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What is contact tracing and how is contact tracing technology being used to fight Coronavirus

What is contact tracing, how is it useful, how can it be achieved through apps and protocols? Our latest blogpost addresses this and more

Where we look at the meaning of the term contact tracing and how technology is being used to carry it out in the war against COVID-19

Aug 19, 2020    By Team YoungWonks *

With the Coronavirus pandemic wreaking havoc across the world, contact tracing is a term that we are hearing a lot about now. In fact, many tech companies have already worked on contact tracing apps so as to help the healthcare authorities. Yet many of us may not know what it means and why it is needed. In this blog, we shall take a look at all this and more. 

 

What is contact tracing? 

A common term in public health, contact tracing refers to the process where people who may have come into contact with an infected person are identified and subsequently, data about these contacts is collected. Tracing the contacts of infected individuals, testing them for infection, treating the infected and tracing their contacts in turn helps the public health authorities contain the spread of infection. 

This explains why contact tracing has a crucial role to play in fighting infections today. It has been resorted to against several diseases, including tuberculosis, vaccine-preventable infections like measles, sexually transmitted infections (including HIV), blood-borne infections, bacterial infections, and novel infections like SARS-CoV and SARS-CoV-2). In fact, the eradication of smallpox has more to do with contact tracing than universal immunization. Exhaustive contact tracing yielded a list of all infected people who were then isolated and their surrounding community was immunized so as to contain its spread.

The goals of contact tracing are rather clear. Firstly, it is about breaking the chain of infection transmission and reducing its spread. Next is alerting all those who have been exposed to infected persons about the possibility of infection and offer preventive counseling or prophylactic care. It also aims to help prevent reinfection of the originally infected patient and to help the authorities learn about the epidemiology of a disease in a particular demographic. 

 

How does contact tracing work? 

Contact tracing typically has the following steps: 

1. A person is recognised as having a communicable disease (also called the index case). Public health authorities are informed of this case and at times, the primary health care provider continues to take charge of the patient’s treatment. 

2. The index case is thoroughly interrogated so as to glean detailed information about his/ her movements, who all they have been in close contact with.

3. As per the disease and the nature of the infection, family members, neighbours, health care providers, and anyone else who is aware of the case’s contacts can also be interviewed. 

4. These contacts of the index case are then zeroed in on by public health workers who also offer them counseling, screening, prophylaxis, and/or treatment. Contacts may be isolated (for instance, required to remain at home) or excluded (prohibited) from certain locations, say a school or a gathering,if deemed necessary for disease control. 

5. If contacts are not individually identifiable, like in cases of people attending a mass gathering, broader communication channels like media advisories can be used. 

Today, given the spread of the Coronavirus and the urgent need to reduce its spread, the need for contact tracing is more important than ever. And if we wish to lift social distancing measures like school, shop and office closures and orders to stay home, public health agencies need to carry out contact tracing a lot more aggressively. 

 

The role of technology in contact tracing 

The above reasons explain the greater need for contact tracing - especially using digital tools - today. 

 

Below are the key methods used by contact tracing technologies/ apps. 

Bluetooth proximity tracing 

Here, as the name suggests, Bluetooth, specifically Bluetooth Low Energy, is used to track encounters between two phones. Bluetooth basically transmits anonymous, time-shifting identifiers to nearby devices. Devices receiving this then add these identifiers to a locally stored contact history record. Bluetooth protocols with encryption offer privacy protection and usually do not take up a lot of battery power either. 

However, in this type of contact tracing, the user’s location cannot be tracked since it is not logged as part of the protocol. So such a system on its own won’t be able to track patients who may have become infected by being exposed to a surface touched by a patient. Another problem here is the potential inaccuracy of Bluetooth; it is not 100 percent reliable when it comes to detecting contact events.

 

Location tracking 

Location tracking can be carried out through cell phone tower networks or using GPS. A contact tracing protocol of this type was first used in Israel. Cell phone tower network-based location tracking also rules out the need to download an app. 

On the other hand, GPS logging contact tracing protocols are more private than Bluetooth based ones since the GPS can be passively logged by smartphones. 

 

GEO-QR code tagging 

This is a contact tracing technique where a venue or a place is assigned to a QR code and people scan the QR code with their phones in order to tag their visits to the place. This is thus a method of voluntary online check in and check out from the said location and users have control over their privacy, plus they do not need to download any app.

If a positive COVID-19 case is identified later, the system will be able to look for and detect possible encounters within the venues that are registered on the system with their respective QR codes. This method has been used in Malaysia by their government and in Australia and New Zealand by private sector parties. 

 

Leading contact tracing protocols today 

Contact tracing app protocols then are essentially frameworks that rely on digital tracking systems, as shared above. They typically work through mobile devices so as to establish and record contact between an infected patient and a user. Since the outbreak of the COVID19 pandemic, many non-standard protocols have been developed to aid large-scale digital contact tracing. Among these, ENS and BlueTrace are the most notable ones.  

Exposure Notifications System (ENS) is a framework and specification aimed at aiding digital contact tracing during the COVID-19 pandemic. Developed by tech giants Apple and Google and originally called the Privacy-Preserving Contact Tracing Project, the framework improves upon more traditional contact tracing techniques hitherto used by health authorities by automatically recording contacts with other ENS users using their Android or iOS smartphones. Essentially a decentralized reporting based protocol, ENS dwells on a combination of Bluetooth Low Energy technology and privacy-preserving cryptography. It is being used as an optional feature within COVID-19 apps developed and published by authorized health authorities. Launched on April 10, 2020, it was first made available on iOS on May 20, 2020 as part of the iOS 13.5 update. 

The first country to release an app using ENS is Switzerland which did so in May this year.  Several other countries have followed suit and among these, the ones released in Ireland and Germany, called Covid Tracker app and Corona Warn-App respectively, are ranked high by the MIT Technology Review’s Covid Tracing Tracker, a project that monitors the development and rollout of contract tracing apps across the world.

While 37% of Ireland’s population downloaded their Covid Tracker app in the very first week since the launch, Germany’s app has been downloaded by more than 20% of citizens, also considered to be a fairly impressive percentage of adoption.

Meanwhile, in the US, a nationwide app seems unlikely and states are planning to roll out individual apps using ENS, with Virginia now the first state to make use of the protocol. 

 

Another popular contact tracing protocol is BlueTrace. An open-source application protocol, it relies heavily on preserving privacy and co-operation of health authorities. To begin with, personal information is collected only once at the point of registration and is only used to get in touch with potentially infected patients. Users have the option to drop out at any point, allowing them to delete all personal information and ensure that previously recorded data is untraceable. Contact tracing is done fully locally on a client device using Bluetooth Low Energy, which stores all encounters for the past 21 days in a contact history log. Users in the contact log are then zeroed upon using anonymous time-shifting temporary IDs issued by the health authority. This ensures that a user’s identity can only be confirmed by their respective health authority. 

With temporary IDs changing regularly, the information is also protected against third parties. So when a user tests positive for infection, the health authority asks for the contact log. Only if and when the user chooses to share his / her encounter log, it is sent to the health authority who can then match the temporary ID with the contact information. 

The BlueTrace protocol was developed by the Singapore government for their TraceTogether app and now it has already found a taker in Australia with New Zealand also likely to use it. 

 

Contact tracing using badges 

Contact tracing badges are also being used to maintain social distancing between workers who have had return to work during the pandemic. For instance, Fleetwood Group Inc, an electronics and furniture manufacturer, has come up with what it calls Instant-Trace badges; the company says that these will be particularly useful at manufacturing facilities, fulfillment areas and for general contractors.

Costing $99 each, the employees basically wear these badges near the chest or the hip; the badges are said to vibrate and blink when social distances are not maintained. Upon the end of a shift, employees scan the QR code on the badge at a kiosk that stores the data. The contact-tracing information thus collected can be accessed by company leaders using the Internet; the info is typically stored for up to 21 days thereby helping establish the chain of contacts. 

Another such example would be that created by wearable technology company Proxfinity. It has come up with what it has named ResCUE, essentially a contact tracing platform aimed to help companies and organizations track if social distancing is being followed in the workplace in real-time. 

Here, employees simply wear the smart badge around their neck or in their pocket. The badge then gets activated only upon coming within a certain distance of another badge; it then records when the distance limit was breached and for how long. Through a personalized dashboard, Proxfinity’s backend platform analyzes this data. ResCUE badges have a battery life of 3-5 days and they store data independently by syncing with the cloud-based SaaS backend when secure WiFi is available or when docked.  The badges and the data can be anonymized and do not require personally-identifiable information to function. 

Thus, these ResCUE badges act as SaaS (Software as a Service)-powered wearable devices that let companies know about the potential level of coronavirus exposure among their employees. They claim to be a better quality and more private alternative to the contact tracing protocols mentioned earlier, that typically depend on personal devices, app downloads, GPS, always-on WiFi or Bluetooth.

 

Threats associated with contact tracing 

Contact tracing in matters of public health is no doubt needed now more than ever before, but it is also important to acknowledge the fact that it doesn’t come without any perils attached. As a matter of fact, it is encumbered by ethical constraints. The biggest issue is the loss of privacy. 

There is a lot of scope for it to be abused wherein raw location data is made available to the authorities, in turn subjecting individuals’ personal/ professional lives to unwarranted scrutiny. For instance, the issue with Bluetooth-based solutions is that smartphones continuously sending RF signals every 200ms can be spied on. Also, a system relying just on Bluetooth is not too dependable in any case, since the likelihood of so many users having it on is also not that high right now. 

Similarly, digital contact tracing solutions that ask users to share their location trails to a central system without encryption are also exposed to security threats. The BlueTrace and Pan-European Privacy-Preserving Proximity Tracing (PEPP-PT) contact tracing protocols, for instance, use centralised report processing, which can come in the way of ensuring privacy. Such centralised report processing protocols need users to upload their entire contact log to a health authority administered server, which means if the health authority fails to maintain security on its server, all the user info is under threat. 

The PEPP-PT in fact deserves a special mention here. A full-stack open protocol, it was created to help with digital contact tracing of those infected by the Coronavirus. It uses Bluetooth Low Energy to find and locally log clients near a user. It then sends this log for each user to a centralized reporting server and offers the advantages of keeping humans-in-the-loop and allowing for health authority verification. But the big downside here is the loss of privacy. It is said that users do not have to register with their real names but the fact remains that the back-end server can process pseudonymous personal data leaving it vulnerable to cyber attacks.

 

The bottomline remains this: privacy protection, regardless of the contact tracing app protocol being deployed, is imperative. Recognising this will ensure that the information gleaned is used only to protect public health and once the pandemic is behind us, we will have not handed over all our information to the government authorities. Contact tracing apps thus need to factor in this need to not violate privacy - as far as possible, anyway - even as they perform efficient contact tracing. 

 

*Contributors: Written by Vidya Prabhu; Lead image by: Leonel Cruz

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