13 guests on SHN may have caught virus while at Mandarin Orchard

Thirteen people, who had been classified as imported cases when they were confirmed to have Covid-19 last month, and had served their stay-home notice (SHN) at the Mandarin Orchard Singapore hotel, may have been infected after they arrived here.

The incident has resulted in all hotel guests being progressively checked out of Mandarin Orchard, about 500 staff being tested for Covid-19, and the hotel being deep-cleaned and disinfected.

But experts said the matter is unlikely to spark a wave of infections here, given that more than a month has passed since they were confirmed to have Covid-19. That would have been enough for two incubation periods of 14 days each.

The reason the 13 people are suspected to have been infected here is that they had flown in from 10 different countries - such as the United States, South Korea, Britain, the Philippines and Bahrain - but have been infected by coronaviruses that have "high genetic similarity", implying that the infections may have come from one source.

The 13 guests had also all served their SHN in the same tower of the hotel between Oct 22 and Nov 11, and were confirmed to have Covid-19 between Nov 2 and 11.

In a joint statement yesterday, the Ministry of Health (MOH) and the Singapore Tourism Board said: "This suggests that these cases were likely infected from a similar source."

Singapore routinely carries out genome sequencing and phylogenetic analysis of the virus - which tracks the family tree of the virus - from all confirmed cases. This normally takes about four weeks.

Once the link between the 13 cases surfaced, MOH looked deeper into the situation to see if transmission could have occurred locally, instead of before these people arrived here. The authorities said: "From MOH's preliminary investigations, we cannot exclude that transmissions could have occurred at Mandarin Orchard Singapore." Genome sequencing and analysis are continuing for cases beyond Nov 11, they added.

MOH said it will now test all who are currently serving SHN at the Mandarin Orchard for Covid-19, instead of doing the test towards the end of their 14 days of SHN. Most have been tested.

It is also asking all guests who had stayed at the hotel since Nov 11 to monitor their health closely for 14 days from the last date of their stay. They should see a doctor if they develop symptoms such as a cough, sore throat, runny nose, fever and loss of taste or smell.

Although people serving SHN are housed in the 446 rooms on 28 floors of the hotel's Main Tower - segregated from the other tower called the Orchard Wing - the hotel said it will check everyone out by today as a precaution.

The Mandarin Orchard incident surfaced even as Prime Minister Lee Hsien Loong recently announced that Singapore will further ease Covid-19 measures from Dec 28, due to the low rate of local transmission. This includes allowing eight people to dine out together, up from the current five.

Associate Professor Alex Cook of the NUS Saw Swee Hock School of Public Health, who specialises in biostatistics and modelling, does not think the possible spread of the virus at the hotel would derail this.

He said: "I'd be surprised if there was substantial undetected local spread between then and now."