World Health Organization Director-General Tedros Adhanom Ghebreyesus speaks during a press conference following an emergency talks over the new SARS-like virus spreading in China and other nations in Geneva on January 22, 2020.

"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 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.

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 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.