Roughly 10 per cent of the world's population may have been infected with the Coronavirus, leaving the vast majority vulnerable to the COVID-19 disease, the World Health Organization has said.

"Our current best estimates tell us about 10 per cent of the global population may have been infected by this virus. It varies depending on the 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," Mike Ryan, the WHO's top emergency expert said on Monday.

The world, he said, is now heading into a difficult period as the disease continues to spread. He noted the surge of cases in parts of Southern Asia, and the rise of deaths across Europe, and the eastern Mediterranean region is cause for concern, a report of the World Economic Forum said.

Ryan was addressing WHO's executive board, where the United States took a dig at China for its "failure" to provide accurate and timely information on the outbreak.

The WHO has submitted a list of experts to take part in an international mission to China to investigate the origin, for consideration by Chinese authorities, Ryan said, without giving details.

US assistant health secretary Brett Giroir said that it was critical that WHO's 194 member states receive "regular and timely updates, including the terms of reference for this panel or for any field missions so that we can all engage with the process and be confident in the outcomes".

Germany, speaking for the EU, said the expert mission should be deployed soon, with Australia also supporting a swift investigation.

Meanwhile, Alexandra Dronova, Russia's deputy health minister, called for an evaluation of the legal and financial repercussions of the Trump administration announcing the US withdrawal from the WHO next July, the WEF reported. The United States has decided to not pay around $80 million it owes the WHO, the WEF said.