COVID-19 viral spreading may occur 2 to 3 days prior to first symptoms: study

(ECNS) -- The latest research by a team at the University of Hong Kong shows viral shedding in a novel coronavirus patient might commence two to three days before the appearance of symptoms.

The researchers observed 94 patients with laboratory-confirmed COVID-19, who were admitted to Guangzhou Eighth People’s Hospital, modeled COVID-19 infectiousness profiles from a separate sample of 77 infector–infectee transmission pairs and found the highest viral load in throat swabs at the time of symptom onset.

They estimated viral shedding in patients with laboratory-confirmed COVID-19 peaked on or before symptom onset, and a substantial proportion of transmission probably occurred before first symptoms in the index case.

But the research team also admitted their study has several limitations, saying that the effectiveness of control measures depends on several key factors, including the serial interval (duration between symptom onset of successive cases in a transmission chain) and the incubation period (time between infection and onset of symptoms). 

More inclusive criteria for contact tracing to capture potential transmission events two to three days before symptom onset should be considered for effective control of the outbreak, they suggested.

Their research result was released on the journal Nature Medicine.