Covid-19 infections in the UK have jumped by nearly 800,000 in a week, with some parts of the country nearing the record levels seen during the spring.

Hospital numbers are also continuing to increase, driven by the spread of the latest coronavirus subvariants Omicron BA.4 and BA.5.

A total of 3.5 million people in private households are estimated to have had Covid-19 last week, up 29% from 2.7 million the previous week, according to the Office for National Statistics (ONS).

This is the highest estimate for total infections since mid-April but is still below the record of 4.9 million seen at the peak of the Omicron BA.2 wave at the end of March.

Sarah Crofts, ONS head of analytical outputs for the Covid-19 infection survey, said: “Infections are showing no signs of decreasing, with rates approaching levels last seen in March at the peak of the BA.2 wave.

“Rates have continued to increase across the UK and among all age groups. We will continue to closely monitor the data.”

Everyone over the age of 50 will be offered a fresh Covid-19 jab this autumn, to boost protection ahead of possible further waves of the virus, the UK Health Security Agency announced on Friday.

Other groups eligible for the dose will include frontline health and social care workers and those aged five to 49 in a clinical risk group, including pregnant women.

Professor Anthony Harnden, deputy chairman of the Joint Committee on Vaccination and Immunisation, said: “The Covid-19 boosters are highly effective at increasing immunity and, by offering a further dose to those at higher risk of severe illness this autumn, we hope to significantly reduce the risk of hospitalisations and deaths over the winter.”

The virus currently remains most prevalent in Scotland, where 334,000 people were estimated to have had Covid-19 in the week to July 7, or around one in 16, the ONS said.

This is up from 312,800, or one in 17, and is the highest estimate for Scotland since the start of April.

In England, 2.9 million people were likely to have had Covid-19 last week, the equivalent of around one in 19.

This is up from 2.2 million, or one in 25, the previous week.

Wales has seen infections jump to 183,500, or one in 17 people, up from 149,700, or one in 20.

In Northern Ireland, infections have increased to an estimated 107,600 people, or one in 17 – the highest level since the beginning of April, and up from 98,400, or one in 19.

James Naismith, professor of structural biology at Oxford University, said that Scotland had “most likely” reached a peak in infections and that England “is on its way” to this level, but the growing prevalence of the virus would “keep the NHS under pressure, especially as it reaches the elderly”.

He added: “Around 98% of the population have Covid-19 antibodies at a high level. The current strain of Omicron has evolved to evade this immune response to cause infection. It’s very good at it – the prevalence is high for summer. It would have been higher in winter.

“Neither vaccination nor previous infection – with a non-Omicron strain – give strong protection against Omicron infection; this is why infection numbers are high despite us all having antibodies. But the high level of antibodies in the population is why current levels of infection are not killing many more people.”

Prevalence of Covid-19 in England is estimated to be highest among people from school year 12 to age 24, where 6.5%, or one in 15, were likely to have had the virus last week.

The next highest estimate was for 25 to 34-year-olds, at 6.2%.

The figures come amid signs the month-long rise in the number of hospital patients in England testing positive for Covid-19 may be slowing down.

A total of 13,975 people were in hospital as of 8am on July 15, up 14% on the previous week, NHS England said.

Seven days earlier, on July 8, the week-on-week increase stood at 31% – while it was running as high as 39% at the start of July.

The number of patients with Covid-19 is creeping closer to the levels reached during the two waves of infection earlier this year.

But if the rate of increase continues to slow, the current wave may end up peaking below the 16,600 seen at the height of the Omicron BA.2 wave in April.

Patients numbers in Scotland, Wales and Northern Ireland are currently around three-quarters of the peak reached during the BA.2 wave.

Around six in 10 hospital patients who test positive for Covid-19 are being treated primarily for something else, rather than the virus.

But they will need to be kept isolated from those patients who do not have Covid, putting extra pressure on hospital staff who are already struggling to clear a record backlog of treatment.

The UK’s full Covid-19 death toll was confirmed earlier this week as having passed 200,000.

A total of 200,247 people have now had coronavirus recorded on their death certificate since the pandemic began, according to the ONS.

This includes all instances where Covid-19 has been mentioned on someone’s death certificate, either as a main cause of death or a contributory factor.

Deaths involving coronavirus have remained low by historic standards during each of this year’s waves, reflecting the success of vaccines in weakening the link between infection and serious illness.

Analysis by the PA news agency of ONS data shows that the number of deaths involving coronavirus occurring in the UK each week has remained mostly below 1,000 since early last year, peaking between 1,000 and 2,000 whenever infections have jumped.

By contrast, during the wave caused by the Alpha variant in January 2021, the weekly figure peaked at nearly 10,000.