SINGAPORE - No breach in operations has yet been discovered at the Mandarin Orchard Singapore hotel, where several Covid-19 cases who had served their stay-home notices (SHN) are suspected to be linked, said Minister for Education Lawrence Wong on Tuesday (Dec 22).

But "what happened in Mandarin Orchard is yet another reminder that things can go wrong", said Mr Wong, who co-chairs a multi-ministry task force tackling the coronavirus here.

On Saturday, the Ministry of Health (MOH) had said that it was probing 13 coronavirus cases among people who had served their SHN at Mandarin Orchard.

The cases, which came from 10 different countries, were infected by coronavirus strains with "high genetic similarity", which implied that the infections might have come from one source.

As at Monday, 11 Mandarin Orchard staff tested positive for serological tests for the virus and this indicates likely past infections of Covid-19.

MOH also tested 571 staff of Mandarin Orchard, and all the polymerase chain reaction (PCR) test results came back negative for Covid-19. This means there is no ongoing infection among staff of the hotel.

Speaking to reporters on Tuesday, Mr Wong said that Singapore's SHN regime has, by and large, been effective.

"We have had many, many months of experience with SHN," he said, adding that hotel operators have been responsible.

"They have taken it upon themselves to ensure that protocols, security, everything is done properly. In this case, we did not detect a breach yet. But somehow, something... happened. We don't quite know what is it."

Investigations into the matter will continue be carried out and Mr Wong said that there are many possible ways the virus could have spread in the incident, such as through surfaces or hotel staff.

"No one knows, but it shows you how easily... the virus can spread," he added.

"And that's why, once again, all of us need to take this seriously and remind ourselves why we should stay vigilant, stay alert and keep our guard up."

Addressing concerns about hotels being used as SHN facilities for travellers entering Singapore while being open for staycations to hotel guests, Mr Wong said that the operations for areas in Mandarin Orchard used for SHN and holidaymakers are kept separate.

The wing of the hotel that houses those on SHN is separate from the wing that houses those on staycations. The SHN wing is also separate from other areas of the hotel open to locals and members of the public, said Mr Wong.

"Protocols (and) safety arrangements are already put in place," he added.