CNN  — 

The novel coronavirus may have infected about one in 10 people globally, meaning the majority of the world remains vulnerable to Covid-19, a World Health Organization official has said.

“Our current best estimates tell us that about 10% of the global population may have been infected by this virus,” Dr. Mike Ryan, director of the WHO’s Health Emergencies Programme, said at a WHO executive board meeting Monday.

“This varies depending on country, it varies 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,” Ryan added.

There are more than 35.5 million confirmed Covid-19 cases globally, according to the widely-used Johns Hopkins University dashboard, but WHO and other experts say that is almost certainly an enormous undercount. Over the summer, the US Centers for Disease Control and Prevention said cases in the US had likely been undercounted by at least 90%.

With a global population of about 7.7 billion people, Ryan’s estimate would mean about 770 million have been infected – but most have not been diagnosed or counted.

Ryan noted Monday that Southeast Asia continues to see a surge in cases, while Europe and Eastern Mediterranean regions were seeing an increase in cases and deaths. However, he noted that the situation in Africa and the Western Pacific was “currently rather more positive.”

Worldwide, countries are struggling to contain resurgent outbreaks and are reintroducing measures in a bid to curb the spread of the virus.

“We are now heading into a difficult period. The disease continues to spread,” Ryan said.

WHO warns of virus “fatigue”

The WHO’s Europe director Hans Kluge warned Tuesday of “fatigue” surrounding the virus, noting that survey data from the region showed that apathy has reached high levels in some nations.

“Although fatigue is measured in different ways, and levels vary per country, it is now estimated to have reached over 60% in some cases,” Kluge said in a statement.

Kluge said that “these levels of fatigue are to be expected” during such a protracted public health emergency, where citizens have made “huge sacrifices.”

“Although we are all weary, I believe it is possible to reinvigorate and revive efforts to tackle the evolving Covid-19 challenges that we face,” he said.

Only four European countries are now measuring below a crucial level of Covid-19 cases, according the latest figures Monday, with the European Centre for Disease Prevention and Control’s (ECDC) warning in its latest risk assessment the risk of Covid-19 is high, with a very high probability of infection, while vulnerable individuals face a “very high impact” from the disease.

Overall cases in the US are on the rise as well, with the country reporting more than 50,000 daily cases on Friday and Saturday. The last time the US saw more than 50,000 cases back to back was in mid-August, and the country’s leading infectious disease expert Dr. Anthony Fauci has warned that the country is still behind on testing.