New CDC report finds COVID-19 can be spread 1-3 days before onset of symptoms

A new report from the Centers for Disease Control and Prevention on Wednesday provides new evidence to bolster early reports that the transmission of the coronavirus — which has now infected over 887,000 people worldwide — can happen prior to symptoms. Published in the CDC’s Morbidity and Mortality Weekly Report (MMWR), the study underscores the potential difficulty of containing a virus that may be spreading silently.

The report focused on the transmission of COVID-19 from Jan. 23 to March 16 in Singapore — specifically, seven “clusters” in which presymptomatic transmission occurred. Presymptomatic transmission is defined by the researchers as “the transmission of SARS-CoV-2 from an infected person (source patient) to a secondary patient before the source patient developed symptoms.”

Of the 243 cases recorded in Singapore by the end of the study, 157 were transmitted locally (meaning they were not brought in from travelers), and of those, at least 10 of the cases were connected to presymptomatic transmission. “The evidence of presymptomatic transmission in Singapore, in combination with evidence from other studies supports the likelihood that viral shedding can occur in the absence of symptoms and before symptom onset,” the authors write.

Although it remains unclear exactly how long individuals may be carrying the virus before symptoms appear, the researchers found that exposure “occurred 1–3 days before the source patient developed symptoms.” At least two of the cases occurred from individuals who acquired the virus during a singing practice, another occurred between two housemates.

https://www.yahoo.com/lifestyle/new-cdc-report-finds-covid-19-can-be-spread-13-days-before-onset-of-symptoms-174344709.html