The death toll from the coronavirus outbreak has risen to 170, and a confirmed case in Tibet means it has reached every region in mainland China.
Chinese health authorities said there were 7,711 confirmed cases in the country as of 29 January.
Infections have also spread to at least 15 other countries.
The World Health Organization (WHO) will meet on Thursday to again consider whether the virus constitutes a global health emergency.
“In the last few days the progress of the virus, especially in some countries, especially human-to-human transmission, worries us,” WHO Director-General Tedros Adhanom Ghebreyesus said on Wednesday.
He named Germany, Vietnam and Japan, where there have been cases of people catching the virus from others who have been to China.
“Although the numbers outside China are still relatively small, they hold the potential for a much larger outbreak,” the WHO chief said.
More people have now been infected in China than during the Sars outbreak in the early 2000s, but the death toll remains far lower. Sars, also a coronavirus, caused acute respiratory illness.
Researchers are racing to develop a vaccine to protect people from the virus. One lab in California has plans for a potential vaccine to enter human trials by June or July.