COVID-19 patients might not be contagious 11 days after becoming ill, according to a study cited by the Singapore National Center for Infectious Diseases and the Academy of Medicine.
“Scientifically, I’m very confident that there is enough evidence that the person is no longer infectious after 11 days,” NCID executive director Leo Yee Sin told Singaporean newspaper the Strait Times.
The study showed a patient can test positive for the virus on Day 12, but “viral RNA detection by PCR does not equate to infectiousness or viable virus” as COVID-19 “could not be isolated or cultured after day 11 of illness,” according to researchers. PCR means polymerase chain reaction and is a method to read small samples.
“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 2 days before the onset of symptoms, and persists for about 7-10 days after the onset of symptoms,” the study concluded. “Active viral replication drops quickly after the first week, and viable virus was not found after the second week of illness despite the persistence of PCR detection of RNA. These findings are supported by epidemiologic, microbiologic and clinical data.”
The findings can help hospitals on releasing COVID-19 patients and lead public testing policy, according to the study.
“These new findings allow for revised discharge criteria based on the data on the time course of infectiousness rather than the absence of RNA detection by PCR testing, taking into consideration both the clinical and public health perspectives, including the individual patient’s physical and mental well-being,” the study’s conclusion continued. “In addition, given these findings, resources can focus on testing persons with acute respiratory symptoms and suspected COVID-19 in early presentation, allowing timelier public health intervention and containment.”