The ongoing coronavirus outbreak is a global health emergency, the World Health Organization determined today. Since it started last month, the virus’s spread has reached nearly two dozen countries, sickened thousands, and impacted both travel and business around the world.

“The main reason is not because of what is happening in China, but because of what is happening in other countries,” said Tedros Adhanom, director general of the WHO, in a press conference today. “Our greatest concern is the potential for the virus to spread to other countries with weaker health systems, which are ill prepared to deal with it.”

The WHO defines a global emergency — formally, a Public Health Emergency of International Concern — as “an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response.” This is the sixth declared in the past decade.

Despite the emergency declaration, the WHO is not recommending any restrictions on travel or trade at this time. Countries should implement evidence-based public health policies, combat misinformation, share data, and work together to stop the spread of the virus, Adhanom said. The WHO also called for an acceleration in efforts to develop vaccines and treatments, and stressed that support be given to countries with weak health systems which might not be able to cope with the virus.

The International Health Regulations Committee at the WHO is tasked with examining the evidence around an ongoing public health crisis and recommending that an emergency be declared. The committee met twice last week, and both times were split fifty-fifty on whether to recommend an emergency declaration. At that time, committee members who did not want to declare a global emergency said there weren’t enough cases outside of China to warrant it.

The committee has now decided to recommend that an emergency be declared because of an increased number of cases, an increased number of countries affected, and news of “questionable” measures taken against travelers in some countries, said committee chair Didier Houssin during the press conference.

Declaring a global health emergency gives the director general of the WHO the power to offer recommendations that could prevent the spread of a disease, like travel advisories or restrictions, and allow them to review public health measures in place in affected countries. The recommendations are just recommendations, but there’s pressure on countries to follow them.