The spread of a fast-moving virus outside of China is of "grave concern" and has prompted the World Health Organization to reconvene an emergency meeting this week to decide whether it's become a global health emergency, WHO officials said Wednesday.
The coronavirus has spread to a handful of people through human-to-human contact outside of China, Dr. Mike Ryan, executive director of the WHO's health emergencies program, said at a news conference at the organization's Geneva headquarters Wednesday.
"These developments in terms of the evolution of the outbreak and further development of transmission, these are of grave concern and has spurred countries into action," Ryan said, adding that he just returned from China on Wednesday. "What we know at this stage, this is still obviously a very active outbreak and information is being updated and changing by the hour."
The coronavirus outbreak has killed 132 people in China and sickened more than 6,150 across more than a dozen countries across the globe. Ryan said there are currently 71 cases outside of China in 15 other countries.
The WHO declined at two emergency meetings last week to declare the virus a global health emergency.
Since the first patient was identified in Wuhan on Dec. 31, the number of coronavirus cases has mushroomed to 6,061 in mainland China as of Wednesday morning, exceeding the total number of SARS cases in that country during the 2003 epidemic. There were 5,327 SARS cases in China and 8,000 across the world diagnosed between Nov. 1, 2002, and July 31, 2003, according to the WHO.
One of the criteria used to determine whether the coronavirus is an international health threat is whether the disease spreads locally once it arrives in new parts of the world, "and that's a nuanced and important distinction to make," Ryan told reporters last week.
The other main criteria is whether it's already interfered or will likely interfere with trade and travel, he said. The WHO committee's goal, he said, is to contain an outbreak without needlessly disrupting economic activity just by declaring a global health crisis.
German health officials Tuesday said that a 33-year-old man there contracted the virus from a colleague visiting his workplace from Shanghai, confirming what appears to be one of the first cases of person-to-person transmission outside China.
WHO Director-General Tedros Adhanom Ghebreyesus said the "continued increase in cases and the evidence of human-to-human transmission outside of China are, of course, most deeply disturbing." The illness produces a range of symptoms with about 20% of the patients becoming severely ill, including pneumonia and respiratory failure, he said.
"Although the numbers outside China are still relatively small, they hold the potential for a much larger outbreak," Tedros said.
Tedros, who joined the news conference late, said he met with Chinese leader Xi Jinping, China's National Health Commission minister, Ma Xiaowei, and China's minister of foreign affairs, Wang Yi, on Tuesday. During the visit, Tedros and Chinese leaders discussed containment measures and sharing data on the virus, he said.
"I was very encouraged and impressed by the president's knowledge of the outbreak and his personal involvement in the response," Tedros said.
WHO officials said they view the outbreak on four fronts: The public health response in Wuhan, the response in other provinces in China, the 15 other countries with reported cases and preventative measures by the whole world.
"We're continuing to share information, guidelines and tools," Ryan said.
READ MORE: Today's live coronavirus updates are here.
— CNBC's William Feuer contributed to this report.