested in the real world before it is rolled out to entire populations. The bottom line assessment is: Does it detect actual contacts we need to worry about – without missing contacts we do need to worry about?

The Gold Standard: Does it result in an actual, measured decrease in the spread of Covid-19 and a reduction in mortality?

To answer those questions requires controlled trials, just as controlled trials are required for the use of hydroxchloroquinine in the treatment of Covid-19.

Some will argue no controlled trial is necessary as the use of the app is harmless. However, if you are periodically placed in 14-day quarantines – unnecessarily – harming your income and mental health, is that truly harmless?

If not tested, deploying smart phone contact tracing apps is a mass population medical experiment without informed consent – which is illegal in the United States. But given we are dealing with public health, laws no longer matter, of course.

Why “Covid-Tracking Apps” will probably not work

I previously wrote about covid tracking apps and that what a “tracking app” is varies tremendously by country. Please read that first.

There is another issue that crops up – and that’s the effect of conditional probability (or Bayes’ Theorem). I am still reviewing this to see if I did something wrong (I think I did do some things wrong – see Afterwordthe idea is probably sound but the calculations may be wrong) – with reasonable assumptions, phone-based covid-19 contact detection apps seem unlikely to provide a benefit.

Singapore is the only country to have used a Bluetooth-based contact app so far. At the time of this writing, the U.K. is running a trial of BLE-based tracking apps.

Singapore achieved only a 12% participation rate. (Update: as of end of May it was up to 25%, which is still too small. Consequently, Singapore cancelled the smart-phone based contact tracing app).

Continue reading Why “Covid-Tracking Apps” will probably not work

Apple-Google Bluetooth “contact tracing app” depends on widespread adoption to be useful

The biggest challenge for these apps going forward is adoption. The more phones that opt-in to the system, the more successfully it can detect how the virus spreads. Apple and Google say that getting the public to trust the apps and opt-in is critical to the effort.

Source: Three states commit to Apple-Google technology for virus tracking apps

As I explain in detail here, the Apple-Google approach will unlikely have sufficient users to be particularly valuable. If 50% of all smart phone users install the tracking apps, we will have the potential to detect just 16% of close contacts. Is that sufficient to have an impact on the spread of Covid-19?

About 80% of adults have a smart phone. If we assume all 81% have phones capable of running the software (which is not realistic as many people continue to use older phones and may not have compatible Bluetooth Low Energy hardware), then 50% of all users means 40% of adults have the app installed.

The probability of a person having the app is then 0.4. The probability of a 2nd person you meet having the app is also 0.4. The probability that you and a random person you meet both have the app is 0.4 x 0.4 or 16%. Even if all 81% have the app installed, the probability of a detectable contact is at most .81 x .81 or about 65% of the adult population. This does not include children, lowering the contactable percent even more.

Most other countries that have used phone-based contact tracing – so far – have used network-based tracking, not app-based. In network-based tracking, the network tracks the location of all cellular phones – both smart phones and dumb phones with a 100% coverage/participation rate. These systems identify contacts within about a 100 meter radius, which is too broad. But these countries follow up with a robust public health in person contact tracing operation and offer Covid-19 tests so that people are not needlessly placed in 14-day quarantines.

As you can see, the Apple-Google model is unlikely to have sufficient usage to detect many contacts.

Experts criticize ICL’s Ferguson’s Covid SIM model as garbage

Those of us who have seen Neil Ferguson’s ICL Covid sim model have the same views as this computational epidemiologist:

As Ferguson himself admits, the code was written 13 years ago, to model an influenza pandemic. This raises multiple questions: other than Ferguson’s reputation, what did the British government have at its disposal to assess the model and its implementation? How was the model validated, and what safeguards were implemented to ensure that it was correctly applied? The recent release of an improved version of the source code does not paint a favorable picture. The code is a tangled mess of undocumented steps, with no discernible overall structure. Even experienced developers would have to make a serious effort to understand it.

I’m a virologist, and modelling complex processes is part of my day-to-day work. It’s not uncommon to see long and complex code for predicting the movement of an infection in a population, but tools exist to structure and document code properly. The Imperial College effort suggests an incumbency effect: with their outstanding reputations, the college and Ferguson possessed an authority based solely on their own authority. The code on which they based their predictions would not pass a cursory review by a Ph.D. committee in computational epidemiology.

Source: Britain’s Hard Lesson About Blind Trust in Scientific Authorities

Continue reading Experts criticize ICL’s Ferguson’s Covid SIM model as garbage