New data has emerged showing that Covid infection levels have reached a new record high after a senior health official said findings that the Omicron variant is milder offer a “glimmer of Christmas hope”.

An estimated 1.7 million people in the UK had Covid-19 in the week ending December 19, the highest number since comparable figures began in autumn 2020, the Office for National Statistics (ONS) said.

The new interim data, published on Friday, also shows that around one in 35 people in private households in England had Covid-19 in the week to December 19 – up from one in 45 in the seven days to December 16.

This is the highest estimate for England since the ONS began estimating community infection levels for England in May 2020, and is equivalent to around 1.5 million people.

In London this rises to around one in 20 people likely to test positive for Covid-19, the highest proportion for any region in England, the ONS said.

North-east England had the lowest proportion, at around one in 55.

The ONS also said that Covid infections compatible with the Omicron variant have increased in all regions in England with “substantial regional variation”, with the highest rates in London and the lowest in the North East.

The latest figures come after UK Health Security Agency (UKHSA) chief executive Dr Jenny Harries said data suggesting Omicron may be less likely to lead to serious illness than the Delta variant of coronavirus offers a “glimmer of Christmas hope”.

But she warned that it is too early to downgrade the threat from the new strain, which is still spreading rapidly across the UK.

Dr Harries told BBC Radio 4’s Today programme that more information is needed, particularly about the impact on elderly and more vulnerable patients.

She added: “There is a glimmer of Christmas hope in the findings that we published yesterday, but it definitely isn’t yet at the point where we could downgrade that serious threat.”

The UKHSA estimates that someone with Omicron is between 31% and 45% less likely to attend A&E and 50% to 70% less likely to be admitted to hospital than an individual with the Delta variant.

The rapid spread of Omicron has seen it become the “dominant strain now right across the UK”, and Dr Harries said cases are still doubling across “most regions” of the country.

Dr Harries added: “What we have got now is a really fine balance between something that looks like a lower risk of hospitalisation – which is great news – but equally a highly transmissible variant and one that we know evades some of our immune defences, so it is a very balanced position.”

The UKHSA data has fuelled speculation in Westminster that further restrictions can be avoided in England after Christmas.

Tony Blair has said “you’re an idiot” if you have no health reason not to get vaccinated against Covid but still have not had the jab.

In an interview with Times Radio, the former prime minister said it would now be “incredibly difficult” for the government to introduce another full lockdown.

“One of the reasons I’m not in favour of shutting everything down is I’m not sure with this Omicron thing there’s anything you can do,” he said. “You’ve just got to give people the best protection.”

Blair added: “If you’re not vaccinated at the moment and you’re, you’re eligible and you’ve got no health reason for not being vaccinated, you’re not just irresponsible, I mean, you’re an idiot. I’m sorry, I mean, truthfully you are.”

It came as Boris Johnson was urged to outline his post-Christmas Covid strategy.

The prime minister has ruled out introducing new rules before Christmas, but there is an expectation tighter restrictions will be brought in soon after.

Gillian Keegan, a health minister, warned earlier today there is “uncertainty” around people making new year’s eve plans.

“We can’t predict what the data is going to tell us before we’ve got the data,” she told LBC.

“We are trying to take a balanced and proportionate approach so that people can see their families over Christmas to try and plan some stuff. But of course it is difficult to anticipate.”

But Labour pressed for decisions to be made as soon as possible. Shadow work and pensions secretary Jon Ashworth told Sky News: “People are anticipating that some form of restrictions will come in post-Christmas, and I think we just need to give people certainty.

Elsewhere, it was reported that UK Government scientists are set to conclude that Omicron is causing a milder disease than the Delta strain in most Britons.

Politico’s London Playbook said the UK Health Security Agency is expected to publish early real-world data on the disease’s severity before Christmas, with its findings also suggesting Omicron is not necessarily mild enough to avoid large numbers of hospital admissions.