BEIJING — China will step up targeted screening of people infected with the novel coronavirus but showing no symptoms, a health official said on April 2.

The surveillance for asymptomatic infections will be expanded to include close contacts of confirmed COVID-19 patients and asymptomatic patients, cluster outbreaks, and key areas and populations with high risk of infections, Wang Bin, with the National Health Commission (NHC), said at a press conference in Beijing.

Medical institutions will, with the help of communities and fever clinics, increase efforts to identify asymptomatic patients and put them under concentrated quarantine in a timely manner, she said.

The Chinese health authority has required nationwide hospitals and disease control departments to take prompt actions once asymptomatic carriers of COVID-19 are detected.

Medical institutions are ordered to report infections to their superior disease control departments within two hours of asymptomatic COVID-19 carriers being found, Wang said.

Meanwhile, an epidemiological survey including a contact investigation should be completed within 24 hours by disease control departments, Wang added.

Once verified, asymptomatic carriers will be put under concentrated medical observation for 14 days and can only be released from quarantine upon two consecutive negative nucleic acid test results, with a sampling interval of more than 24 hours, according to the NHC.

Regarding the infectivity of asymptomatic cases, Wu Zunyou, a senior researcher with the Chinese Center for Disease Control and Prevention, said that local research conducted in Ningbo of East China's Zhejiang province found that the transmission efficiency of asymptomatic cases is about one-third that of confirmed cases.

Noting that there are not enough statistics on the infectious period and infectivity of asymptomatic cases, Wu said more research and observation should be conducted.

With the current epidemic prevention and control measures, the possibility of asymptomatic cases leading to further spreading of the disease is very low, he said.

Since April 1, the NHC has started to incorporate information on asymptomatic cases in its daily report to timely respond to social concerns.

As of the end of April 1, a total of 1,075 asymptomatic patients were under medical observation on the Chinese mainland, including 226 from abroad, according to the NHC.