(Yicai Global) April 2 -- China will strengthen its targeted screening of Covid-19 carriers who show no symptoms, expand surveillance to include those who had close contact with confirmed carriers and asymptomatic infections, and actively test those coming from virus-hit regions, according to a top health official.

Regulators will play a monitoring role in the community and in fever clinics, Wang Bin of the National Health Commission's Bureau of Disease Prevention and Control said at a press conference in Beijing today, adding that they will do an effective job of tracking and managing sources of infection to find asymptomatic cases in time and take isolation measures in a timely manner.

Wang promised that the authorities will perform epidemiological checks on asymptomatic cases on time to identify the source and release relevant information in an open and transparent manner.

Wu Zunyou, chief epidemiologist at the Chinese Centers for Disease Control and Prevention, told reporters that according to a study done by a regional CDC the virus transmission efficiency of asymptomatic infected persons is one third of that of confirmed patients. But since just 4.4 percent of infections were spread by asymptomatic infected cases, their contribution to the spread of the Covid-19 pandemic is still relatively minor.

Data on the asymptomatic transmission period, ability and proportion are still very limited, and more research and observation is needed, Wu said.

The National Health Commission has updated data on asymptomatic infections each day since March 31. China reported 55 new cases of such infections yesterday, of which 17 entered from abroad, nine of whom became confirmed cases on the same day. The total number of asymptomatic infections under medical observation is 1,075, 226 of them from overseas, health authorities said.

Editor: Peter Thomas