The rise in cases, up 10-fold since February 1, is proving to be the biggest test for the global financial hub's "dynamic zero" policy of virus suppression, which has turned it into one of the world's most isolated cities.

Following mainland China, Hong Kong is trying to curb outbreaks as soon as possible, in contrast with many other places that are trying to "live with COVID", relying on high vaccination rates to bring protection while easing restrictions.

The fast-spreading Omicron variant is testing both approaches, though experts have said Hong Kong's strategy looks increasingly unsustainable with cases ballooning.

Leader Carrie Lam said she was "deeply sorry and anxious" as residents, including elderly and children, queued for hours at testing centres and to enter isolation facilities after daily infections doubled to a record 1161 cases on Wednesday.

Lam said the city was not able to try to live with the virus because more than 50 per cent of the elderly have not been vaccinated.

About 82 per cent of the city's residents have had at least one vaccine shot but many elderly people have been hesitant. Three elderly people have died this week from coronavirus, authorities said on Thursday.

However, vaccination rates have finally started to surge in recent days, particularly among older folk, as infections climb and even tougher anti-virus measures like vaccine passports are being put in place.

Hong Kong has reported more than 4000 infections over the past two weeks, versus just two in December, taking its tally to more than 18,000 since the outbreak began in 2020, with 216 deaths, figures that are much lower than those seen in other major cities around the world.

The city could see 28,000 new cases a day by the end of March, with its tally of deaths rising to 1000 by June, health experts from the University of Hong Kong said this week.

The experts modelled scenarios that they said indicated Hong Kong could only return to a "zero-covid" state if the entire city was locked down for two to three months.

The government declined to comment directly on speculation of a lockdown, reiterating that people needed to take all measures to contain the virus and limit social activities.

They have responded to the latest surge with the toughest suppression measures yet, despite an increasing social and economic toll on the city's 7.5 million residents.

Public gatherings of more than two people are banned from Thursday while gatherings in homes have also been restricted. The rules add to already strict measures that have forced restaurants to close from 6pm and shut most churches to schools, gyms and cinemas.

About 200,000 people in the Discovery Bay residential area, where many foreigners live, have been ordered to get tested after the government said it detected coronavirus in sewage.

Ching Tang, a 50-year old resident waiting to get vaccinated, said the pandemic has greatly affected many aspects of life.

"Some older people don't even dare to go out. They stockpile food for many days. Everyone is worried...I hope the government can do better."

Australian Associated Press