"I never said no human-to-human transmission in the public," Gao Fu, director of the Chinese Center for Disease Control and Prevention (China CDC), said in an interview with CGTN, responding to accusations of him not being honest about the epidemic situation during the beginning of the outbreak.

China confirmed human-to-human transmission of the novel coronavirus on January 20. Before that, official reports claimed that there was possibility of limited human-to-human transmission but no clear evidence, which raised the public's concerns regarding the transparency of China CDC.

Most people in the country received the information that the virus could be transmitted between humans from a CCTV interview with China's top respiratory expert Zhong Nanshan on January 21.

Gao told CGTN that no scientist could say that there was no human-to-human transmission because no one was familiar with the new virus at the beginning.

"This is a virus from its (coronavirus) family, there is always human-to-human transmission," he said, stressing that the most important thing is to find facts and make judgments using evidence.

Gao, who is also a member of the high-level expert group of the National Health Commission, arrived in the epicenter Wuhan with other five members including Zhong on January 18.

In a meeting on January 19, the experts discussed the possibility of human to human transmission of the novel coronavirus. 

"The problem is the seriousness… we realized it is a very efficient human-to-human transmission," he said. 

The group found some clear cluster cases after field research in Wuhan, and then confirmed the fact of transmission between people.

In a press conference in the evening of January 19, the high-level expert group released the results of their research that the virus has finished its "jump" from animal to human, and developed to "limited human to human transmission".

The next day, the experts told the public that the virus had entered the stage of "efficient human to human transmission," Gao said.