As Hong Kong clocks almost two months, or 56 days, with no local coronavirus cases, its officials are rolling out a recalibrated strategy - from cutting quarantine periods for vaccinated visitors to ramping up vaccination for civil servants and school staff.

Given the new wave of cases in the world, coupled with a more infectious Delta variant, Hong Kong's Chief Executive Carrie Lam yesterday said the government's key strategy is to prevent imported cases.

Currently, all who enter Hong Kong must present negative nucleic acid test results done within 72 hours before boarding the flight, and only Hong Kong residents can enter the city if they are coming from high-risk countries.

Under the tweaked rules, non-residents from high-risk areas can also enter Hong Kong if they are fully vaccinated. For medium-risk areas, only Hong Kong residents and vaccinated non-residents can enter.

Currently, all travellers from medium-risk areas can enter Hong Kong. But all arrivals have to be quarantined in designated hotels - seven days for those from low-risk areas and up to 21 days for those from high-risk areas.

The new rules state that those from medium-risk areas can choose to take an antibody test in Hong Kong, undergo a shorter seven-day hotel quarantine and self-monitor for another seven days. On the flip side, residents who are not inoculated but entering Hong Kong will have to spend seven more days in quarantine.

For instance, if a non-vaccinated resident comes from a low-risk area, instead of having to undergo a seven-day mandatory quarantine, he will have to do 14 days.

But there was no mention of when the new rules will kick in.

Meanwhile, the government will also step up mandatory testing of all arrivals. Mrs Lam said that at most, some people would have taken seven mandatory tests within 19 days of arrival, including the ones at the airport. As for the people who deal with arrivals - such as quarantine hotel staff and transportation workers - they must all be vaccinated, she said.

The Chief Executive added that the "get vaccinated or pay for your own tests" scheme that began yesterday will also be ramped up.

Starting on Sept 1, unvaccinated civil servants will have to take the Covid-19 tests at their own expense, and those who refuse to get the jabs or be tested will face disciplinary action.

Mrs Lam said Hospital Authority staff, care home workers and staff of public schools will be next in line to be included in the scheme.

So far, 70 per cent of civil servants, 67 per cent of Hospital Authority staff, 64 per cent of staff of elderly and disabled homes, as well as 47 per cent of primary, secondary and special schools staff have been vaccinated.

Secretary for Education Kevin Yeung said that from Sept 1, all school employees and those who frequent campuses will have to get at least the first dose of vaccine or pay for their tests every two weeks. Exemptions are made for those who cannot get their shots due to health reasons.

He said resumption of full-day in-person classes can be considered when schools' vaccination rate reaches 70 per cent.

So far, 48 per cent of Hong Kong's eligible population have had their first dose while 36 per cent have had two shots.

Secretary for Food and Health Sophia Chan said the government will have unvaccinated restaurant workers at type B establishments go for more regular tests this month. Type B eateries are allowed to offer dine-in services until 10pm, with the number of patrons at each table capped at four.

Staff at these restaurants may either be vaccinated or be tested every two weeks.

"Relevant workers will have to get tested every seven days instead of 14 days, while those already vaccinated will be exempted from the requirement," said Prof Chan.

She added that the city's social distancing measures will be extended for another two weeks till Aug 18.

So far, Hong Kong has recorded more than 11,900 confirmed Covid-19 cases and 212 deaths.