One option involves allowing users of the LeaveHomeSafe app to transfer their visited locations to Hong Kong's health code. Such transfer would require authorization by users, Sit said in a TV interview.

The existing health code system allows users to upload their negative Covid-19 test results and health declarations.

Among the options for its upgrade, the Hong Kong government suggested that citizens can record their whereabouts manually. Or the government can make a list of high risk locations, and citizens can check if they have visited such places.

Sit said it is “not impossible” for Hong Kong to launch a health code with the same functions as mainland, meaning people would be required to scan codes whenever they enter premises, including restaurants and shopping malls.

But different jurisdictions are subject to different social factors, he said.