Most COVID-19 patients are no longer infectious 11 days after developing symptoms of the deadly disease, according to a new study by infectious disease experts in Singapore, findings that may affect patient discharge policies.
“Active viral replication drops quickly after the first week, and viable virus was not found after the second week of illness,” the researchers wrote.
Patients with weakened immune systems are exceptions, and in such cases, the virus could be viable longer, they noted.
“Based on the accumulated data since the start of the COVID-19 pandemic, the infectious period of SARS-CoV-2 in symptomatic individuals may begin around two days before the onset of symptoms, and persists for about 7-10 days after the onset of symptoms,” the researchers stated.
“Scientifically, I’m very confident that there is enough evidence that the person is no longer infectious after 11 days,” she said.
Singapore's Ministry of Health told The Straits Times it would examine the study carefully to see if it merits a change in policy related to discharging COVID-19 patients.
The Singapore study follows a similar one in South Korea, which found that patients who recovered from COVID-19 but later tested positive didn't pass the virus to others while they were "re-positive."
Scientists from the Korean Centers for Disease Control and Prevention identified 790 people, including 351 family members, who came into contact with nearly 300 of around 450 patients who recovered from the virus, but later tested positive.
Researchers didn't find a single case of anyone becoming infected after coming into contact with the recovered patients who again tested positive.
Researchers in South Korea put forward a theory similar to the Singaporean experts, which is that non-viable virus fragments remain in patients after recovery.
More research is required to determine why patients are re-testing positive for the virus, officials cited in the report said.