People serving stay-home notice (SHN) are isolated to prevent them from transmitting the disease to anyone else should they have Covid-19.
Despite that, 13 people on SHN at the Mandarin Orchard Singapore hotel may have been infected during their stay there, given the close similarity of the genome of the virus they had been infected by.
They had come to Singapore from 10 different countries.
Experts said that there are various ways this could have happened.
Professor Ooi Eng Eong of the Duke-NUS Medical School, who specialises in emerging infectious diseases and microbiology, suggested that hotel-based transmission should be investigated and standard operating procedures should be audited for compliance.
In its statement yesterday, the Ministry of Health and the Singapore Tourism Board said: “The Government takes a serious view of any breach in protocols and will investigate and take action should there be non-compliance.”
Associate Professor Hsu Li Yang of the Saw Swee Hock School of Public Health, an infectious diseases expert by training, said that since the 13 people had served SHN between Oct 22 and Nov 11, and were confirmed to be infected between Nov 2 and Nov 11, a single source for the spread of the virus is unlikely.
He added: “If they did not encounter one another during their stay, then it could be hotel staff or fomites (objects) that formed the transmission chain.”
Whether the spread could have been through towels and bed sheets would “depend on how these were distributed after cleaning”, he said.
His colleague, Associate Professor Alex Cook, vice-dean of research at the school, pointed out that given the duration, the last of the 13 people would have checked into the hotel after the first had left. People are placed on SHN for up to 14 days.
Prof Cook added that it would be interesting to know if there was any “spatial clustering” of the 13 people, such as them staying in rooms on the same floor near one another.
Dr Asok Kurup, who chairs the Academy of Medicine’s Chapter of Infectious Disease Physicians, said aside from transmission via a member of staff or some objects, ventilation and sewage also need to be looked at as possible sources of transmission.
But due to the way the coronavirus spreads, Dr Kurup said “a human factor is more likely” to be the cause of any transmission in the hotel.