More than half of people across Europe will be infected by the Omicron variant of coronavirus in the next two months, global health leaders have warned as they said Covid-19 cannot yet be called an “endemic” disease.

The European arm of the World Health Organisation (WHO) said Omicron represents a “new tidal wave” as forecasts suggest that more than 50% of people across Europe will be infected over the next six to eight weeks.

It said the region entered the new year under “intense pressure”, with more than seven million cases in the first week of January.

And it is “still a way off” to call Covid-19 “endemic”, officials said.

WHO regional director for Europe Dr Hans Henri Kluge said people should be doing “everything possible not to get infected in the first place”.

He told a press briefing: “We have entered 2022 with the countries of Europe and central Asia still under intense pressure from Covid-19.

“Today, the Omicron variant represents a new west to east tidal wave sweeping across the region, on top of the Delta surge that all countries were managing until late 2021.

“The region saw over seven million newly reported cases of Covid-19 in the first week of 2022, more than doubling over a two-week period.

“As of 10th January, 26 countries report that over 1% of their population is catching Covid-19 each week.”

He added: “It is quickly becoming the dominant virus in western Europe and is now spreading in the Balkans.

“At this rate, the Institute for Health Metrics and Evaluation (IHME) forecasts that more than 50% of the population in the region will be infected with Omicron in the next six to eight weeks.

“Data collated in recent weeks confirms that Omicron is highly transmissible and it can infect even those who have been previously infected or vaccinated.

“The currently approved vaccines do continue to provide good protection against severe disease and death, including for Omicron.

“But, because of the scale of transmission, we are now seeing rising Covid-19 hospitalisations. It is challenging health systems and service delivery in many countries where Omicron has spread and threatens to overwhelm in many more.”

Dr Kluge added: “The key message is that every individual should do everything possible not to get infected in the first place.”

Asked about whether Covid-19 is moving to an “endemic” stage, Dr Catherine Smallwood, senior emergency officer at the WHO Regional Office for Europe, said: “In terms of endemicity we’re still a way off.

“Endemicity assumes that there is some stable circulation of the virus at predictable levels and potentially known and predictable waves of epidemic transmission.

“But what we’re seeing at the moment, coming into 2022, is nowhere near that – we still have a huge amount of uncertainty, we still have a virus that’s evolving quite quickly and posing quite new challenges.

“So we’re certainly not to the point of being able to call it endemic.

“It may become endemic in due course, but pinning that down to 2022 is a little bit difficult at this stage.”

She went on: “All of this, of course, depends on how we respond to it, and widespread vaccination uptake and on an equitable basis will be very, very key in moving towards such a scenario, and we’re still a way off that.

“At the moment, the conditions for endemicity are not being met. The virus is not settling into a stable rate of transmission, and there’s still a lot of unpredictability… We hope to see that very soon rectified but it will very much depend on the actions we take collectively across Europe and across the world.”

Meanwhile, Dr Smallwood suggested that Omicron is not milder than Delta.

She told the briefing: “The reason we’re seeing a lot more milder infections across Western Europe and Israel is because of the high vaccination uptake in our population.

“That immunity is basically meaning that we’re able to tolerate, from a public health perspective, a higher degree of infection in the population.

“And, as much as we can tolerate that higher degree of infection in the population because of the vaccine coverage, we cannot necessarily tolerate the disruption that that’s bringing to our critical services.

“We cannot predict the same milder resurgence of cases, and we’re yet to see how Omicron will pan out in a situation where there are more people susceptible and immunologically naive, and that’s where we need to hold our guns, be very cautious and not jump to any conclusions about changing the strategy and letting Covid spread – that would be a grave mistake.”

On reports of a so-called Deltacron variant, she said: “(There have been) reports of a recombination between Delta and Omicron variants, and indeed we are in touch with Cyprus, who have been providing information about that.

“And it does at this stage look like it could be the result of laboratory contamination rather than a new variant or new recombination between two variants.”

Dr Kluge said WHO Europe advice encouraging people to take up an offer of a booster jab is not contrary to international WHO statements which have called for initial vaccinations to be prioritised over boosters.

He added that lockdowns and mandatory vaccines should be “tools of the very last resort”.