Microbiologist Yuen Kwok-yung on Friday made a raft of suggestions to further relax Covid rules in Hong Kong, saying now is the best time for the city to return to normal thanks to a strong immunity barrier.

Writing in Ming Pao, he urged the government to further shorten the quarantine period for inbound travellers to five days, adding that hotel quarantine could be replaced by home quarantine in the next phase if the epidemic situation remains stable.

He also said close contacts of Covid patients could be exempt from quarantine if they are vaccinated, but they should get tested for seven consecutive days.

Speaking on a radio programme, Yuen said his research team found that Hong Kong has built a "secure" immunity barrier and should capitalise on it.

"Don't forget the barrier will crumble gradually as the level of antibodies in vaccinated people will drop. Therefore, Hong Kong has come to this stage that we're having a golden opportunity to resume to normal," he said.

"If we don't grasp this opportunity, we may see another wave of infections in the winter. That's why I said if we want to relax the rules, it's time to do it now."

He said while vaccination is of paramount importance in tackling the pandemic, a low level of virus circulation in the summer could boost people's immunity and help prevent another major outbreak in the winter.

Yuen also said the number of infections is expected to rise after Covid rules are further relaxed, but the key is to ensure the cases won't paralyse the healthcare system.

The expert added that authorities could stop reporting the daily Covid tally, which he described as "unimportant". He said hospitalisation and fatality figures are better indicators of the epidemic situation.