Singapore will hold off on further reopening measures while it evaluates the Omicron COVID-19 variant and will boost testing of travelers and frontline workers to reduce the risk of local transmission, authorities said on Tuesday.

“This is a prudent thing to do for now, when we are faced with a major uncertainty,” Health Minister Ong Ye Kung told a media briefing on Tuesday, adding the variant had not yet been detected locally.

Omicron variant in Sydney

Singapore’s Health Ministry said two travellers from Johannesburg who tested positive for the Omicron coronavirus variant in Sydney, had transited through Changi airport.

The two individuals left Johannesburg on November 27 on a Singapore Airlines flight and arrived at Changi on the same day for their transit flight, the Ministry said in a statement.

Both had tested negative for COVID-19 prior to departure, it added.

The Ministry said most of the travellers had remained in the transit area at Changi Airport.

Of the seven who disembarked, six had been placed on a 10-day stay at home notice, while the seventh, a close contact of an infected individual on the flight, had been quarantined.

“Contact tracing is ongoing for airport staff who may have come into transient contact with the cases,” the Ministry said.

Australian authorities said on Sunday that the two passengers who tested positive on arrival in Sydney were fully vaccinated and had been placed in isolation.

Omicron has prompted countries across the globe including the United States to limit travel from Southern Africa, where the virus was first detected.