The convenor of the advisory panel on Covid-19 vaccines on Saturday warned people not to be complacent, even though the number of coronavirus infections has dropped.

Speaking on a radio programme, Professor Wallace Lau said people should take the opportunity to get fully vaccinated now, adding that the easing of the pandemic may only be temporary.

Lau stressed that even if the Covid tally drops to zero, another wave of infections is still possible.

"We have seen times when the number was indeed zero. I guess it could happen, but it does not mean that another big wave will not come again just as what we have experienced," he said.

"I don't think it matters that much whether we will have a zero number or not. We had seen zero number for a long time and then we saw thousands of cases every day, so please don't be complacent."

Lau was speaking as the second stage of the government's vaccine pass scheme took effect. This means all adults must be doubled-jabbed to enter venues such as restaurants, supermarkets and shopping malls.

Those aged between 12 and 18 are required to be doubled-vaccinated too if it has been six months since they got their first jab.