Authorities have ordered Hong Kong's hundreds of thousands of foreign domestic workers to get coronavirus tests before May 9, following the discovery of an untraceable mutant strain in the community.
The government also said on Friday that it is planning to make it mandatory for helpers to be vaccinated against Covid in future.
This week, a 39-year-old helper from the Philippines has been found to be carrying a more infectious variant of the virus.
Her infection has prompted the authorities to put hundreds of households from Tower 11 at Caribbean Coast, Tung Chung, into quarantine for three weeks.
Health Secretary Sophia Chan said the woman had recently met up with other foreign domestic workers and because of the risk of further transmission, the territory's helpers must now be tested for the virus, noting that another helper had also earlier been found to have a mutant strain.
Helpers who had received two doses of vaccine before a fortnight ago, and any who were tested on Friday, do not need to get a test, Chan said.
Secretary for Labour and Welfare, Law Chi-kwong, said the city's 370,000 helpers are considered to be at "high risk" of coronavirus.
However, he urged them not to rush for tests in the next couple of days, but to make use of the government's test booking website.
Law also announced that the government is planning to make it compulsory in future for foreign domestic workers to be vaccinated against coronavirus in order to be allowed to sign or renew an employment contract.
"If they return to their home countries, get infected and come back, they would become a risk in preventing the virus from entering Hong Kong,” Law explained
“As a condition for getting the work visa, we don’t think it’s a harsh requirement. Of course they can choose not to work in Hong Kong.”
The jabs are not mandatory for anyone else in the territory.
Law also said officials are planning to make helpers get tested for Covid regularly, just like people who work in care homes.
“The reason [for testing helpers] is not prejudice towards any particular group,” Law said. “The consideration is about risk. The nature of their work is to look after family members and many of them are elderly.”