A doctor reads the CT scan images of 2019-nCoV patients in a hotel accommodating isolated people in Wuhan in central China's Hubei province Monday, Feb. 03, 2020.

"Studies are ongoing because they are checking a number of animal species, so it takes some time," Briand said.

Scientists are running tests on various animals, but have so far not found the host responsible for the outbreak, Dr. Sylvie Briand, head of WHO's Global Infectious Hazard Preparedness division, told reporters at a news conference at the agency's headquarters in Geneva.

The new coronavirus that emerged from a seafood market in Wuhan, China, likely originated in bats and then jumped to an "intermediate host" before infecting humans, World Health Organization officials said Tuesday.

Briand said scientists made the discovery after conducting further studies on the virus's genetic sequence that Chinese health authorities were able to isolate and share on a public database. They found the new virus, which has been named COVID-19, is very similar to other coronavirus found in bats, she said.

But when scientists went to the seafood market in Wuhan, they "didn't find so many bats," Briand said. It "requires more research."

SARS, the coronavirus that emerged in November 2002 and killed nearly 800 people across the world over nine months, was also believed by scientists to have originated in bats before spreading to civet cats and later humans.

Last month, a group of scientists said that snakes, particularly the Chinese krait and the Chinese cobra, may have been the source of the new virus. But officials from WHO later cast doubt on that theory, saying there was "no conclusive evidence."

The discovery comes as the virus has spread to more than a dozen countries and sickened more than 43,000 people — with the number of new cases growing by the thousands every day.

WHO officials said Tuesday that they are worried about the virus mutating.

The coronavirus produces mild cold symptoms in about 80% of patients, Briand told reporters in a press conference Monday. About 15% of the people who contract the virus have ended up with pneumonia, with 3% to 5% of all patients needing intensive care, she said.

The WHO's global research and innovation forum met for the first time Tuesday at the organization's headquarters in Geneva.

Attendees include representatives of China and other member states, infectious disease experts, bioethicists, and major research funders, according to the preliminary agenda.

Dr. Mike Ryan, executive director of WHO's emergencies program, said Monday the team, working with Chinese scientists, hopes to learn the source of the outbreak and the virus's natural host.

Read CNBC's live updates to see the latest news on the COVID-19 outbreak.



