The World Health Organization has declared the coronavirus outbreak that has spread from China to 18 other countries a global health emergency.
Thursday’s announcement from Geneva means the WHO regards the outbreak as an "extraordinary event" needing a coordinated international response.
Experts say there is evidence of people-to-people transmission of the virus.
The Centers for Disease Control Thursday reported the first case of human transmission in the United States. Doctors say a Chicago man caught the virus from his wife who had been in Wuhan. He is the sixth confirmed coronavirus case in the United States.
India and the Philippines announced their first confirmed cases Thursday, joining a growing list that includes Australia, Canada, Finland, France, Germany, Hong Kong Japan, Nepal, Singapore, South Korea, Thailand, the United Arab Emirates, and Vietnam.
China says as of Thursday, there are 7,800 cases in China and 170 deaths.
The United States has evacuated more than 200 people from Wuhan. Several other countries have also evacuated their nationals and some international airlines have suspended direct flights to China.
U.S. President Donald Trump was briefed on the outbreak by those he calls the "great agencies" working with China.
"We will continue to monitor the ongoing developments. We have the best experts anywhere in the world and they are on top of it 24/7," he tweeted late Wednesday.
The White House has said it is considering further restrictions on U.S. airlines flying to China, in addition to the voluntary restrictions by some air carriers. It has not yet decided whether to impose a travel ban.
The U.S. Centers for Disease Control and Prevention said none of the 195 American passengers evacuated Wednesday from Wuhan show symptoms of coronavirus. They will remain at a U.S. military base in California at least through the end of the week.
The CDC said the risk to Americans is low and that it is working with the WHO to get a U.S. team to China as soon as possible.
The CDC's Dr. Nancy Messonnier says the symptoms of a cold or the flu and the coronavirus are the same, but the risk factors are having visited China's Hubei province or having close contact with those who have been there.