Covid-19 is yet to settle into a “seasonal or predictable” pattern, global health leaders have said.

The World Health Organisation (WHO) dismissed the notion that the virus was “through it in the northern hemisphere until next winter” as it highlighted rising cases of the virus in the UK.

And it warned that deaths will follow any rise in cases.

The latest data from the Office for National Statistics (ONS) Covid-19 Infections Survey showed an increase in cases across the whole of the UK.

Dr Tedros Adhanom Ghebreyesus, director general of the WHO, told a media briefing: “After several weeks of declines, reported cases of Covid-19 are once again increasing globally.

“These increases are occurring despite reductions in testing in some countries, which means the cases we are seeing are just the tip of the iceberg.

“And we know that when cases increase, so do deaths.

“Continued local outbreaks and surges are to be expected, particularly in areas where measures to prevent transmission have been lifted.

“Each country is facing a different situation with different challenges, but the pandemic is not over.”

Dr Mike Ryan, executive director of the WHO’s health emergencies programme, added: “The virus is still moving around quite easily and in the context of waning immunity and the fact that vaccines don’t work perfectly against infection, the likelihood is that this virus will echo around the world.

“It will be high on some parts and sometimes it will move and be higher again, it will move to another area where immunity is waning.

“And the virus will pick up pockets of susceptibility and will survive in those pockets for months and months until another pocket of susceptibility opens up.

“This is how viruses work – they establish themselves within a community and they will move quickly to the next community that’s unprotected.

“So I do think it’s very important that we recognise that the transmission of this disease will occur. It will wax and wane.

“It has not settled down into a purely seasonal or predictable pattern yet.

“So the idea that we’re through it in the northern hemisphere now and we’ve got to wait till next winter – I think when we look at increasing rates for example of cases in the likes of the UK, I think we need to be very, very, very vigilant.

“We need to be very cautious. We need to watch this very carefully.”

Dr Maria Van Kerkhove, the WHO’s technical lead on Covid-19, suggested that there are many reasons behind the increase in cases.

She said that cases of the Omicron variant of the virus were “transmitting at a very intense level around the world”,  including the BA.2 version of this variant which “is the most transmissible variant we have seen to date”.

Meanwhile many public health measures have been eased which “provides the virus an opportunity to spread” and vaccination coverage around the world is “incomplete”.

And “misinformation” about the virus is “causing a lot of confusion” she added.

“We completely understand that the world wants to move on from Covid-19, but this virus spreads very efficiently between people and if we don’t have the right interventions in place, the virus will take opportunities to continue to spread,” she said.

On Monday Health Secretary Sajid Javid said that a rise in Covid infections was to be “expected” following the easing of Covid-19 restrictions in England.

But he insisted that the UK remains in a “very good position” with regards to the virus.

Covid-19 infections are rising in all four UK nations for the first time since the end of January, with levels in Scotland already at a record high, according to the latest ONS estimates.