SINGAPORE — Experts at the National Centre for Infectious Diseases (NCID) announced that all COVID-19 patients who have been discharged in Singapore are cured of the coronavirus, meaning they are no longer infected and cannot spread the disease to others. At the same time, there is no guarantee that their newfound immunity to the virus will last.
As of Thursday (Feb 27), the there are 96 confirmed cases of COVID-19 in Singapore, according to the Ministry of Health (MOH). Of these, 66 have been discharged and declared “fully recovered from the infection”, and 30 are still being treated in hospitals.
The NCID noted that these discharged patients no longer carry the virus and therefore cannot pass them on to other people.
However, there are still uncertainties when it comes to COVID-19—can patients get infected with the virus more than once? And if they do recover, how long will they remain immune? Experts at NCID agree that the body’s immune response to the disease needs to be studied further.
Discharged patients who have returned for follow-up visits have been swabbed and re-screened for the virus, even if they are looking healthy. This is according to the clinical director of NCID Dr Shawn Vasoo and was first reported by The Straits Times.
Dr Vasoo was reported as saying that while it is unusual for a discharged patient to become infectious again, the NCID “will be evaluating” the matter.
Across the world, 33,345 patients have recovered from the virus and have since been discharged from hospital.
Two particular reports of discharged patients contracting COVID-19 again have since surfaced.
Japanese authorities reported on Wednesday (Feb 26) that a woman tested positive for the virus for a second time.
The 40-something-year-old woman, who hails from Osaka, Japan, first tested positive for the virus on Jan 29, recovered and was discharged on Feb 1 and tested negative on Feb 6. Since then, she developed a sore throat and chest pains and went in for testing again, this time with a positive result.
Her case is a first for Japan—a patient testing positive for coronavirus for the second time after being discharged from hospital. No further information on the case has been released.
China reported that around 14 percent of recovered and discharged patients in Guangdong province tested positive again in follow-up check-ups. This suggests that those labelled as “recovered” from the virus may still be carriers.
The virus was found in anal swabs, a method that was employed in 2003 during the SARS (severe acute respiratory syndrome) outbreak. Recovered SARS patients still had the virus in their stool about one month after they had recovered.
Dr Vasoo noted that because the virus is spread through droplets, passing on infection from stool can be avoided as long as “modern sanitation and hygiene” practices are strictly observed.
Executive director of NCID Professor Leo Yee Sin relayed to the The Straits Times how the centre ensures that discharged patients are no longer infected with the virus—doctors take nasal or throat swabs from the patients to monitor “virus-shedding”, which is whether the patient continues to release the live virus and is therefore still contagious.
Professor Leo noted that molecular testing on recovered patients should show that they have “stopped shedding the virus”, meaning that no contagious virus is released when they cough or sneeze.
For added precautions, patients who are labelled as cured are re-tested and kept in the hospital for at least one more day to await the latest test results. Professor Leo also noted that “cases who are discharged are reviewed at our clinic”.
NCID’s Dr Vasoo said that more studies need to be done to study the immune response of patients infected with the virus.
“At the moment it is unknown if patients infected by the COVID-19 will have long-lasting immunity to the virus,” he noted.