The UK is experiencing its worst flu season since 2011, according to figures.
In England, the number of people visiting their doctor with flu has gone up by more than 150 per cent since the start of the year, analysis by the Royal College of GPs has found.
An estimated 31,300 patients went to their GP practice with influenza-like-illness between January 8 and 14 - a increase of more than 9,000 on the previous week.
There were 17 further deaths from flu in the last week, taking the total number of flu-related deaths this winter to 120, the latest figures show.
Public Health England (PHE) also said there was an 11 per cent increase in the flu hospitalisation rate, along with a 42 per cent increase in the GP consultation rate with flu-like illness compared to the previous week.
Professor Paul Cosford, PHE medical director, said: "Our data continues to show that more people are visiting GPs with flu symptoms and we are seeing more people admitted to hospital with flu.
"In terms of hospital admission, this is the most significant flu season since the winter of 2010/11."
Professor Simon de Lusignan, medical director at the Royal College's Research and Surveillance Centre, added: "Unsurprisingly given what we've been hearing anecdotally from GPs, rates of influenza-like illness have risen again.
"Whilst flu rates in primary care are still within what we term the 'medium threshold', the virus does seem to be affecting patients aged over 65 most, with rates moving into the 'very high threshold'.
"As ever, flu is unpredictable so it remains impossible to speculate how rates will change in the coming weeks - they may increase further, they may level out or even decline."
Wales, Scotland and Northern Ireland have also seen increases.
Figures from Health Protection Scotland showed that 114 people per 100,000 of the Scottish population were reported as having a flu-like illness in the week ending January 14, up from 107 per 100,000 the week before.
Medical director of PHE, Professor Paul Cosford, said last week that doctors are seeing “a mix of flu types” as he told people it “is not too late” to get vaccinated.
They include a deadly strain of the virus, known as “Australian flu”, A(H3N2), which got its name after circulating in the UK last winter before spreading to Down Under.
The strain particularly affects older, more vulnerable age groups.
Meanwhile cold snap is expected to hit the north of England over the coming days, which NHS doctors say could lead to a further increase in illness.