(Kathleen Doheny/ WedMD) — We’ve been told to avoid people who are obviously sick, coughing, and sneezing to prevent us from getting the new coronavirus.
But up to 25% of people infected may never have symptoms. And in others, their symptoms may not show up until 48 hours after being infected, according to new evidence. Yet researchers have said people in both groups may be “silent spreaders” of the virus.
Several recent studies have backed this up. One that studied transmission in Singapore and China found infection was transmitted between 2.55 and 2.89 days, respectively, before symptoms started.
Another that identified seven clusters of COVID-19 cases in which transmission likely occurred before symptoms found that 6.4% of cases were attributed to transmission before there were symptoms. Another study in China found that 12.6% of the transmissions could have occurred before symptoms began in the “source” patient.
“The initial epidemiologic [research] suggests that asymptomatic spreading is happening,” says Timothy Schacker, MD, a vice dean for research and professor of medicine at the University of Minnesota Medical School. (…)