An estimated 2.3 million people in the UK had COVID in the week up to 23 December – a substantial rise on the 1.4 million the previous week.
It is the highest number since comparable figures began in autumn 2020, the Office for National Statistics (ONS) said – while separate data also showed surging hospital admissions as NHS staff absences caused by the virus rise steeply.
Yet elsewhere there were “encouraging signs” in analysis published by the UK Health Security Agency showing that the risk of hospitalisation from the now-dominant Omicron variant was about one-third of that of Delta.
It also suggested that vaccines can work well against Omicron, with a third dose associated with an 81% reduced risk of hospitalisation when compared with the unvaccinated.
The ONS infection survey showed that in London, around one in 15 people was likely to test positive for COVID in the week to 23 December, the highest proportion for any region in England.
Infection rates increased across all four UK nations, with one in 25 in England – or around two million people – estimated to have had COVID.
The rate was one in 40 for Wales, Northern Ireland and Scotland.
England and Scotland’s rates are the highest since records began.
Separate data showed that the number of COVID patients in hospital in England had climbed to 11,452 on Thursday, the highest level since February 26.
Meanwhile, NHS England said that more than three quarters of eligible adults – 28 million people – had received their booster jab by 30 December.
One expert voiced hope that a high peak in case numbers now could mean “relatively few” by the end of January – but cautioned that there were no guarantees.
Professor Paul Hunter, an infectious diseases expert at the University of East Anglia, also pointed to the likelihood of COVID becoming an endemic infection, causing less severe illness, once the peak has passed.
Further figures revealed that 24,632 staff at NHS hospital trusts were ill with coronavirus or having to self-isolate on Boxing Day, up 31% from 18,829 a week earlier and nearly double the 12,508 at the start of the month.
Matthew Taylor, chief executive of the NHS Confederation, said the health service was facing a “perfect storm” of rising COVID hospital admissions and illness alongside increasing staff absences.
“The NHS is putting in plans to step up once again for patients with the new Nightingale surge hubs, extra support from community services and virtual wards, but there is no doubt the whole system is running hot,” he said.
“While the government seems determined not to increase restrictions in England, it is vital we all behave in ways that will not exacerbate an already dangerous situation.”
NHS England national medical director Professor Stephen Powis said: “The NHS is on a war footing, and, while staff remain braced for the worst, with COVID absence for NHS staff almost doubling in the past fortnight, keeping as many colleagues as possible at work on the front line and minimising absence, will be essential in the next few weeks.”
Professor Hunter told Sky News that “a high peak now probably means that by the end of January we will be seeing relatively few cases compared to what we are seeing at the moment”.
“We know any infectious disease that spreads really quickly reaches its peak very early, a high peak, and then generally falls quite rapidly at the other side,” he said.
“There is hope that it would peak and fall quickly. I don’t think it’s a forlorn hope. But certainly I don’t think we can guarantee that that would happen.”
Professor Hunter of the University of East Anglia said that after the current peak, the virus looked set to become an “endemic infection that will be here forever”.
“The issue though is that even if it is here forever it won’t necessarily be causing, and almost certainly won’t be causing, the severity of disease, the pressure on hospital beds, that we are seeing,” he added.
In South Africa, where the Omicron variant was first identified, a midnight to 4am curfew on movement has been lifted as the government believes the country has passed the peak of its latest wave of infections.