COVID-19 patients in Singapore who are clinically well 21 days after infection to be discharged

Wong Casandra
Senior Reporter

SINGAPORE — All COVID-19 patients in Singapore who are clinically well 21 days after getting sick will now be discharged from hospitals or community care facilities without the need for further swabs tests, said Health Minister Gan Kim Yong on Thursday (28 May).

However, they must spend a further seven days at their homes – or other places of residence like dormitories – to rest and recover, before going back to work.

Previously, they will only be discharged after testing negative twice for polymerase chain reaction (PCR) tests, or swab tests, regardless of the length of hospitalisation or their stay in facilities.

This revised approach, from transmission-based to time-based discharge, “will allow recovered patients while well and no longer infectious, to return to the community in a timely manner”, said Gan at a virtual press conference helmed by the COVID-19 multi-ministry taskforce co-chaired by him.

This revision, however, will not be applied to patients who have a history of being immunocompromised, said the Ministry of Health (MOH). Such patients will still require two negative PCR tests before discharge, as they may still continue to shed viable virus for prolonged periods because of their impaired immunity.

“As we know more about COVID-19, as a result of global and local research, we will adjust our medical plans for our patients,” noted Gan.

He cited a position paper released by the National Centre for Infectious Diseases (NCID) and the Academy of Medicine's Chapter of Infectious Disease Physicians last Saturday, in which findings showed that most COVID-19 patients were no longer infectious after 11 days of getting sick, despite testing positive.

Gan also spoke briefly about the World Health Organisation (WHO)’s recommendation, issued on Wednesday, for authorities to shift from transmission-based to time-based discharge. In it, the WHO said patients who are clinically well can now be discharged after 10 days from the onset of illness, as well as at least three days without respiratory symptoms or fever.

Various countries that adopt or recommend a time-based discharge policy include South Korea, United Kingdom, United States, Estonia, and Ireland, said the MOH.

These countries have typically discharged patients after a range of seven to 14 days after they developed symptoms, while South Korea discharges asymptomatic patients from isolation after three weeks from the date of COVID-19 confirmation, it added.

NCID professor Leo Yee Sin, who was present at the press conference, shared findings from three studies conducted by the centre, which supported the conclusion in the position paper.

One studied the first 18 cases here, which showed the “virus shedding or the quantity of the virus” was the highest during the early onset of infection.

The second study analysed 766 cases in the NCID ward, whereby about 30 per cent tested negative for PCR tests by the 15th day after developing symptoms, Prof Leo said. And by the 21st and 33rd day, 68 per cent tested negative and 95 per cent tested negative, respectively.

The third consisted of swab-testing 73 infected individuals on a “regular basis” and sending their respiratory samples to culture the coronavirus. When most of these patients reach the 10th to 11th day of their infection, the virus could no longer be cultured from these samples, Prof Leo added.

“So if we were to take all these scientific information together, we are confident to say that by the time they reach day 11, and by the time they reach two weeks of their clinical illness, we can no longer have any viable virus that we can culture from the respiratory sample,” she said.

Infected preschool staff believed to have fully recovered

MOH director of medical services Kenneth Mak revealed that more than 33,100 tests have been conducted for preschool staff, of which 12 tested positive, or 0.036 per cent of those tested, as of Tuesday.

“We went ahead and looked very closely at each of these test results and also performed serological tests for all 12 of these staff members,” he added.

Serological tests are blood tests that detect the presence of antibodies produced in response to the infection in the bloodstream and can indicate whether a person has been infected in the past.

Of the 12 infected staff members, 11 have tested positive in their serological tests which is indicative of past infections, while the remaining male staff’s results are pending.

Results of these tests, together with that of the PCR tests, were then critically evaluated and the evidence suggests that they were “not active, fresh infections”, said Associate Professor Mak.

“The test results, in fact, suggest that these staff members have all recovered from the infection,” he added.

“As a result, it is our evaluation and our assessment that none of these staff members are currently a risk to either other colleagues within the preschool setting or to the children that are supported and cared for by the school staff.”

The ministry is unable to say for sure exactly when they were infected, but Prof Mak said that the results imply that “sometime earlier” they were exposed to COVID-19 and became infected themselves.

He also added that all infected staff members are well, with the majority of them presenting no symptoms.

“It reaffirmed in our assessment that, prior to the circuit breaker being imposed, there was some level of community spread,” said Prof Mak.

Serological tests unreliable, say US health authorities

On Wednesday, the US Centers for Disease Control and Prevention (CDC) said in new guidance posted on its website that serological tests might be wrong “up to half the time”.

It cannot be assumed that infected patients with truly positive antibody test results are protected from future infection, the CDC said.

“Serologic testing should not be used to determine immune status in individuals until the presence, durability, and duration of immunity is established.”

The test results should also not be be used to “make decisions about grouping persons residing in or being admitted to congregate settings, such as schools, dormitories, or correctional facilities”, it added.

“Serologic test results should not be used to make decisions about returning persons to the workplace.”

The CDC’s guidance comes a month after the WHO warned that there was currently “no evidence” that people who have recovered from COVID-19 and have antibodies are protected from a second virus infection.

There are no published figures on the number of serological tests done here in Singapore. As of 25 May, the MOH has conducted 334,691 swab tests, or PCR tests, of which 218,996 were done on unique individuals.

This translates to around 58,700 swabs conducted per 1 million total population, and about 38,400 unique individuals swabbed per 1 million total population.

To date, Singapore has 33,249 COVID-19 cases, of which over half have been discharged from hospital and have fully recovered.

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