What is contact tracing?

One of the best tools we need to slow down the spread of coronavirus is, as you have surely heard, contact tracking. But what exactly is the contact track, who does it and how, and you have to worry?

In short, contact traceability helps prevent the spread of a virus by proactively finding people at higher risk than others because of potential exposure, alerting them if possible and placing them in quarantine if necessary. It is a proven technique and smartphones could help make it even more effective, but only if privacy and other concerns can be overcome.

Track contacts, from memory to RAM

Contact traceability was carried out in one way or another until the medical institution understood the nature of the contagious diseases. When a person is diagnosed with an infectious disease, they are asked who has been in contact with the previous weeks, both to determine who might have been infected by them and perhaps where they have been infected.

Until recently, however, the process has relied heavily on the lure of people who are in a very stressful situation and, until requested, they probably don’t pay particular attention to their movements and interactions.

This results in a list of contacts that is far from complete, although still very useful. If these people can be contacted and their contacts are also traced, a network of potential infections can be built without a single swab or drop of blood and lives can be saved or important resources better allocated.

You might think that everything has changed now compared to modern technology and everything else, but in fact, the track of contacts that are being made in hospitals right now is almost entirely based on the type of memory – the same that we could have used a hundred years does.

It certainly seems that the huge digital surveillance apparatus that has been assembled around us in the past decade should be able to easily perform this type of contact tracking, but in reality, it is surprisingly useless for everything except to track down what you are likely to click or buy.

While it would be nice to be able to put together a week of a contagious person from a hundred cameras scattered across the city and background location data collected from social media, the potential abuse of such a system should make us grateful that it’s not as easy as that. In other less terrible circumstances, the ability to track a person’s exact movements and interactions from their digital archive would be considered somewhat disturbing, and perhaps even criminal.

But one thing is when an unscrupulous data aggregator uses your movements and interests to target you with ads without your knowledge or consent – and yet another when people to choose to use the prohibited capabilities of everyday technology in an informed and limited way to reverse the trend of a global pandemic. And that’s what the modern track of digital contacts is meant to do.

Bluetooth beacon

All modern cell phones use wireless radios to exchange data with repeaters, Wi-Fi routers and each other. By themselves, these broadcasts are not a great way to tell where someone is or who they are close to: a Wi-Fi signal can travel reliably from 100 to 200 feet and a cellular signal can go miles. Bluetooth, on the other hand, has a reduced range, less than 30 feet for good reception and a rapidly attenuating signal which makes it unlikely that a stray contact will come from much further away.

We all know Bluetooth as the way our wireless headsets receive music from our phones, and that’s an important part of his job. But Bluetooth, by design, constantly extends and touches other Bluetooth-enabled devices: it’s how your car knows you’ve entered it or how your phone detects a smart home device nearby.

The Bluetooth chips also establish a brief contact without your knowledge with other phones and devices that you pass nearby and, if they are not recognized, they mutually delete each other from their memories as soon as possible. What if they don’t?

The type of contact tracking tested and distributed all over the world now uses Bluetooth signals very similar to those that the phone transmits and receives constantly. The difference is that it doesn’t automatically forget the other devices it comes in contact with.

Assuming that the system works properly, what would happen when a person shows up at the hospital with COVID-19 is basically just a digitally enhanced version of the manual contact track. Instead of interrogating the person’s fallible memory, they interrogate the much more reliable one than the phone, which has duly registered all the other phones that it has recently been close enough to connect to. (Anonymous, as we will see.)

Those devices – and it’s important to note that it is devised people – they would be notified in seconds that they had recently been in contact with someone who has now been diagnosed with COVID-19. The notification they will receive will contain information on what the person concerned can do next: Download an app or call a number for screening, for example, or find a nearby location for the test.

The ease, speed and completeness of this contact tracking method make it an excellent opportunity to stem the spread of the virus. So why aren’t we all using it already?

Successes and potential concerns

In fact, the track of digital contacts using the method above (or something very similar) has already been implemented with millions of seemingly successful users in East Asia, which was obviously hit by the virus before the United States and Europe.

In Singapore, the TraceTogether app was promoted by the government like official means for tracing contacts. South Korea saw the voluntary adoption of a handful of apps that monitored people known to be diagnosed. Taiwan was able to compare data from its highly centralized healthcare system with a contact tracking system that it started working on during the SARS epidemic years ago. And mainland China has implemented a variety of tracking procedures through mega-popular services such as WeChat and Alipay.

While it would be premature to draw conclusions about the effectiveness of these programs while they are still ongoing, it seems at least anecdotally to have improved the response and potentially limited the spread of the virus.

But East Asia is a very different place in the United States. we cannot simply take the Taiwan playbook and apply it here (or in Europe, or Africa, etc.), for a myriad of reasons. There are also valid questions about privacy, security and other issues that need to be answered before people, who for good reason are sceptical about the intentions of both the government and the private sector, will undergo this type of monitoring.

Right now there are a handful of efforts in the United States, the biggest profile by far is a collaboration between archives Apple and Google, who proposed a cross-platform contact tracking method that can be added to phones in the operating system.

The system they suggested uses Bluetooth as described above, but above all it does not tie it in any way to a person’s identity. A phone would have its own temporary ID number and, as soon as it came into contact with other devices, it exchanged numbers. These lists of ID numbers are collected and stored locally, not synchronized with the cloud or other. Also, the numbers change frequently, so no one can be connected to the device or location.

If it’s only if a person is determined to be infected with the virus, a hospital (not the person) is authorized to activate the contact tracking app, which will send a notification to all the ID numbers stored in the person’s phone. The notification will say that recently they were close to a person now diagnosed with COVID-19 – again, these are only ID numbers generated by a telephone and are not linked to any personal information. As discussed above, notified persons can, therefore, take any action that seems justified.

MIT has developed a system that works very similarly and that some states are starting to promote among their residents.

Of course, this simple, decentralized and apparently secure system also has its flaws; this article to the Markup offers a good overview and I have summarized them below:

  • It is opt-in. This is an advantage and a disadvantage, of course, but it means that many people can choose not to participate, limiting how complete the list of recent contacts is.
  • It is vulnerable to harmful interference. Bluetooth isn’t particularly secure, which means there are several ways in which this method could be exploited, in case an attacker was depraved enough to do it. Bluetooth signals could be collected and imitated, for example, or a phone driven through the city to “expose” it to thousands of others.
  • It could lead to false positives or negatives. In order to maintain privacy, notifications sent to others would contain a minimum of information, leading them to wonder when and how they might have been exposed. There will be no details such as “you have been close to this person in line 4 days ago for about 5 minutes” or “you have passed this person on Broadway”. This lack of detail can panic people and rush to the emergency room without reason or ignore the alert altogether.
  • It is rather anonymous, but nothing is really anonymous. Although systems seem to work with a minimum of data, they could still be used for nefarious purposes if someone gets their hands on them. The de-anonymization of large data sets is practically an entire study domain in data science now and it is possible that these records, however anonymous they appear, may be cross-referenced with other data to exclude infected people or otherwise invade their privacy.
  • It is not clear what happens to the data. Will these data be given to health authorities later? Will it be sold to advertisers? Will researchers be able to access it and how will they be controlled? Questions like these could be answered satisfactorily, but right now it’s a bit of a mystery.

Tracking contacts is an important part of the effort to curb the spread of coronavirus and whatever method or platform you decide on in your area – it can be a different state to declare or even between cities – it is important that as many people as possible take part to make it as effective as possible.

There are risks, yes, but the risks are relatively minor and the benefits would seem to outweigh them. When the time comes to join, it is out of consideration for the community at large that the decision should be made to do so.

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