China for the first time publicized a breakdown of people testing positive for the novel coronavirus without outward signs of being sick, revealing that those among them who remain symptom-free throughout infection are in the majority.
Among 6,764 people who tested positive for infection without showing symptoms, only one fifth of them -- 1,297 -- have so far developed symptoms and been re-classified as confirmed cases, China’s National Health Commission spokesman Mi Feng said at a briefing in Beijing Wednesday.
Some 1,023 are still being monitored in medical quarantine to see if they develop symptoms. The rest -- 4,444 -- have been discharged from medical observation after recovering from the virus.
The phenomenon of asymptomatic transmission is a puzzling feature of the virus that’s allowed the pandemic to spread wider and faster than previous outbreaks. While researchers earlier thought that most patients ultimately end up developing symptoms, the indication from China’s data that a sizable group remains symptom-free throughout infection underscores the challenge of containing the widening pandemic.