Society

Testing the Masses

Wuhan decided to test all 11 million of its residents for the coronavirus, at great expense. Experts advise that precise testing and a long-term epidemic prevention system could be more effective

By Li Mingzi , Du Wei Updated Aug.1

On the afternoon of May 16, 2020, Li Hang (pseudonym), a doctor at a hospital in Jiang’an District in Wuhan, Hubei Province and his colleague went to a community medical service center to help conduct coronavirus testing of 400 residents.　

Since May 14, Wuhan, center of the first mass outbreak of Covid-19, which has a population of 11 million, launched citywide mass testing to identify asymptomatic patients of coronavirus - those carrying the virus but who show no obvious symptoms. It was an action authorities referred to as the “10-day battle” to prevent a second wave of infections. According to local newspaper the Changjiang Daily, more than nine million people had been tested as of May 24 and 227 asymptomatic patients were found.　

Jiang Qingwu, former head of Fudan University’s School of Public Health in Shanghai, told NewsChina that even though only a few asymptomatic patients were identified, there are still contagious virus carriers and it was not time to relax the nation’s vigilance.　

Huge Endeavor

Wuhan health authorities organized staggered times for testing across residential communities to prevent cross infection. Both permanent and temporary residents who had not tested positive for Covid-19 could be tested, with priority given to residents in communities where confirmed cases were reported, as well as those living in older and densely-populated residential buildings. Children under six were not encouraged to be tested. In addition, all tests were conducted in designated outdoor public spaces. Health workers also paid door-to-door visits to some elderly and disabled residents.　

Li Hang told our reporter that in a few residential communities, some people were reluctant to be tested for fear of cross-infection. 　

Many medical personnel in the city were involved in the endeavor. According to a doctor at Wuhan Red Cross Hospital who spoke on condition of anonymity, his hospital sent 20 medical teams each with more than 100 staff to many residential communities in Jianghan District and more than 10,000 swab test samples were conducted a day. A doctor from Zhongnan Hospital of Wuhan University told our reporter that his hospital also sent more than 200 nurses to nearby communities to collect more than 10,000 samples each day.　

In Qiaokou District’s Liujiao residential community, around 1,000 people were tested on May 13. “Residents in our community were very supportive. Our aim was to leave no one untested,” Wang Kaiqi, the community’s Party chief, told Hubei Television.　

After the samples are collected, they are sent to medical institutions and third-party organizations for testing. According to a report by Health News, Wuhan’s nucleic acid testing capacity is 100,000 samples per day. To accelerate mass testing, Wuhan Health Commission designed a new testing method to combine five to 10 individual samples together to test at one time, a method known as pool testing. If a mixture of samples is positive, further tests are conducted for each person in the group.　

Jiang Qingwu said that pool testing has been used for a long time and theoretically, the method will not affect the sensitivity and accuracy of the results, but this depends on the number of individual samples before they are mixed. It is not a foolproof way to identify asymptomatic spreaders. 　

“If the result of the combined test is positive, it is possible that no individual positive sample is found after extra testing because of the detection reagents and operation methods,” he said. “It could mean they have to start all over again.”　

Lan Ke, director of the State Key Laboratory of Virology, Wuhan University, told NewsChina that because of the sensitivity of testing methods and the specificity of samples, as well as the latent period of the virus, nucleic acid testing is able to detect many asymptomatic patients, but it is not always reliable.　

According to statistics from Wuhan Health Commission, from May 14 to 18, 1.2 million tests were conducted and 58 asymptomatic patients were found. From May 19 to 23, 5.36 million tests were conducted and 131 asymptomatic patients were found. Lan argued that alongside the increasingly wider scope of detection, the positive rate of testing dropped from 0.47/10,000 to 0.24/10,000. “It showed that the virus transmissibility has gone down,” he said. “The virulence may have weakened as well.”　

Antibody Tests

Prior to the city-wide testing program, Wuhan launched an epidemiological investigation into where people had developed antibodies for the coronavirus, known officially as SARS-CoV-2, in order to screen for asymptomatic patients. Starting from April 14, 2020, Wuhan conducted 11,000 random serum antibody tests on people who were never diagnosed with Covid-19 in 100 residential communities in 13 administrative districts across the city.　

On April 20, Ding Gangqiang, head of the epidemiological survey team dispatched to Wuhan by the Chinese Center for Disease Control and Prevention (China CDC), told NewsChina that the antibody sample collections had been completed, and they would be analyzed and released by Wuhan CDC officials. To date, however, the final report is yet to be released.　

On May 19, 2020, Feng Zijian, a deputy director of the China CDC, told our reporter that “I am unable to publicize the data now because it is not the appropriate time.” According to a report by financial magazine Caixin, 5 to 6 percent of samples had antibodies against Covid-19. 　

Jiang Qingwu said that as Wuhan is home to 11 million people, if 5 to 6 percent of samples were antibody positive, roughly half a million in the city were infected by Covid-19. It means that besides the 50,000 confirmed cases in Wuhan, 90 percent of virus carriers were not discovered.　

“These confirmed cases are highly likely to be asymptomatic patients who have already recovered after their immune system defeated the virus,” he said, adding that the 5 to 6 percent positive rate is much lower than the 20 percent rate in Western countries. In other words, he said, Wuhan has not achieved herd immunity since the outbreak.　

“If there’s a second wave of the coronavirus, Wuhan is as susceptible to the disease as other cities in the country,” he said.　

Medical workers conduct nucleic acid testing for staff at a factory in Caidian Economic Development Zone in Wuhan, Hubei Province, May 15, 2020

Prevention

A nucleic acid test costs around 180 yuan (US$25) in Wuhan and the citywide testing cost over 1 billion yuan (US$141m). According to the Wuhan Health Commission, the cost was absorbed by the city and district financial budgets.　

Feng Zijian told our reporter that Wuhan launched the mass nucleic acid testing in May because the city had the capability. Before the strictest lockdown measures were lifted on April 4, the coronavirus spread had largely been stopped. The city was under siege for almost three months to contain the spread of the disease. To date, Wuhan has over 50,000 confirmed cases, accounting for more than half of the total number in China. Among the 4,640 reported Covid-19 deaths in the country, about 80 percent were in Wuhan.　

Alongside the discovery of positive carriers, particularly asymptomatic ones, mass testing was put on the agenda. “There are different tasks and concerns according to how the situation changes,” he said.　

Jiang Qingwu told our reporter that if mass testing is necessary, it would have been better to do it before the lockdown was lifted because it would have allowed for work to resume. He argued that nucleic acid testing and epidemic prevention should be conducted more scientifically. “In comparison with mass testing, it is more effective to focus on vulnerable groups and residential communities that are more susceptible to the virus,” he said. 　

Vulnerable groups include medical workers, people in close contact with confirmed cases, and people who live in communities where confirmed cases were reported, he said.　

In early May, imported cases from Wuhan were found in eastern China’s Jinhua, Zhejiang Province and Xiamen in Fujian Province. In the opinion of Jiang Qingwu, there is plenty of room for Wuhan to improve its inspection of vulnerable groups and communities susceptible to the virus.　

Lan Ke said that the mass testing is significant in boosting the confidence of local residents, but in the long run, there should be more precise anti-epidemic and prevention measures. It will be a tremendous financial burden to conduct a second round of mass testing if there is a resurgence of cases in Wuhan.　

“The coronavirus isn’t likely to just disappear like SARS. It’s possible the virus will stay with human beings for a long time,” he said. “As a result, a long-term plan alongside a precise and normalized epidemic prevention system is necessary.”

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Testing the Masses