Government pandemic advisor David Hui on Monday said Covid cases in Hong Kong are bound to increase in the near future following the border reopening with the mainland, as well as the lifting of most Covid restrictions in the city.

Speaking on a radio programme a day after the resumption of quarantine-free travel with the mainland, the Chinese University respiratory medicine professor warned Hong Kong may also see an increase in severe Covid cases or even more deaths.

If that's the case, he said authorities may have to consider tightening the testing and vaccination requirement for travellers crossing the border.

Currently, they are not required to be vaccinated against Covid, and only need to obtain a negative PCR test result to do so.

“After the border reopening, we should observe whether it leads to an increase in the proportion of serious cases on both sides [of the border], because unvaccinated people are now allowed to cross [the border]. If it leads to a greater increase in the number of serious cases and deaths, maybe adjustments would be made,” Hui said.

Meanwhile, University of Hong Kong epidemiologist Ben Cowling said the latest travel arrangements with the mainland will not put pressure on the SAR's healthcare system, saying the quota in place is a key measure to control the Covid situation.

Professor Cowling said although some tourists may bring Covid with them into Hong Kong, there should not be many serious cases.

"When we see the pictures in mainland China of hospitals being full of patients, that's not full of the kind of people that will be crossing the border to Hong Kong. That's full of unvaccinated, frail, older adults - often people who can't even leave their place of residence with their living in an institutional facility," he told RTHK.

"So I don't think that there is any concern we will be flooded with very severe Covid cases."