Hong Kong civil servants, teachers and healthcare workers must get vaccinated against the coronavirus or pay for regular testing, the city's leader announced Monday, as her administration adopted a push into mandatory inoculations.

The finance hub is one of the few places in the world to have secured ample supplies of the coronavirus vaccine, but public take up has been lacklustre.

After six months, only 36 percent of the city's 7.5 million residents are fully vaccinated with two jabs while 48 percent have received one dose.

But infections have remained low as Hong Kong has been all but closed to non-residents for most of the last 18 months and all arrivals must undergo lengthy quarantine in designated hotels.

On Monday, chief executive Carrie Lam announced a new push to raise the city's vaccination rate by making jabs compulsory for four sectors: civil servants, healthcare workers, care home staff and school teachers.

Vaccination rates vary between those sectors -- from 70 percent among civil servants to just 47 percent among teachers.

-There is much room for improvement- Lam said.

Those who refuse vaccinations will have to be tested twice a week and pay for the cost out of their own pocketsunless they have a valid medical reason not to be inoculated.

-If people are refusing to get vaccinated for reasons that are not health related, I don't think a responsible government should tolerate that- Lam said.

The city's virus measures have kept infections down with around 12,000 cases and 200 deaths. No local infections have been recorded for more than 50 days.

But the zero Covid strategy has imposed tough economic costs on the city, once a major international transport hub, and added to a sense of complacency among the public.

Swirling distrust of the government as authorities carry out a sweeping crackdown on dissent has also compounded poor vaccine take up.

Steered by Beijing, Hong Kong's government has swung authoritarian in response to huge and often violent democracy protests two years ago.

Public gatherings and protests have been banned throughout the pandemic while scores of critics have been jailed.

Wearing masks in public is compulsory. But until now, Lam's administration stayed away from doing the same for vaccines.

Relations with some of the sectors affected by Monday's announcement are also tense.

The mandatory vaccines for teachers come two days after the government said it was severing all ties with the city's largest teaching union because its members supported the democracy movement.

Healthcare workers also played a key role in 2019's democracy protests.