“You would need to keep on these control measures to varying degrees until one of two things happen: One, is there is natural immunity by active infection and recovery, or there is sufficiently wide availability of an effective vaccine administered to at least half the population, to create the same effective herd immunity. These are the only two ways of going about it.” Leung added that we’ll go through “several cycles” of tightenings and easings “before we will have resolution.”

Leung was alerted to the new coronavirus by contacts in mainland China on December 31

Since he became involved in the response, Leung said his experience working with Chinese counterparts has been positive. During the WHO trip, Chinese officials were “very open, very transparent, a whole of government approach,” he told me. “Wherever we went, we were asking difficult questions and we were asking for the data, to look at the data and to discuss with their scientists, and they've been nothing but forthcoming.”

“China bought the rest of the world time,” Leung said.