Vulnerable people are being urged to get vaccinated after official figures revealed a huge spike in flu cases over the past week.
According to Public Health England (PHE), the number of people hospitalised by the illness rose by 50% over the last seven days, while there was a 65% increase in the number of flu patients admitted to intensive care.
GPs also saw a sharp rise in cases - up 78% on the previous week.
The figures come after it was revealed on Thursday that A&E waiting times have reached the worst level on record, with 300,000 patients waiting longer than they should for care in December.
PHE medical director Paul Cosford said: “Our data shows that more people are visiting GPs with flu symptoms and we are seeing more people admitted to hospital with flu.
“We are currently seeing a mix of flu types, including the A(H3N2) strain that circulated last winter in the UK and then in Australia.
“The A(H3N2) strain particularly affects older, more vulnerable age groups.”
Cosford added: “We encourage anyone who is eligible to take up their offer of the flu vaccine – it is not too late.”
Who has already been vaccinated?
Adults over 65 - 71.3%
Adults with a long-term health condition - 46.9%
Pregnant women - 45.5%
Three-year-olds - 40.8%
Two-year-olds - 42%
There have been 48 flu-related deaths in the UK this winter, 24 of which happened in the last week of 2017.
Earlier this month, PHE wrote a letter to GPs warning about ‘Japanese flu’ - otherwise known as influenza B/Yamagata - which is not included in this year’s main flu vaccine.
The strain has been detected in a number of hospitals and care homes across the south west of England.
Advice for people with flu
People concerned about flu-like symptoms should stay at home. PHE emphasises that patients should seek advice from a local pharmacist before contacting their GP.
Patients can contact their GP, or call NHS 111, to seek further advice. People with flu should get plenty of rest, keep warm, take paracetamol or ibuprofen to lower their temperature and treat aches and pains, and drink lots of water to avoid dehydration.
For most healthy people, recovering from flu can take roughly a week. However, for those that are more vulnerable, it can be more severe and it is important to be aware of this and seek help when needed.
Dr Steve Iley, medical director for Bupa UK, told HuffPost UK: “If you experience sudden chest pains, difficulty breathing or coughing up blood, you should call 999 to seek immediate help.”