SINGAPORE - All coronavirus patients who are assessed to be clinically well and no longer infectious by day 21 of their illness will be discharged without having to undergo further tests, said Health Minister Gan Kim Yong on Thursday (May 28).
As a further precaution, these patients must stay at home or in their dormitories for a further seven days until day 28, he added. After this, they will be able to return to work.
"This revised approach will allow patients who are well and not infectious to return to the community," Mr Gan said at a press conference.
These changes to the discharge criteria for Covid-19 patients will take effect immediately. However, they will not apply to patients with impaired immune systems, who may continue to shed viable virus for a prolonged period.
Previously, patients needed two negative swab tests, 24 hours apart, in order to be discharged, even if they had not been sick for some time.
But a local study has shown that while patients may continue to test positive for some time, the virus is no longer viable after 11 days of a person getting sick and cannot be spread to others.
The findings were revealed in a position paper by the National Centre for Infectious Diseases (NCID) and the Academy of Medicine's Chapter of Infectious Disease Physicians.
NCID executive director Leo Yee Sin, who was at the press conference, highlighted three local studies on the virus.
The first, involving 18 coronavirus patients, showed that virus shedding is highest during the early onset of clinical illness.
Another study, which looked at 766 cases, found that three in 10 patients cleared the polymerase chain reaction test by day 15, with nearly seven in 10 doing so by day 21.
By day 33, 95 per cent were able to clear their tests, Prof Leo said.
A third study found that when the viral quantity has been reduced to a certain level, the virus can no longer be cultured from a sample.
Associate Professor Kenneth Mak, the Health Ministry's director of medical services, noted the World Health Organisation on Wednesday recommended that coronavirus patients should stay isolated for at least 10 days after the onset of symptoms, and be symptom-free for another three days after that.
Singapore has decided to take the extra precaution of isolating patients for 21 days, he said.
"It is already with an abundance of caution that we have put together our protocol," Prof Mak said. "We want to take the precaution for individuals who have conditions that suppress their immune system."
Other countries have also started to make use of this time-based criteria to discharge Covid-19 patients. They include South Korea, the United Kingdom, the United States, Estonia and Ireland