The public health risks resulting from the COVID-19 virus remain high globally, with the virus circulating in all countries, a senior expert from the World Health Organization (WHO) said on Friday.

According to estimates based on wastewater analysis, the actual circulation of COVID-19 is two to 19 times higher than the number of reported cases, Maria van Kerkhove, the interim director of the WHO responsible for epidemic and pandemic preparedness and prevention, told a special briefing in Geneva.

She also expressed concerns regarding the emergence of post-COVID conditions (also called "long COVID") affecting multiple organs.

While there has been a drastic reduction in COVID-related deaths since the peak, around 10,000 deaths per month are still reported from 50 countries.

Van Kerkhove expressed concerns about the evolving nature of the virus, with the COVID-19 JN.1 variant representing around 57 percent of global sequences analyzed by the WHO.

Defined by specific criteria, including symptoms like severe fatigue, lung impairments, neurologic issues, and cardiac impairments persisting for four to 12 months or longer after the acute phase of the disease, the post-COVID condition is a matter of concern, she said.

Estimates suggest that one in 10 infections could lead to post-COVID conditions, including severe cases. "No treatments are available yet because it's still so new," van Kerkhove said. "There is insufficient attention and funding dedicated to this area," she added.

She also warned of a rapid increase in the number of influenza infections in the northern hemisphere, with influenza positivity standing at around 20-21 percent in week 51 of 2023.

The expert also emphasized the need for simultaneous flu and COVID vaccination to mitigate the burden on healthcare systems, and called for more booster vaccination, which is at a low level globally, with only 55 percent of older adults (over 75 or 80) having received a dose.

By the end of December 2023, more than 7 million people had been reported to the WHO as having died from COVID-19.