The World Health Organisation on Thursday declared the coronavirus epidemic an international public health emergency, as another 38 patients were announced to have died.
The designation is rarely used and could lead to improved international co-ordination in tackling the disease.
"Our greatest concern is the potential for the virus to spread to countries with weaker health systems," WHO chief Tedros Adhanom Ghebreyesus told a briefing in Geneva.
"This is not a vote of no confidence in China."
China said on Thursday that the number of deaths from coronavirus had risen to 170, with cases confirmed in every province and region in the country.
More than 7,700 people have fallen sick in mainland China, with another 68 cases reported around the world.
The WHO met on Thursday to decide whether to declare an emergency, having convened twice last week when it decided it did not have enough information to make the call.