Mainland's health code comes in three colors – red, yellow, and green in descending risk order. Only those who receive a green code can enter the mainland without quarantine.

Hong Kong will launch its version of the health code on Friday. Those who have attained an HK green code will get a QR code that stays valid for a day, which they must show to mainland immigration to convert into a Guangdong health code applicable on the mainland.

The red code goes to confirmed Covid cases, close contacts, household contacts with people who have been near a case, people in quarantine, Covid patients discharged for less than 14 days, and those who suffer from respiratory symptoms.

Sing Tao Daily, the sister publication of The Standard, reported that residents who live in the same building as a Covid patient will be given a red code.

Those who live in the same estate will be given a yellow code, while Hong Kong and mainland authorities are still discussing whether those who live within a certain perimeter in the same district will get the yellow code as well.

"Since the Hong Kong Health Code only serves the purpose of boundary-crossing but not location tracing, it cannot accurately identify those who have had contact with the confirmed cases," the source said. "In order to reduce the risk of infections, strict standards will be adopted."

The HK health code will open for registration at 9 am on Friday

Users are required to submit their personal information, including their Hong Kong identity card number and address.

They also have to upload health declaration forms and travel history in the past 21 days recorded on LeaveHomeSafe to the code, based on which they will get codes in green, yellow, or red.

To support the synchronization of such records, a new version of the LeaveHomeSafe app will be available for upgrading from Friday.

If a Hongkonger's health code changes from green to yellow or red after entering the mainland, the person concerned will have to undergo quarantines according to the mainland requirements.

Mainland experts were initially concerned about HK's health measures, given that the use of the LeaveHomeSafe app is voluntary and that it is challenging to trace close contacts of confirmed patients.

However, after visiting Hong Kong, they believed that people in Hong Kong are generally self-disciplined in disease prevention and wear masks most of the time. The implementation of compulsory testing is also satisfactory.

Therefore, Beijing was said to have given the all-clear signal to open the border with Hong Kong before Christmas as a "gift" to Hongkongers.

Secretary for Innovation and Technology Alfred Sit Wing-hang said earlier that the date and quota for the quarantine-free travel scheme have yet to be set, so people need not rush to get the code. Authorities want to publicize the system early so people can familiarize themselves with it.