Hospital admissions have risen 40 per cent in a week and for the first time since the pandemic began, people are being admitted to hospital with flu at a higher rate than for Covid-19.
NHS data shows the rate of flu admissions was 6.8 per 100,000 people in the week to December 11 — up from 3.9 the previous week — and 6.6 for Covid.
The number of flu patients in hospital increased from 966 to 1,377 in the week.
Dr Conall Watson, of the UK Health Security Agency (UK HSA) said flu was now circulating widely.
"We have seen a sharp rise in the rate of hospitalisations for flu this week, particularly among the under-fives and over-85s," he said.
“Admissions are now at the highest point since the 2017-18 season and we are expecting case numbers to continue increasing as we move further into winter.”
An analysis of the NHS data found infection rates were more than eight times higher than expected at this time of year.
Dr Jamie Lopez Bernal, a consultant epidemiologist at UK HSA, said: “We’re seeing rises in flu, Covid and other winter viruses as people mix more indoors this winter.
“Covid hospitalisations are highest in the oldest age groups, so it is particularly important that everyone who is eligible continues to come forward to accept their booster jab.
“If you are unwell this winter, please try to stay at home and avoid contact with other people, particularly elderly or vulnerable people — this will help stop infection from spreading.”
UK HSA has recommended that anyone eligible for a free flu vaccine gets it.
Anyone aged 50 and over, all primary-age schoolchildren and some secondary-age children can get the free jab.
It is also offered to pregnant women, care home residents, frontline health and social care staff, carers, people with a specified health condition, and household contacts of people with weak immune systems.
The NHS also has to deal with the biggest treatment backlog in its history. Nurses and ambulance paramedics are striking over pay, and doctors have warned the NHS is “in danger of complete collapse”.
A poll carried out by the British Medical Association found more than two in five of the most senior hospital medics are planning to leave in the next year.