At the entrance to a wet market in Tseung Kwan O, a senior couple took out their phones and scanned the QR code with their LeaveHomeSafe apps to mark their visit. But unlike previous visits, this time the app confirmed that they had been vaccinated.

The difference came as the city's "vaccine pass" program came into effect on Thursday. The program requires residents to show vaccination proof — either in electronic or paper form — before entering 23 types of regulated premises, including restaurants, supermarkets, shopping malls, and entertainment venues.

The government will do spot checks on places like malls and supermarkets. Premises such as restaurants are required to make sure that they either are vaccinated or have a medical exemption certificate.

A 35-year-old mother surnamed Fung said she will still use the vaccine-pass function to protect the family's health, although she was not approached to have her record checked when entering the wet market.