WHO Director-General Tedros Adhanom Ghebreyesus did not name specific countries but said the list is long. While the majority of COVID-19 cases are still in a handful of countries, Tedros said the WHO is deeply concerned about the increasing number of countries reporting cases, especially those with weaker health systems.

He reiterated that the epidemic is a threat for every country, rich and poor, adding that "even high-income countries should expect surprises.

"The solution is aggressive preparedness," he continued. "We're concerned that some countries have either not taken this seriously enough, or have decided there's nothing they can do."

Rich European countries are not immune to the epidemic. Italy remains the European country hardest hit, with more than 3,000 cases and 107 deaths. On Thursday, France's Health Ministry reported two more deaths, taking the total to six, with 92 new confirmed cases taking the national total to 377, and the United Kingdom also reported its first death, as the number of positive cases rose to 115, 25 of which are in London.

By Thursday morning the Brussels Times reported 27 new cases in Belgium, bringing the total number of people infected to 50.

Tedros pointed out that in some countries, the level of political commitment and action taken did not match the level of threat the world faces.

He warned that it is not a drill, not the time to give up, not a time for excuses. "This is a time for pulling out all the stops," he said.

He said these are plans that start from the top, with leadership coordinating every part of government, not just the health ministry – security, diplomacy, finance, commerce, transport, trade, information, and more – the whole government should be involved.

"Activate your emergency plans through that whole-government approach," he said.

Tedros said that if countries act aggressively to find, isolate and treat cases, and to trace every contact, they can change the trajectory of this epidemic.

"If we take the approach that there's nothing we can do, that will quickly become a self-fulfilling prophecy," he said.

He emphasized that how deadly the virus will be depends not only on the virus itself, but on how people respond to it. "This is a serious disease. It is not deadly to most people, but it can kill," Tedros said.

Michael Ryan, executive director of the WHO's health emergencies program, agreed, saying that some countries have demonstrated that it is possible to control the spread of the virus and slow it down.

He explained that in that calculation, people have two chances to save lives. If you contain and suppress the virus, you save lives by making sure that vulnerable people are not exposed. And if they are exposed, you have more time to get your system ready to save the lives.

"You get another shot at live-saving interventions," Ryan said.