SINGAPORE: Eight more Mandarin Orchard hotel employees are likely to have been previously infected with COVID-19, said the Ministry of Health (MOH) on Monday (Dec 21).
Their serological tests came back positive, indicating likely past infections. Together with the three announced on Sunday, 11 hotel staff members are now reported to have likely past infections.
"Epidemiological investigations of these 11 cases are in progress. In the meantime, we will test their identified close contacts as a precautionary measure, and also conduct serological tests to determine if these individuals could have been infected by them," said MOH.
This comes after Saturday's announcement that 13 COVID-19 cases who had served their stay-home notice at the hotel in November had "high genetic similarity" despite coming from different countries.
A total of 571 staff members have been tested and 570 polymerase chain reaction (PCR) test results have come back negative for COVID-19 infection.
"MOH is facilitating testing for the remaining individual who has yet to be PCR tested," said the health ministry.
All 394 people who stayed at the hotel to serve their stay-home notice have also been tested for COVID-19.
Three tested positive and were reported on Sunday, while the rest have tested negative.
Given the recent travel history of the three positive cases, the ministry said they were likely infected while overseas. But the National Public Health Laboratory will conduct genome sequencing and phylogenetic analysis to determine if they are linked to the 13 earlier cases.
POSITIVE SEROLOGICAL TEST RESULT EXCLUDED FROM CASE COUNT
The ministry said that only positive results from PCR tests are included in the case count, following the World Health Organization's criterion.
The cases that Singapore reports and includes in its case count are those who test positive through a PCR test and are assessed to have an "acute infection", in accordance with "international practice", said MOH.
"This ensures consistency in reporting cases across countries.
"The 11 (staff) cases whose serological tests have come back positive, but whose PCR test results are negative for COVID-19 infection, are therefore not included in our daily case count," said the ministry.
Travellers entering Singapore are subjected to the prevailing border measures upon entry, including stay-home notice and COVID-19 tests, where applicable, said MOH.
Hotels used as dedicated facilities for stay-home notice have strict protocols to which all travellers subjected to stay-home notice must adhere to, it added.
"Regular checks on these hotels are conducted to ensure that safe management measures are complied with, and security measures are in place.
"These measures have helped to mitigate the risk of importation and transmission, but travellers must themselves also remain vigilant, and take all precautionary measures to protect themselves and their travelling companions," said the ministry.
Mandarin Orchard hotel has also stopped accepting new guests since Saturday, when the 13 cases were reported. All existing guests checked out by 9pm on Sunday, said MOH.