Person-to-person transmission of COVID-19, the disease caused by the novel coronavirus, is unlikely starting 11 days after infection, even if the patient is still testing positive, according to a new study from Singapore, the English-language Singaporean daily the Straits Times reported.
The joint research paper – published by researchers from Singapore’s National Centre for Infectious Diseases (NCID) and the Academy of Medicine, Singapore, and based on a study of 73 COVID-19 patients – explained that a positive test “does not equate to infectiousness or viable virus,” adding that isolating or culturing the virus after 11 days was not possible.
Singapore’s Health Ministry will evaluate the implication of these latest findings, which could cause changes in current discharge policies of patients who tested positive for COVID-19, according to the newspaper.
“We will closely study the position statement and evaluate how we can incorporate the latest evidence… into our patient clinical management plan,” the ministry said in a statement.
In addition, the paper also mentions a “small but important study” involving nine patients in Germany who saw a high amount of viral shedding in their throats and lungs throughout the first week, but saw no viral shedding from day eight and onward.
NCID executive director Leo Yee Sin explained to the Straits Times why their study took three days longer than the German study, explaining that his researchers were “very conservative and counted till the very last drop.”
But while the Health Ministry has yet to rule on it, the researchers behind the study are very confident in its validity.
“Scientifically, I’m very confident that there is enough evidence that the person is no longer infectious after 11 days,” Yee Sin said, according to the Straits Times.
“Studies are still going on and we will get more data, but we will see the same thing as there is a great deal of science in this. So there is no need to wait,” explained Dr. Asok Kurup, chair of the Academy of Medicine’s Infectious Diseases Chapter, the Straits Times reported.
However, it is possible that patients with weakened immune systems, such as cancer patients on chemotherapy, untreated AIDS patients or those taking immuno-suppresant drugs following a transplant, could remain infectious for a longer period, Yee Sin added.
Currently, the discharge criteria in the city-state is based on testing negative for the virus in two tests with 24 hours between them. At the time of writing, about 45% of Singapore’s 31,068 COVID-19 cases have been discharged from hospitals.