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101: The who, what, where, when and why of COVID-19 contact tracing apps

Key takeaways

  • Contact tracing has been a key method of response by healthcare agencies and governments when it comes to COVID-19.
  • Manual tracing is slow and challenging, so digital technologies are being explored to speed up the process.
  • Responsible implementation of such technology could be a great aid in stopping the spread of novel coronavirus. 

As different countries deal with the realities of social distancing to slow the spread of COVID-19, one of the questions seemingly at the tip of every citizen’s tongue is: when will restrictions be lifted?

For governments and healthcare, it presents real challenges. Lifting measures too soon would be risking a resurgence of the virus, yet for the economy, and the patience of the population, there are drawbacks to what is being termed ‘the great lockdown’.

One of the suggestions put forward and being used by various governments, healthcare agencies and technology companies are COVID-19 contact tracing apps. But what exactly is meant by the term, and are they the panacea housebound-humans hope them to be?

Contact tracing and COVID-19

Early detection of those infected with COVID-19 is seen as a critical step in being able to stem the toll of the pandemic.1 Isolating people with the virus means it is less likely they will pass it on to others. There is a lag however, between being infected and knowing you’re infected — particularly when people may be asymptomatic. In this between time, there is the real possibility of spreading the virus.

Thus, contact tracing — identifying all the people an infected person has had contact with. Many countries have been using contact tracing to quarantine those with the virus and slow the transmission of COVID-19. But the process is akin to manual detective work. It is labour-intensive, involves interviewing sick people to find out who they’ve had contact with and then following up those people via calls and text messages.2

It’s certainly not watertight. For one thing, it is especially hard for countries with large populations, as the number of trained people needed to do the tracking can be difficult to maintain as incidences rise.3 It also takes time. In Australia, the time to contact trace is currently three days.4 Finally, it can rely on unreliable witnesses. There is no guarantee that people will remember all those they had contact with, or how to contact them. And that’s if they even know them at all (or, are honest when they’ve broken social isolation rules).

Yet contact tracing, and the ability to stop outbreaks if they occur — fast — is being seen as critical to being able to lift social distancing policies.5 The answer, potentially, could lie in the use of technology.

The who and the how of contact tracing apps


Singapore introduced a contact tracing app in March. TraceTogether, which works via Bluetooth, detects the mobile phones of people who are close by (if they also have the app installed) for later identification. If people’s phones are within two metres of each other for more than thirty minutes the app will record the data of the other user, encrypt it and keep it for the incubation period of the virus (believed to be 21 days).6 If a person tests positive to COVID-19 the data is then uploaded (with permission) to the country’s Ministry of Health, who can access the phone numbers recorded as in ‘close contact’ and let people know they’ve been exposed.

Big tech

In an unlikely pairing, Apple and Google have launched their own answer to contact tracing.7 Their interoperable APIs will be available to public health agencies for use in creating COVID-19 tracing apps.8 Similar to the Singaporean solution, the systems will use short range Bluetooth signals to exchange anonymous ‘identification keys’ with those in close contact.9 The voluntary system will notify users (via ‘key’ matching) who have been in close proximity to a person diagnosed with the virus, and, reports The Verge, users will be able to remain anonymous, without sharing name, location or other personal data.10 The apps that can use the APIs will be restricted to those developed by public health authorities. Down the track, Google and Apple want to add this contact-tracing ability as a core feature for both iOS and Android phones.

United Kingdom

In the UK, the National Health Service’s innovation unit, the NHSX, is also working on a tracing app which would allow “people who have self-diagnosed as having coronavirus [to] declare their status.”11 The system would then send an alert to users who had been in close contact for an extended period of time. If the infected person was medically tested as having COVID-19, a stronger alert would be sent telling the user to go into isolation. To prove that the initial user had tested positive, they would enter a verification code of their positive status. The NHS has said they will look at integrating the new Google/Apple APIs into their app now that it has become a possibility.


The Australian Federal Government has also released an app, COVIDSafe, based on Singapore’s TraceTogether app (which the Singaporean government decided to open-source).12 Doing so, says Australia’s Chief Medical Officer Brendan Murphy, may allow the relaxation of lockdown measures, something only possible if “there is absolute confidence that there is a really good public health response system capable of “aggressively” locking down outbreaks.”  The app is voluntary in basis, but according to the ABC, the Government says that at least 40 percent of Australians would need to sign up for it to be effective (and presumably, be considered a factor in lifting restrictions).13 In Singapore, there has been difficulty in getting a critical mass signed-up.14 15 But encouragingly, in the week since release, over 4.5 million Australians, or 18 percent of the population, have downloaded the app.16

Responsible implementation for success

As with any technology, privacy concerns are front of mind for developers and users. Singapore’s TraceTogether relies on users providing consent to participate in the setup and upload of data, and its maker, GovTech, says that no other data — such as name, location, contact list or address books — is collected. The data is stored locally on a user’s phone via cryptographically generated IDs.17

Because these apps use Bluetooth, not location data, only relative locations to contacts is recorded, not the exact place a user was. Data can, however, be uploaded to a central authority in the case of a positive test — to enable the tracing to happen —  and this is one of the potential concerns that Apple and Google say they are addressing with their solution, alongside user privacy: because data via their APIs will be relayed by servers run by health organisations, not a centralised government authority.18

The good news is that most governments have gone to great lengths to reassure citizens their privacy is being considered. Indeed, the Australian Prime Minister went so far as to tell citizens that, “the Commonwealth can’t access the data, no government agency at the Commonwealth level, not the tax office, not government services, not Centrelink, not Home Affairs, not Department of Education — the Commonwealth will have no access to that data.”19

A cause for hope

It’s fair to say that there are potential technical limitations to tracing apps dependent on the type implemented. For those that allow self-reporting of COVID-19 infection, the potential for trolling and false reports could prove disruptive to true tracing efforts.20 False negatives or positives (such as bluetooth detecting other users through walls for instance) could be possible.21 Not everyone has a smartphone, nor is capable of using one. And of course in general, contact tracing is not a preventative measure, only a reactive one.22

Regardless, there is currently no silver-bullet when it comes to responding to the COVID-19 virus, and semi-automated contact tracing — whether at the country or even an organisational level — could prove beneficial, especially for those in isolation that wish, at the appropriate time, to start unlocking doors. As part of a range of methods countries are implementing around the world to protect their people from COVID-19, technology that helps automate manual processes to increase their effectiveness are undoubtedly a tap in the right direction.