Dr Michael Ryan, the organisation’s head of emergencies, warned that 90 per cent of the world may still be at risk of catching Covid-19.
Speaking to a meeting of the WHO's 34-member executive board focusing on Covid-19 on Monday, Dr Ryan said the figures vary from urban to rural settings, and between different groups, but that ultimately it means "the vast majority of the world remains at risk."
He said the pandemic would continue to evolve, but that tools exist to suppress transmission and save lives.
“Our current best estimates tell us about 10 per cent of the global population may have been infected by this virus,” he said.
"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.
"We are now heading into a difficult period. The disease continues to spread."
Dr Ryan was flanked by his boss, WHO director-general Tedros Adhanom Ghebreyesus, who minutes earlier led a moment of silence to honour victims as well as round of applause for the health workers who have worked to save them.
Dr Ryan said southeast Asia faced a surge in cases, Europe and the eastern Mediterranean were seeing an increase in deaths, while the situations in Africa and the Western Pacific were "rather more positive."
The WHO estimate would amount to more than 760 million people based on current world population of about 7.6 billion.
It far outstrips the number of confirmed cases as tallied by both the WHO and Johns Hopkins University – with both reporting more than 35 million worldwide.
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, Dr Ryan added.
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