BBC Health and Science Correspondent James Gallagher says they have a crucial new piece of information, people with no symptoms of infection may be able to spread the virus.
Scientists in China have published detailed information, in the Lancet medical journal, on the first cases in the country.
It includes information on a child with no outward symptoms, but a clear coronavirus infection in their lungs.
Prof Kwok-Yung Yuen from the University of Hong Kong-Shenzhen Hospital said "asymptomatic infection appears possible".
How often or easily this happens is far from clear, but it could make the virus far harder to contain.
Prof Yuen says if this was the case, then controlling the epidemic would rely on isolating patients and quarantining anyone they came into contact with "as early as possible".
Researchers also said the new virus was closely related to one found in Chinese horseshoe bats.