SINGAPORE: Twelve of the 14 workers who tested positive for COVID-19 after disembarking from a Scoot flight from Singapore to Tianjin on Aug 19 were recovered patients who were "no longer infectious", Singapore's Ministry of Health (MOH) said on Tuesday (Aug 25).
Official state media outlet Tianjin Daily, published on the website of the Tianjin Municipal People’s Government, reported between Friday and Sunday last week that 14 of its COVID-19 cases had arrived from Singapore on Scoot flight TR138 on Aug 19.
MOH said on Tuesday in response to CNA queries that 12 of the 14 workers have recovered. It added that these workers may continue to shed viral fragments for "weeks or even months" after infection, which may lead to positive polymerase chain reaction (PCR) test results.
"However, there is no evidence to suggest that these remnant viral fragments are infectious, and studies so far have failed to culture viable virus from these patient samples, indicating that these individuals are no longer infectious and are thus safe for travel," the health ministry said.
Singapore is in contact with Chinese authorities for further information about the remaining two cases, and investigations are ongoing.
"ROBUST DISCHARGE PROCESS": MOH
Singapore's discharge process for COVID-19 patients is "robust", and the guidelines are "more stringent" than those recommended by the World Health Organization (WHO), said MOH.
According to a time-based discharge criteria adopted by MOH, COVID-19 patients in Singapore who are assessed to be clinically well by day 21 of the illness can be discharged. The new criteria was announced by Health Minister Gan Kim Yong on May 28.
Previously, patients needed to test negative twice consecutively, 24 hours apart, in order to be discharged.
COVID-19 patients who are discharged under the new criteria will have to remain at home or at dormitories for another seven days before they can return to work after day 28 of their illness, Mr Gan had said.
READ: COVID-19 patients who still test positive but clinically well by day 21 of illness can be discharged
Singapore's discharge process for COVID-19 patients is based on the latest local and international clinical and scientific evidence that shows that "viable virus was not found in COVID-19 patients after the second week of illness", said MOH on Tuesday.
Under WHO guidelines, symptomatic patients may be discharged from isolation 10 days after the onset of symptoms without requiring retesting, with at least three additional days without symptoms, said MOH.
For discharging asymptomatic patients, only 10 days of isolation are needed following the first positive COVID-19 test, the ministry added.
"Singapore’s discharge criteria is therefore more stringent than WHO’s recommended guidelines," said MOH.
"Countries adopt different discharge criteria that may take into consideration factors beyond public health or scientific literature. Our discharge criteria have also been shared with the Chinese authorities."
"FIT FOR TRAVEL"
At a COVID-19 multi-ministry task force press conference last Friday, MOH's director of medical services Kenneth Mak said that a "small proportion" of workers may have "persistent shadows of non-viable viral segment fragments".
"And this is a reason why on occasion, some of these workers may, in fact, still have a positive PCR test, but all other tests done for them show that they're no longer infectious," Associate Professor Mak said in response to queries from China's CCTV.
"So, these people who are recovered are actually fit for travel and we have no problems in certifying them for travel and allowing them to board planes. We don't think there's any risk to other passengers in the plane."
CNA has approached Scoot for more information.
Under Singapore's "fast lane" arrangement with China, which started on Jun 8, approved travellers must take a COVID-19 swab test within 48 hours before departure.
Users of the fast lane between China and Singapore will bear the cost of the pre-departure PCR test, and obtain a certificate of having tested negative for the coronavirus.
Tianjin is one of the six municipalities or provinces that is covered by this arrangement.
"An approved applicant travelling from Singapore to China will undergo a PCR test and serology test after arrival in China at his/her own cost, and remain in locations designated by the local provincial or municipal government for one to two days until the test result is released," said Singapore's Ministry of Foreign Affairs and Ministry of Trade and Industry on Jun 3.
READ: Business and official travellers on Singapore-China 'fast lane' arrangement must get COVID-19 swab tests
According to reports in the Tianjin Daily, the 14 workers tested positive for COVID-19 between Aug 19 and Aug 22.
All of the workers are Chinese nationals, and 13 of them were reported as residing in Singapore. One was reported as working in Singapore since May 2019. They are aged between 37 and 51. All but three were reported to be construction workers.
Six of the travellers were classified by Chinese authorities as imported COVID-19 cases, while eight were classified as asymptomatic cases. China reports separately the numbers of locally transmitted, imported and asymptomatic cases – those who test positive for COVID-19 but do not show symptoms.
All eight asymptomatic cases did not have a fever when their temperature was recorded at Tianjin Binhai International Airport, the Tianjin Daily reported. Seven of them tested positive for COVID-19 when they were given nucleic acid tests while under quarantine.
The remaining asymptomatic case, a 37-year-old man, was given an antibody test at the airport and tested positive. He was transferred to the hospital, where a nucleic acid test on Aug 20 also came back positive.
SIX IMPORTED CASES
All six imported cases in China did not have a fever when their temperatures were recorded at Tianjin Binhai International Airport, Tianjin Daily reported.
One of them, a 43-year-old man, reported symptoms of a stuffy nose and diminished sense of smell when he arrived in Tianjin. He was given an antibody test, which came back positive for COVID-19.
The man was transferred to Tianjin Medical University Airport International Hospital, where a COVID-19 nucleic acid test and antibody test both produced positive results.
The five other imported cases did not report any COVID-19 symptoms when they arrived in Tianjin.
Of these five cases, four were given nucleic acid tests while in quarantine. The tests came back positive for COVID-19, and the workers were admitted to hospital.
One of these four workers, a 49-year-old man, had a fever of 37.3 degrees Celsius six days before his positive test result, according to the Tianjin Daily report, while another, a 48-year-old man, was reported to have diarrhoea symptoms a day before his positive test result.
The other two were classified as symptomatic COVID-19 cases after undergoing computed tomography (CT) scans of their chests.
The remaining imported case, a 41-year-old man, was given a nucleic acid test and antibody test when he arrived in Tianjin on Aug 19. The nucleic acid test came back negative, while the antibody test came back positive for COVID-19.
The man was tested again on Aug 20 and Aug 22, with the latter nasal swab nucleic acid test coming back positive for COVID-19.