The number of flu cases in hospital is seven times higher than last month, latest figures show.
New data from NHS England shows there were 3,746 patients a day in hospital with flu last week, up from 520 a month ago.
Of those in hospital last week, 267 were in critical care beds.
The NHS has warned the rise in flu cases is continuing to put pressure on health services.
Bed occupancy remains particularly high, with more than nine in 10 beds filled (over 93%) compared to 86% for the same period last year.
The number of free beds was at the lowest seen for at least six years.
Professor Sir Stephen Powis, NHS national medical director, said: “Sadly, these latest flu numbers show our fears of a ‘twindemic’ have been realised, with cases up seven-fold in just a month and the continued impact of COVID hitting staff hard, with related absences up almost 50% on the end of November.”
NHS staff have also been severely impacted by winter viruses. The total number of staff off sick is up a fifth on the end of November, from 52,556 to 63,296 a day.
Delayed discharges also continue to take up hospital capacity, with 12,313 beds a day taken up by patients who no longer met the criteria to reside.
Nearly 600,000 calls were made to the 111 service – up more than two thirds from 365,338 this time last year.
“It is clear this is no time to be complacent and the risk of serious illness is very real, so with nearly 350,000 available vaccination appointments next week it is important that everyone eligible comes forward and gets their Covid and flu jabs at the earliest opportunity,” Prof Powis continued.
Staff have continued to go above and beyond to try and mitigate the impact of industrial action which took place on Thursday 21 December. On that day, hours were lost to ambulance handover delays.
Around this time last year (26 Dec 2021), there were only 34 patients in hospital with flu, two of whom were in critical care.