The Omicron wave may have peaked in some countries, global health leaders have said.

But the World Health Organisation (WHO) said that “no country is out of the woods yet” and it is not time to “give up and wave the white flag”.

Dr Tedros Adhanom Ghebreyesus, director general of the WHO also said that the pandemic is “nowhere near over” and warned that new variants are likely to emerge.

Dr Tedros told a press briefing: “Omicron continues to sweep the world, last week, there were over 18 million reported cases.

“The number of deaths remains stable for the moment but we are concerned about the impact Omicron is having on already exhausted health workers and overburdened health systems

“In some countries, cases seem to have peaked, which gives hope that the worst of this latest wave is done with, but no country is out of the woods yet.

“I remain particularly concerned about many countries that have low vaccination rates, as people are many times more at risk of severe illness and death if they are unvaccinated.

“Omicron may be less severe, on average, but the narrative that it is a mild disease is misleading, hurts the overall response and costs more lives.”

He continued: “Make no mistake, Omicron is causing hospitalisations and deaths, and even the less severe cases are inundating health facilities.

“The virus is circulating far too intensely with many still vulnerable.

“For many countries, the next few weeks remain really critical for health workers and health systems and I urge everyone to do their best to reduce risk of infection so that you can help take pressure off the system.

“Now is not the time to give up and wave the white flag.

“We can still significantly reduce the impact of the current wave by sharing and using health tools effectively and implementing public health and social measures that we know work.”

He said that the global vaccine sharing facility Covax delivered its one billionth dose of vaccine over the weekend but more still needed to be done to achieve vaccine equity around the world.

Dr Tedros added: “At a time of Omicron, it remains more important than ever to get vaccines to the unvaccinated.

“Vaccines may be less effective at preventing infection and transmission of Omicron than they were for previous variants but they still are exceptionally good at averting severe disease and death – this is key from preventing hospitals from being overwhelmed.

“This pandemic is nowhere near over and with the incredible growth of Omicron globally, new variants are likely to emerge, which is why tracking and assessment remain critical.”

Meanwhile Dr Mike Ryan, executive director of the WHO’s Health Emergencies programme, said that at present the global health body was “not recommending a change in the composition of the vaccine”.

But he stressed that more data and discussions are needed to “dictate what the world needs in terms of future vaccines.”

Dr Ryan also said that the primary course of the vaccine may change in future.

At present most adults in the UK have had two initial Covid-19 vaccines, typically Pfizer, Moderna or AstraZeneca, which is known as a primary course of vaccine.

Some people with compromised immune systems were offered three doses as part of their primary course.

All British adults were subsequently offered boosters.

He said: “I suspect over time, we will come up with an evolved way of looking at what we consider to be primary series.

“And it may be that a healthy adult has a primary series of two doses.

“It may be that someone in an older age group has a primary series of three or four doses.

“That’s what we’re learning and that’s why we need to collect the data to be able to understand what the long term best decisions are in deploying the vaccines that we have at our disposal.”