(Yicai Global) April 2 -- With the novel coronavirus outbreak under control in China, normal daily life has resumed in many places. But a county in Henan, the most populous province in central China, has again imposed a lockdown due to the detection of many asymptomatic Covid-19 cases.

Notices issued by the body in Ji county overseeing efforts to combat the coronavirus outbreak have circulated online, ordering comprehensive lockdown measures. They include keeping just one entrance and exit for all local communities and villages, allowing special pass holders to enter and exit these areas, suspending non-essential businesses, as well as stopping work and production at some firms.

Yicai Global confirmed the authenticity of these notices with authorities in the county. An unnamed official said that the measures were related to several cases of Covid-19 infections in people not showing symptoms found in recent days, including a pediatrician who had been in contact with many patients and their families before testing positive.

Henan reported a local confirmed case and three asymptomatic cases on March 29, after 30 straight days of no new confirmed cases. The three asymptomatic infections were from Jia county and the confirmed Covid-19 patient, who had close contact with one of the asymptomatic patients, was from Luohe city.

The cases triggered public concern about asymptomatic contagion, prompting the National Health Commission to publish data on such infections every day since March 31. Today's data release showed that there were 55 new cases of asymptomatic infections nationwide yesterday, of which 17 came from abroad. A total of 1,075 asymptomatic patients are undergoing medical observation, 226 of whom were so-called imported cases.

Studies show that the virus transmission efficiency of asymptomatic patients is about one-third of that of confirmed cases so they contribute little to the spread of the epidemic, Wu Zunyou, chief epidemiologist of the Chinese Center for Disease Control and Prevention, told a press briefing today.

Editors: Dou Shicong, Peter Thomas