SINGAPORE - Patrons who were hoping to have lunch at Seoul Garden in Tampines Mall on Friday (Nov 27) were met with closed doors and a sign that read: "We are closed. Sorry for the inconvenience caused."

The restaurant, which had been open until Thursday, will reopen on Saturday (Nov 28) after disinfection.

Last Saturday, a family of 13 had dinner there. One of them, a 32-year-old service engineer, fell ill two days later and tested positive for Covid-19 on Wednesday.

He became Singapore's first locally transmitted and unlinked Covid-19 case in 16 days.

Mr Garry Lam, Seoul Garden Group's general manager, said in a statement on Friday: "We were contacted by the Ministry of Health (MOH ) on Nov 25, requesting information as part of their contact tracing for a Covid-related case."

He added that the restaurant chain later learnt through the media on Thursday that a confirmed Covid-19 case had dined at their restaurant in Tampines Mall.

When The Straits Times visited the restaurant on Friday at around noon, two employees of professional cleaning firm Clean Solutions arrived to disinfect the area, including the food counters, windows, tables and pillars, with a high pressure jet cleaner.

"Every effort has been made to assure our customers that the restaurant is safe... and to offer them peace of mind when we reopen the outlet (on Saturday)," said Mr Lam.

Last Saturday, the service engineer was at the outlet between 5.45pm and 8.55pm.

The family had occupied three tables at Seoul Garden, and there was mingling between the groups, said MOH. It added that investigations are ongoing to assess if there has been any breach of the relevant safe management measures, and epidemiological investigations are in progress.

Seoul Garden's website states that a maximum of five people are allowed per table, and mixing between tables is not allowed, which is in line with Singapore's safe management measures.

The man's identified close contacts, including the 12 family members at the dinner, have been placed on quarantine.

Mr Lam said the family did not come to the restaurant as a group, and there were no records of a booking for 13 persons.

He added that the staff are trained to remind patrons not to mingle with other diners: "We observe that sometimes young children get restless after sitting for a long time. When they stand up to stretch their legs, we will remind them to stay at their table."

The service engineer's job at Master Systems Marine entails going on board vessels docked at Marina South Pier and West Coast Pier. He typically worked alone, except for when he interacted with a supervising crew member. On days he was not on board vessels, he remained at his office at Vertex Building Tower B in Ubi.

He reported he wore a surgical mask on board the vessels and at the office, and that safe distancing and safe management measures were adhered to, said MOH.

Master Systems Marine's branch manager, who declined to be named, told ST the company was notified of the case on Wednesday.

On Thursday evening, the company's office in 33 Ubi Avenue 3 was closed in preparation for disinfection at 1pm on Friday.

All 14 employees are working from home, and they were told to isolate themselves and stay home as much as possible, he said.

The employees are waiting for instructions from the authorities about swab tests, he added.

Meanwhile, the manager has sent his employees' details to the authorities, and will also be sending the company's continuity and disinfection plans. It has followed safety measures that include safe distancing, split-work arrangements and mask wearing, he added.

Associate Professor Alex Cook of the National University of Singapore's (NUS) Saw Swee Hock School of Public Health, said the person could have been infected on the ships where he worked or at the family dinner.

"I can only speculate about the risks on board the ships he services, but it seems quite possible that infection arose there, possibly through the supervisors he interacted with," said Prof Cook, who is the school's vice-dean of research.

"Although he wore a mask on board, the mask provides more protection to others than to the wearer, so he still might have been infected despite this precaution."

Prof Cook added that the person was more likely to have infected others at the Seoul Garden dinner rather than to have been infected there, as the dinner happened 48 hours before his symptoms started.

Professor Dale Fisher, senior consultant at the division of infectious diseases at the National University Hospital, said the case suggests Covid-19 may be "smouldering in the community and transmitting through asymptomatic cases".