Expert: Asymptomatic cases won't lead to large-scale virus spread

Asymptomatic novel coronavirus patients will not be able to result in large-scale transmission of the epidemic, said a senior expert on Thursday. 

Wu Zunyou, chief researcher with the Chinese Center for Disease Control and Prevention, said these people are actually in the incubation period and two-thirds of them will exhibit symptoms and become confirmed cases. 

"All the asymptomatic patients must have had contact with confirmed cases or traveled to areas with the epidemic," he told a news conference in Beijing. 

Current epidemic prevention and control measures in China could help find and isolate such people in a timely manner, he added. 

Quoting recent two studies, he warned that the ability of these people to spread the disease may be exaggerated without adequate and thorough investigation and analysis.  

A study by the disease control and prevention center of Ningbo, Zhejiang province, found that confirmed cases could infect almost three people on average, while asymptomatic cases could infect almost one on average. 

The research also found that the number of confirmed cases infected by asymptomatic patients accounts for 4.4 percent of total infections. 

In another study on a larger scale in a province in South China, researchers found that only seven people out of 1,500 close contacts with asymptomatic cases had developed the disease. 

Further investigation found, however, the seven people had contact with not only asymptomatic cases but also other confirmed patients, he said.  

"Some people may be exposed to both confirmed cases and asymptomatic cases. If investigations are not done thoroughly, the findings may not be valid and could exaggerate the ability of asymptomatic cases to spread the virus," he said. 

Current available data has yet to be big enough to judge these people's capability in spreading the pathogen. "More research and observations are still needed," he said.