The World Health Organization (WHO) on Tuesday warned against treating COVID-19 as an endemic illness like flu, rather than as a pandemic, saying the spread of the omicron variant has not yet stabilized.

Spain's Prime Minister Pedro Sanchez said on Monday it may be time to change how it tracks COVID-19's evolution to instead use a method similar to how it follows the flu, because its lethality has fallen. That would imply treating the virus as an "endemic illness," rather than a pandemic.

"We still have a huge amount of uncertainty and a virus that is evolving quite quickly, imposing new challenges. We are certainly not at the point where we are able to call it endemic," WHO's senior emergency officer for Europe, Catherine Smallwood, told a press briefing.