The novel coronavirus epidemic is experiencing a major slowdown, Zeng Guang, a chief epidemiologist at the Chinese Center for Disease Control and Prevention, said on Wednesday.

However, he warned that a rebound in new infections is likely due to massive population movements amid the nationwide return to work after the extended Spring Festival holiday.

Outside Hubei province, the epicenter of the outbreak, daily confirmed cases had been declining for six days, signifying that the turning point preceding the slowdown occurred around Feb 5, Zeng, also a member of the National Health Commission's senior-level expert panel, said on the Sina Weibo micro-blogging platform.

Due to inevitable delays resulting from the incubation period and diagnostic procedures, he added that the turning point would have occurred earlier, about five to 10 days after Wuhan - Hubei's provincial capital, where the disease first emerged -- went into lockdown on Jan 23.

Zeng said that in epidemiological analysis, a turning point refers to the change from a rising trend of infections to a decreasing one, rather than the final word on an epidemic.

However, he warned that the epidemic will inevitably rebound as an estimated 160 million people return to workplaces following the end of the Spring Festival break, with the Yangtze River Delta, the Pearl River Delta and the Beijing-Tianjin-Hebei region at the highest risk of seeing a surge in infections.

The three regions are densely populated and home to much of the country's key economic activity.

"Whether they ride trains, buses or take planes, the enormous number of people on the way back to work are clustered in enclosed spaces, increasing the risk of virus transmission," he said, adding that "arduous efforts and refined measures" should be implemented to curb the spread of the disease, which the World Health Organization has officially called COVID-19.

Zeng estimated that the rebound could occur about 14 days, or a full incubation period, after the travel peak. Taking into account the time it took for health officials to detect and identify cases, the rebound was likely to be noticed a week later.

"My greatest concern is that because of the data latency, people might lower their guards and overlook the trend that the travel rush will result in a new increase in infections," he said.

"Whether the rebound will occur and at what scale are closely related to the implementation of each area's prevention work. After overcoming this barrier, we will be one step closer to making an objective prediction on the final, decisive end to the battle."