The app, Safety Guarder, was developed by PolyU's Department of Land Surveying and Geo-Informatics in three months, and is designed for use by inbound travelers when borders reopen.

Researchers say no personal data would be required when using the app.

Department head Chen Wu said contact tracing is key to effectively controlling the spread of the virus and the mobile app would serve as a possible solution.

"Our study employed a computational approach to investigate the contact tracing integrated policy across different border-reopening scenarios," Chen said.

"Built on an epidemic model with 50 percent vaccination coverage, the results suggest that scenarios with digital contact tracing can reduce the infections by 84.7 percent compared to those without contact tracing."

Their statistics also predict that there could be more than 66,000 cases in 60 days after borders are reopened.

But if there is contact tracing, the number of infections could reduce to about 10,000 cases.

If there are strict travel and social distancing measures in place, the infections can further drop 94 percent to fewer than 600 cases.

The app uses Global Navigation Satellite System, Bluetooth low-energy and data analysis technology to record the locations the user has visited. It also helps users to identify whether they have close contact with those who have tested positive for Covid-19 in the past 14 days.

Users can access pandemic information released by the government.

Chen said the app is different to the government's "LeaveHomeSafe" app, which also has contact tracing.

"The LeaveHomeSafe app requires users to voluntarily scan the QR codes at the venues to record their locations, while our app would automatically track where the users have gone using Bluetooth if the users enable the tracking function," he said.