More than 2 million Australians have downloaded the Government's COVID-19 tracing app, COVIDSafe.

The announcement the app was in development kickstarted a national debate over privacy safeguards, and the app's launch on Sunday prompted further questions about functionality.

With almost every country in the world grappling with ways to manage the coronavirus spread, many other nations are deploying similar digital contact-tracing tools.

So what do the tracing technologies look like in other countries, and what lessons can Australia learn from their rollout?

Singapore

We've all heard of the lessons heeded from the rollout of Singapore's Bluetooth-based tracing app, TraceTogether, on which COVIDSafe was partially modelled.

On Sunday, Health Minister Greg Hunt cited aspects of Singapore's model as a cautionary tale of what not to do.

iPhone issues plagued Singapore's app, with the app required to be in the foreground on an unlocked iPhone to work efficiently.

TraceTogether has reportedly been downloaded by less than 20 per cent of the country, and its Apple App Store page is littered with reviews that complain of not being able to take phone calls while allowing the app to properly function.

Australia "had the benefit of seeing what happened [in Singapore]," Mr Hunt said, and has "been able to work to ensure that that is not an issue in Australia".

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United Kingdom

The UK Government has announced its own contact-tracing app is undergoing testing and will likely be available by mid-May.

Its app will give users the option of more active interaction with the technology than the Australian version offers, with app users who feel sick invited to log their symptoms within the app.

A yellow warning notification will then be sent to app users who have been in close contact with that person.

If that person is subsequently cleared of COVID-19, their close contacts will be sent a notification saying "You're OK right now".

However, if that person is confirmed to have coronavirus, a red warning notification will be distributed, telling close contacts "You need to isolate yourself and stay at home".

China

China's use of technology to control the coronavirus spread extends to many aspects of daily life, Reuters reports.

China is using QR technology to determine admission into public places. ( Reuters: Carlos Garcia Rawlins )

Signs displaying Quick Response (QR) codes are displayed at public checkpoints, including office buildings, shopping centres, bus and train stations, and airports.

Users are required to scan the QR code with their phones and wait for their devices to display a colour-coded signal to determine whether they can pass.

A green code allows the user unrestricted movement, while a yellow or orange code requires seven days of quarantine.

If the code returned is red, the user is determined to be either a confirmed case of COVID-19 or a close contact, and must be placed in isolation.

As well as controlling people's movement, the app also has contact-tracing mechanisms in place to notify users if they come into contact with infected people.

South Korea

One of the first countries after China to experience a surge in coronavirus cases, South Korea's Government has been deploying a series of digital-tracing tools since March.

Using mobile phone location data, along with the country's prolific CCTV and credit card transaction records, authorities retrospectively track the movements of people who later test positive.

Because the technology uses GPS location data, and phone companies in South Korea require all customers to provide their real names and national government registration numbers, it's effectively impossible to avoid being tracked if you own a smartphone.

The routes taken by people later confirmed as infected are often published online, while an alert — similar to a bushfire or flood alert we might receive in Australia — is pushed to the phones of people who had visited the same locations.

After some users subject to quarantine requirements reportedly flouted tracking systems by simply leaving their phones at home, authorities announced plans to ask repeat offenders to begin wearing tracking wristbands.

The practice of authorities accessing mobile phone location data purely for contact tracing is not legal in Australia.

In Australia, the Government can apply to telecommunications companies to request access to this data for the purposes of law enforcement, national security, and protecting public revenue.

Taiwan

Taiwan is not yet using a contact-tracing app, but authorities are also using location-based technology to enforce quarantine.

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The location data of anyone required to quarantine at home is monitored to ensure compliance.

If the device monitored is switched off for 15 minutes or longer, an alert is sent to authorities.

Users are phoned twice a day to ensure they're close to their phone and haven't left home without it.

Germany

German authorities initially backed a locally produced tracing model which was set to store data on a central server, but authorities backflipped on this plan after criticism from privacy advocates.

The country will now collaborate with Apple and Google in developing a Bluetooth tracing app that will see data stored on users' phones instead — similar to the model used in Australia.

German authorities have stressed the tool will be strictly voluntary, and will alert smartphone users when they've been in contact with someone infected.

Israel

Israeli authorities launched a contact-tracing app called The Shield at the end of March, which had been downloaded by 1.5 million users as of the beginning of April, as reported by Reuters.

The app is similar to the Australian version in that it stores users' data on their devices, and users who are subsequently diagnosed with coronavirus must decide whether to release their location data to authorities.

Israeli authorities were also initially using phone location data to monitor the movements of potential virus carriers, until the practice was halted due to privacy concerns.

Hong Kong

Hong Kong uses similar technology to enforce quarantine, with users required to wear a wristband with a unique QR code that pairs to their smartphone.

Users download an app called StayHomeSafe, which uses geofencing technology to track their movements.

At random points throughout the day, the user is required to use their phone to scan their wristband, to ensure the user hasn't left the house without their phone.