Gene-sequencing of 104 novel coronavirus samples collected from different locations shows the virus has not mutated, a top Chinese expert told a news conference on Monday.

Liang Wannian, head of the Chinese expert panel on outbreak response and disposal, said that the genetic data of the samples were 99 percent homogeneous, signs that mutation hasn't occurred.

He shared what is known so far about the deadly pathogen at a news conference held by the WHO-China Joint Mission on COVID-19 in Beijing. The findings are based on the Chinese government's data and a field study in Central China's Hubei, South China's Guangdong and Southwest China's Sichuan provinces by the joint expert team, he said.

According to the findings, the average age of confirmed patients is 51, with 77.8 percent aged between 30 and 69, and 77.5 percent of the cases in Hubei province - the center of the outbreak.

The bat is likely the host, and the pangolin is possibly one of the intermediary hosts, he said.

Liang said the coronavirus is mainly transmitted through respiratory droplets and physical contact, and there's a risk for fecal-oral and aerosol transmission. But he noted that fecal-oral and aerosol transmission are not major transmission routes in the Chinese mainland.

Data from Guangdong and Sichuan provinces showed 78 to 85 percent of patients got infected within families, which shows that control measures have been effective in halting the virus from spreading within communities, he said, adding that 1 to 5 percent of the close contacts of infected patients tested positive for the virus in the two provinces.

He said since it is a new virus, people of all age groups lack immunity. It takes roughly two weeks for patients with mild symptoms to recover, and up to six weeks for critically ill patients to recover.