GENEVA (Reuters) - Roughly 1 in 10 people may have been infected with the novel coronavirus, leaving the vast majority of the world’s population vulnerable to the related COVID-19 disease, the World Health Organization (WHO) said on Monday.

Mike Ryan, the WHO’s top emergency expert, told the agency’s Executive Board that outbreaks were surging in parts of southeast Asia and that cases and deaths were on the rise in parts of Europe and the eastern Mediterranean region.

“Our current best estimates tell us about 10% of the global population may have been infected by this virus. It varies depending on country, it varies from urban to rural, it varies depending on groups. But what it does mean is that the vast majority of the world remains at risk,” Ryan said. “We are now heading into a difficult period. The disease continues to spread.”

The WHO has submitted a list of experts to take part in an international mission to China to investigate the origin of coronavirus, for consideration by Chinese authorities, he said.