WUHAN, March 4 (Xinhua) -- The novel coronavirus disease (COVID-19) usually causes less severe symptoms than the SARS virus, but is more easily transmitted, a Chinese expert said Wednesday.

The mortality rate of COVID-19 in Hubei Province, the hardest-hit region, is about 3 percent to 4 percent, and less than 1 percent outside the province, said Cao Bin, a respiratory disease expert, at a press conference, adding that both are lower than that of SARS, which is around 10 percent.

Based on documented cases, COVID-19 is more widely distributed around the world, Cao said.

People infected with novel coronavirus are older than SARS patients in general, said Li Haichao, vice president of Peking University First Hospital.

Some patients may have a very slow onset such as a mild fever for two weeks before a quick exacerbation, Li added.