COVID-19 contact tracing apps

[I moved this discussion out of the thread for David Shayer’s article about Apple’s privacy approach because that article is explicit about how Apple and Google’s approach is for contact exposure and notification, which is completely different from contact tracing. -Adam]

I hope people back up and reconsider the whole concept of tracing as one more step in the direction of abrogation of civil rights. What would be helpful and natural instead is a running tally % of herd immunity, presumning that anonymity could be preserved.

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Herd immunity is a complete non-starter. As long as there’s no vaccine that is very unlikely to change.

First of all we still don’t have scientific proof that prior infection renders immunity. Without that or a vaccine there is no herd immunity.

Secondly, we are incredibly far away from herd immunity. Estimates for it are that 70% have to be immune. The US so far has about 80k deaths which means there have been on the order of 24M infections in our country so far in total. Even if we now were to assume all those people are indeed immune, that is still roughly 10 times less than presumably required for herd immunity. And it’s not just us. Even in hardest hit countries like Italy, despite all the horrors and suffering, on a whole the population is still an order of magnitude away from herd immunity.

Without a vaccine, at least medium term and without accepting a huge death toll, we can completely forget about herd immunity.


We are having a pandemic - like the Black Death. People seem to be forgetting that the world has basically been shut down. The app is designed to trace interactions by people who have the misfortune to contract the COVID-19 disease. The concept behind the apps is to break the chain of transmission and so limit/stop a multiplying spread of COVID-19 disease.

Self-isolation is the only way of breaking the chain of transmission until vaccines are invented and in full production. Herd immunity from this virus is not apparent so far and it is for certain that viruses can’t be killed with semi and full auto guns.

Americans from the top down seem to have missed the facts. Americans have no more civil liberties than do people living in most western economy based countries. Some Americans seem to think that being socially and civilly responsible is not as important as this thing of ‘civil liberty’ in this pandemic.

People who complain about these COVID-19 disease tracing apps don’t seem to be giving up on their social media accounts, credit cards, bank accounts that deliver up much more private information than these apps will ever do.

I believe that it will be American science that will come to the fore with vaccines and then rapidly produce vaccines. But it is a pity that US is not showing any leadership in this pandemic.

Given the civil liberty of the American healthcare system, about half of Americans will not be able to afford the vaccine.


It’s now being more properly referred to as “COVID19 Exposure Logging,” no longer a means of “Tracing”. If you read the article, I would be interested in understanding why you consider the approach to be abrogation of anybody’s civil rights?

You might then be interested in this article that addresses just that:


Here’s why Bruce Schneier says the tracing app won’t work (basically, adoption, false positives, and false negatives).

And Steve Gibson’s followup (pp 2-3):

I live in the epicenter of the epicenter of the epicenter in New York City. My neighborhood has one highest rates of Covid 19 illnesses and deaths in the US. I live in the top floor of a high rise apartment complex, and there are only two ways I, and the other tenants in about 300 apartments can exit or enter the building, do laundry, dump garbage, and collect mail in windowless areas, by elevator or windowless fire stairs.

There have been at least two people who have been hospitalized that we know of (HIPPA laws prevent notification to people other than those who are in close contact), and some families are under quarantine for Covid 19 in the building. Since my husband and I, as well as all of our neighbors, are putting ourselves at substantial risk every time we exit our apartments, contact tracing would enable us to minimize the risk at least a little bit. And IMHO, every little bit helps.

There is an excellent analysis about contact tracing and civil liberties during a major pandemic from U. Penn’s law school:

Here’s a recent 538 post on exactly this issue. To date, 1 in 400 New Yorkers has died of Covid-19. But New York is at best now about a third of the way towards herd immunity. Who’s up for the remaining two thirds at this cost?


When I was just over a year old my mother was advised by our family doctor to take me to a hospital that was doing third stage clinical trials for children for the polio vaccine, and to get me there asap. My mother, who almost died from whopping cough when she was little, dragged me on the subway across NYC the next day and enrolled me. Polio was rampant in in the US, and especially so in areas of high density population. About 2 or 3 years later she was informed that I was one of the 50% who had gotten the live Salk vaccine.

I agree with Simon 100%. My family had relatives, neighbors and friends that had been crippled by polio. When I was in school I had classmates and friends with limps of varying severity due to polio. A former boss was in the midst of serious ballet training when she came down with polio as a young teenager. If there had more granular contact tracing, like the kind developed by Apple and Google, before the vaccine was developed and approved, it’s likely there would have been fewer cases of polio. It would have taken many more years, probably many more decades, for herd immunity to polio to develop.

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As with the polio and other vaccines for critical infectious diseases, the US makes necessary vaccines available for free, but requirements vary on a state by state basis. For kids, vaccines for major illnesses are required for school and made available for free in every school. Certain vaccines are available for free for adults and kids at public health centers as well as at drug stores, including CVS and Walgreens.

The US vaccination requirements for children had been loosened in many states for a number of years due to unrelenting and consistent pressure from anti vaxers. Due to major outbrakes of measles and other highly contagious and other potentially life threatening diseases, the states re-upped requirements lately.

My 2¢ worth from Australia, where the Federal Government has introduced COVIDSafe, a contract tracing app. Take-up has plateaued at about 20% of the population (well short of the Government’s target of 40%). Instead of not capturing any identifiable information in the first place, à la Apple and Google, COVIDSafe captures personal information and – get this – stores it on Amazon servers in the USA, where it is legally accessible by US agencies and is arguably prone to theft by criminals and hostile governments. The Australian Government waves away any concerns by promising strict laws for use of the data. Not quite as secure as not gathering the information in the first place, and not storing it anywhere except on individual phones, but that’s all right, isn’t it? After all, “We’re all in it together.” And COVIDSafe works on iPhones only when it’s the front-most app.

I am in Bermuda. We are tiny and well off (70K population, about 20 ICU beds) but also very isolated (currently NO air service). This makes controlling the virus a very high stakes game. We have the advantage of a having a sensible Government and they jumped on this right from the start. We also have the mixed-blessing of a Westminster Parliament and British Common Law-based Constitution so people generally are very much sensitive to the idea that their rights only begin where their actions do not prejudice the rights of others; something I would submit is lacking in some other places. We now find ourselves in a similar position to New Zealand, with very little evidence of endemic community transmission. One of the smartest moves the Government made was that we have local testing capability and have now started public, on demand testing. That all said the truth is that if we are to survive we MUST allow foreign travelers to come to Bermuda without the blanket 14 day quarantines which are now the only option. We simply cannot go 6 to 24 months that way. This puts “track and trace” front and centre. My reading says that a critical parameter in TnT is the SPEED with which the tracing happens This points to the conclusion that an app is going to be crucial to our success. My inclination is heavily toward the A/G app mainly for the privacy reasons cited by many. For us, here, though this is not a discussion about the user’s rights and freedoms; it is about the lives of the others we know and live with. As a tool, TnT becomes MUCH more effective when location information is available and when that information can be made available to health authorities.
What I would put on the table is that A/G should design the app to allow it to capture of that information and also allow that information to be passed to Health Authorities. Both should certainly be under full user control and probably be enabled only when a diagnosis is verified.
Is this a compromise? Yes. But I submit that it is mine to make as a user of the app. If I am of a mind to sacrifice a part of my privacy to help my community, that seems to be my Right.


Due to vaccines usually not being 100% effective, it is in everyones interest to have most of the population vaccinated to achieve herd immunity, which is why a lot of vaccines are made available for free. If everyone is vaccinated then a vaccine for COVID-19 probably only needs to be 60 or 70% effective.

So, hackers are going to spend time trying to access data that is about a persons contacts, when that data is, I believe, encrypted. I can’t see any reason for them to do that. Even if you were able to identify people then there are a lot of reasons that people may be in close proximity.

But based on current statistics on the willingness of individuals to get currently free vaccinations, I suspect we won’t see everyone getting one. Especially with the anti-vaxxer movement.

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In Australia we have about 95% of children immunised for measles. Part of the reason we achieved that is that vaccination is linked to government payments for children and access to childcare. I expect that coronavirus vaccination may become a requirement for many jobs and things like overseas travel. Although that depends on the effectiveness of the vaccine. If 100% then it will be the non-vaccinated peoples problem.

According to the World Health Organization vaccinations need “95 percent coverage to fully protect communities against outbreaks of vaccine preventable diseases:”

Vaccines that are currently available for adults are between 85%-95% effective:

The results from the MMR vaccine for children have been skewing slightly better in the US:

But this is what is currently happening:

Get Ready For A Vaccine Information War:

COVID 19 Putting Routine Childhood Immunization In Danger:

Ken wrote “If everyone is vaccinated then a vaccine for COVID-19 probably only needs to be 60 or 70% effective.”

No one has any idea yet of how effective a covid-19 vaccine needs to be.

In many countries, unless people are herded like sheep into vaccination centers, nowhere near everyone is going to be vaccinated due to the modern anti-vaxer idiocy, which is getting worse not better. This will vary not only by country, but by local district.

It also not at all clear yet if recovering from covid gives immunity at all, let alone how long that immunity might last–weeks? months? years? If natural immunity doesn’t happen reproducibly for a long enough time period, vaccines may not work at all. It’s why there’s no vaccine for colds. There’s some evidence that at least some people can get it again after recovering from it, but since testing is still in short supply around the world and tends to give a high rate of false negatives, partly due to the difficulty of sample collection, nothing is certain. This is aggravated by current antibody tests being either total crap or tending towards significant false positives.

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There’s also the question of whether any effective vaccines will be provided free or if “big pharma” or potential patent holders will be allowed to sell them at market prices, thus disadvantaging the uninsured and lowering the immunity numbers even further.

That took a tiny step in positive directions today when this came out:

Very small sample of eight, but all had antibodies after two injections. They are combining safety and effectiveness trials to speed things up. Still two more trials scheduled for Stage 1 testing with increasing numbers of subjects. CEO projects that if everything else goes right it will be ready by January. Then production and distribution hurdles will need to be overcome.

I’ve heard at least a couple reports from leadership that free is a given for this one.