The fast-spreading variant, the most prevalent in the United States with an estimated more than 17% of cases, has been behind upticks in the virus across the country and also has been detected in China, South Korea, Japan and Canada, among other countries.

"Collectively, available evidence does not suggest that EG.5 has additional public health risks relative to the other currently circulating Omicron descendent lineages," the WHO said in a risk evaluation.

A more comprehensive evaluation of the risk posed by EG.5 was needed, it added.

COVID-19 has killed more than 6.9 million people globally, with more than 768 million confirmed cases since the virus emerged. WHO declared the outbreak a pandemic in March 2020 and ended the global emergency status for COVID-19 in May this year.

Maria Van Kerkhove, the WHO's technical lead on COVID-19, said EG.5 had an increased transmissibility but was not more severe than other Omicron variants.

"We don't detect a change in severity of EG.5 compared to other sublineages of Omicron that have been in circulation since late 2021," she said.

Director General Tedros Adhanom Ghebreyesus deplored that many countries were not reporting COVID-19 data to WHO.

He said that only 11% had reported hospitalizations and ICU admissions related to the virus.

In response, WHO issued a set of standing recommendations for COVID, in which it urged countries to continue reporting COVID data, particularly mortality data, morbidity data, and to continue to offer vaccination.

Van Kerkhove said that the absence of data from many countries was hindering efforts to fight the virus.

"About a year ago, we were in a much better situation to either anticipate or act or be more agile," she said. "And now the delay in our ability to do that is growing. And our ability to do this is declining."