Scientist: Search for China's patient zero challenging

China is still looking for its COVID-19 patient zero, which is a challenging task, medical experts and scientists said on Monday.

Finding patient zero is something that many countries are doing. But it is a very challenging task as it involves very complex data and needs time, said Liu Peipei, a researcher with the National Institute for Viral Disease Control and Prevention of the Chinese Center for Disease Control and Prevention.

"It's very difficult to give a very clear conclusion about individuals' infection periods," Liu said at a news briefing held by the State Council Information Office.

Finding patient zero is important for tracing the source of the virus and preventing a new virus from spreading in the future, Wang Guiqiang, director of the Infectious Disease Department at Peking University First Hospital, said at the news briefing.

But it is a very difficult scientific process, according to Jin Qi, head of the Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College.

"Till today, no one can say for sure that we've found patient zero in the H1N1 influenza in the United States in 2009," he said. "If a person is asymptomatic or only has mild symptoms and hasn't gone to a doctor, it's impossible for us to determine whether the case is patient zero because there is no medical record to track."