4 years ago

Contact tracing app: What it does, how it works

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Coronavirus disease (Covid-19) is not as deadly as many other diseases that human history went through; it is, however, the fastest spreading infectious disease. So far, nothing has been proved useful in any medically related specialised discipline. Different non-medical and/or inter-disciplinery experts are also working to support the battle against virus.

One effective way medical practitioners, virologists, epidemiologists and authoritis concerned have developed is reporting corona symptoms and tracking the disease among members of the community. In epidemiology, this monitoring process is known as contact tracing that has proved effective in identifying those who are infected with the virus and also at higher risk of becoming infected themselves and further infecting others.

Such monitoring process, according to the World Health Organisation, has three basic steps. They are contact identification of someone who is infected with the virus, contact listing of them who got contact with an infected person, and finally contact follow-up where all the contact of the lists are being monitored for symptoms and test for signs of infection.

That process was still manual, and health workers used to find them out by investigating the infected patients. Now with the help of advanced technology, this process is automatised. It's promising because such manual tracing involves lots of human labour, and it puts the investigator at risk. To do that, however, we need some sort of recording system that can monitor and record an individual's life.

Smartphones are the best things to reach individuals. With its diverse features along with internet connectivity, everyone is already being tracked continuously by telcom providers and the likes of Google software as we move around. So, an app-based contract tracer can be developed to identify Covid-19 patients and people at risk.

Motivated by other countries, the Corona Contract Tracing app has already been launched in Bangladesh. However, it's not clear which model it has followed. Press briefing indicated that it follows the Western model, where only Bluetooth and location-based information will be used. Still this level of information is not sufficient to make it popular to be used by people.

Let's first see how such a standard smartphone-based contact tracing works. It is usually designed in a way that collects data from the users who are staying 1.5-metre proximity to each other for 20 minutes (as the COVIDsafe app in Australia works). And the minimum technology required for this is Bluetooth to detect and share proximity data, and internet to pass the data to the server.

Dwelling on how it operates, assume, in mid-June, four people - Rahim, Karim, Jabbar and Palak - installed the app. From that point, all go about their daily business life - going to office and shopping for essentials. They don't know each other, but as they move around in the community, their app is working in the background and receiving data from one another. The next week, Jabbar, hypothetically speaking, develops a cough and tests positive' for Covid-19. If he informs the health or responsible department such as IEDCR scientists, they get straight on to Jabbar for an interview. Instead of asking him common questions like where he went in the past 14 days, they would first gain access to the app database of the very precise data recorded.

Records may show Jabbar and Rahim had stood in a line at what turns out to be a supermarket for 20 minutes. One day Jabbar, Rahim, and Karim had sat next to each other in what they discovered was a doctor's waiting room for half an hour, and Palak happens to be a neighbour in Bluetooth range via shared balconies at Jabbar's apartment block. At this point, investigators would make calls to all three of them and take measures such as referring them to maintain isolation.

What the app doesn't tell them is anything about dozens of people Jabbar had been near who did not have the app installed. Since all mobile users in Bangladesh do not have smartphone sets,  a significantly large number of people may stay out of this listing, making the tracing less effective. However, contact tracing may be more effective in urban areas, where much higher number of the people possess smartphone sets. Still, such concerns need to be studied.

In Australia, contact tracing app, COVIDsafe is designed to collect name, phone number, postcode, and age range. And information on diagnosis of Covid-19 will be mapped with patients' diagnosed results in the server.

This tracing mechanism, however, is the simplest form of digital tracing system available which is developed first in Singapore. It differs from those of other countries. The app of China is supposedly taking more personal information along with location; the tracing app from Korea has even gone further and provided authorities with the ability to alert users when they've been in direct contact with a confirmed positive case.

In Bangladesh, we did not see any background study to identify the requirements, in view of our culture, capability and feasibility of such an app before its deployment. It's important to consider such factors because if people start using it, they can't make any change.

There are usual privacy and security concerns relating to hacking and sharing of phone details. From technical point of view, the government can carry out an in-depth feasibility study to assess our own constraints, culture and challenges to adopting proper measures so as to ensure usability of the digital contact tracing.

A few issues need to be addressed to ensure success of this endeavour in our Covid-19 crisis management:

  1. A legislated user access protocol that will ensure authorities concerned to get access to traced data;
  2. A storage and backup protocol that will ensure how the data will be stored and how long the data will be stored, how much of that storage is local, and how much is in the cloud;
  3. A security and privacy protocol that will say how security and privacy of the data would be ensured, what kind of encryption used and what the effect of the app is on the mobile battery;
  4. Properly declared authorities that will confirm who or how it will medically be verified that no one is infected;
  5. A legitimated way to ensure how to let others know if anyone in his/her close contact has been infected without breaching the privacy.

Unless proper research and feasibility analysis are done in our context, deploying any such app won't be able to create any positive impact that has been observed all over the world. If all the relevant information is not published and open to all, it would be difficult for the government to bring everyone under this very same umbrella. Since use of this app is optional, not mandatory, people need to be encouraged to use it.

Dr Fida Hasan is a postdoctoral research fellow at Computer Science, Queensland University of Technology, Brisbane, Australia.

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