The WHO estimated on Monday that 10 per cent of the world had been infected by coronavirus – way more than the official numbers – as it mulled speeding up internal reforms.
To date, more than 35 million cases of Covid-19 have been registered worldwide, including about 1.04 million who have died, according to an Agence France-Presse tally based on official sources.
But the World Health Organisation now estimates that about one in 10 of the planet's 7.8 billion or so people have already been infected since the virus first surfaced in China late last year – more than 20 times the official count.
"Our current best estimate tells us that about 10 per cent of the global population may have been infected by this virus," WHO emergencies director Michael Ryan told a meeting of the agency's executive board.
He said infection levels varied "from urban to rural, it varies between different groups".
"But what it does mean is that the vast majority of the world remains at risk," he said.
WHO chief Tedros Adhanom Ghebreyesus, meanwhile, told the meeting that the pandemic should serve as a "wake-up call for all of us".
"We must all look in the mirror and ask what we can do better," he said.
Dr Tedros pushed back at criticism of the UN agency's handling of the pandemic. He said the agency from the start had "worked around the clock to support countries to prepare and respond to this new virus".
Dr Tedros, wearing a black face mask with a colourful pattern on the sides, also vigorously defended the reform process at the organisation over the past three years, but acknowledged it should be speeded up.
"We're not on the wrong path. We're on the right path, but we need to go faster," he said.
The executive board, which is made up of representatives from 34 countries who are elected for three-year periods, is meeting for two days this week for only its fifth special session.
It aims to evaluate progress towards implementing an "impartial, independent and comprehensive evaluation" of the WHO's response to the pandemic, as requested by member states.
Dr Tedros said countries were being encouraged "to come with new ideas".
"We have to be open to change and we have to implement changes now."
He stressed for instance the need for "robust peer-review" of countries' records on health.
He suggested that the Universal Periodic Review at the UN Human Rights Council, where each country's rights situation is evaluated every few years, could serve as inspiration.
The WHO has faced harsh criticism for its pandemic response, in particular from the United States, which under President Donald Trump has begun withdrawing from the organisation it accuses of sounding the alarm too late.
Dr Tedros has flatly denied that. The global agency, he said, had acted swiftly as soon as it received word of the new virus, and declared the highest level of alert on January 30.
The organisation has also been criticised for slow or changing recommendations on the best measures to take in halting the spread of the virus, including on the importance of wearing face masks.
Dr Tedros said the WHO put in massive effort to provide up-to-date and accurate information in the face of a rapidly-developing global crisis.
"Ten months ago, this virus was completely unknown to the world," he said.
"We have now published more than 400 guidance documents for individuals, communities, schools, businesses, industries, health workers, health facilities and governments."
Dr Tedros said WHO didn't have the mandate or the capacity "to do everything" but was uniquely positioned to co-ordinate the global response.