TORONTO -- Walk up to the store. Open an app on your phone. Scan a QR code outside the entrance.

Wait for your temperature to be taken. Get the OK. Enter the store. Make your purchase.

Leave the store. Open the app again. Scan another QR code. Head home.

This is how contact tracing works in Wuhan, China.

The system can be seen in action in a video posted to Twitter on Sunday by an anonymous British man living in Wuhan.


The epicentre of the COVID-19 pandemic, Wuhan has played host to roughly five out of every six reported coronavirus-related deaths in China.

After going more than a month without recording a single new case of the virus, a cluster of six infected people was discovered last weekend. The Chinese government is now attempting to test all 11 million residents of Wuhan for the virus in a 10-day period.

Despite that uncertainty, Wuhan remains out of lockdown, with its healthy denizens able to leave their homes and visit shops and parks – albeit with constant reminders that the pandemic is not entirely history just yet.

More than 100 Chinese cities are using the QR code system shown in the video to ensure that only those who are not sick are going out in public.

The video shows its creator using the app to check in outside a store in his neighbourhood. The app displays a green thumbprint, signifying that he is able to do so. Anyone with a yellow thumbprint needs to self-quarantine at home, and anyone with a red thumbprint must stay under supervised quarantine.

After the video's creator holds his phone up to the QR code outside the shop, a beep is heard as his temperature is taken. The reading is satisfactory, and he is allowed to proceed inside. When he leaves the store, he scans a QR code to signify that he is done there. Timestamps are recorded for both scans.

According to the South China Morning Post, more than 100 Chinese cities are now using the app, which is available in English and contains a separate section for residents of mainland China than it does for foreigners and residents of Taiwan, Macau and Hong Kong.


Having a substantial contact tracing program in place is commonly considered a necessity for nations emerging from the worst of the COVID-19 pandemic and looking to reopen their societies.

The worry is that without the ability to quickly determine who may have been exposed to a newly-detected COVID-19 patient, and then test them, the novel coronavirus will once again be able to spread through a population unchecked, setting back recovery efforts.

Dr. Michael Ryan, the World Health Organization's emergencies chief, has compared attempting to reopen a coronavirus-ravaged society without contact tracing to driving a car with eyes closed.

Contact tracing apps typically work by accessing smart devices' Bluetooth signals and using them to determine when two people were in close enough contact for virus transmission to be possible.

Although concerns have been voiced about what extending state surveillance to that level will mean for individual privacy, many countries have argued that the risks of not tracing citizens' contacts are high enough to override those worries.

In most of Europe, the debate is no longer over whether the technology is acceptable but instead where the data should be stored – with authorities in Germany and elsewhere attempting to compromise on privacy fears by choosing "decentralized" approaches. In these decentralized systems, information on a person's movements is left on their device unless they test positive for COVID-19, unlike "centralized" systems where every morsel of data ends up on a central server.

Prime Minister Justin Trudeau and Canada's premiers have discussed setting up a contact tracing system that reaches beyond provincial borders. Though there is not yet any such arrangement in place, the federal government is looking into dozens of systems, attempting to gauge both their effectiveness at contact tracing and their effects on personal privacy.