China has begun a major survey to determine how many people might have been infected with the coronavirus and then recovered without ever showing symptoms , while also assessing immunity levels within different communities, state media reported. The research will be conducted in six provinces, including Hubei which was the focus of the initial outbreak, as well as Beijing, Shanghai and Chongqing. Wuhan , the capital of Hubei and home to about 60 per cent of all infections reported in mainland China, is taking the lead in the study, which involves giving both nucleic acid and antibody tests to 11,000 of its 11 million residents, state news agency Xinhua reported on Wednesday. Health workers collected throat swabs and blood samples from about 900 people randomly selected from eight subdistricts of the city on Tuesday, Ding Gangqiang, head of the Wuhan epidemiological survey team, was quoted as saying. “The purpose is to learn about the immunity level in communities and provide scientific support on how we should adjust our disease control strategies,” he said. Professor Lu Hongzhou, a specialist in infectious diseases who heads the Shanghai Public Health Clinical Centre where Covid-19 patients are being treated, said he supported the research though the collection of samples had yet to start in the city. “We haven’t received notification from the top [to start],” he said. “The number of infections [in Shanghai] is not very big, but I think we’d better do this so as to have an idea of the scale of asymptomatic carriers.” Professor Jin Dong-yan, a molecular virologist at the Li Ka Shing Faculty of Medicine at the University of Hong Kong, said that the use of both nucleic acid and antibody tests would enable scientists to determine those people who had been infected but recovered without medical aid and without showing symptoms. If a person tested positive in a nucleic acid test, it meant they were carrying the virus, and if positive in an antibodies test, it meant that they had contracted the virus and had recovered, he told the South China Morning Post . “This is very important as it will help us to direct our countermeasures in the future,” Jin said. “If we find, say 60 per cent, of the population has acquired immunity, then lockdowns will no longer be meaningful. If it turns out that there are many people with a high viral load but without symptoms, then we should be on high alert and take stricter measures. “For people in Hubei, the tests can also save them from discrimination when they get back to work – those who prove to have developed immunity are very unlikely to get infected [again] for at least a year,” he said. Wuhan hotel owners say they’re on the brink of going bust Beijing began adding asymptomatic cases to the nation’s daily infections tally at the start of April amid concerns that such people could trigger a second outbreak once the widespread lockdowns in cities like Wuhan and elsewhere were lifted. China reported 103 new coronavirus infections on Wednesday, of which 39 were imported. Of the total, 57 people had no symptoms, including three of the imported cases. Since the outbreak began, China has reported 82,295 cases, of which 95 per cent have recovered and been discharged from hospital.