Despite extensive study by doctors and scientists across the world since the new coronavirus first appeared in China three months ago, much about the scourge is still unclear. One of the biggest mysteries is why the virus produces few or no symptoms in around 80 percent of people, according to the World Health Organization, yet in others it can lead to fatal pneumonia. During the peak of the epidemic in China, he and a team from the University of Nanchang compared those with mild and severe forms of the illness.
