The large rise means England, Wales, Scotland and Northern Ireland are now all experiencing a medium-level flu epidemic, according to European classifications.
GP consultations rose from 21.0 per 100,000 patients in week 52 of 2017 to 37.3 per 100,000 in the first week of 2018 in England – a 78% rise. Consultations must exceed 24.2 to be considered moderate, and surpass 68.7 to be considered high.
Meanwhile, rates soared by 133% in Wales, 132% in Scotland and 132% in Northern Ireland.
Current levels in England stand around twice as high as they did a year ago in week 1 of 2017.
The week also saw 240 new ICU admissions for patients with confirmed influenza, alongside 758 hospitalised confirmed influenza cases – at a time when hospitals are already straining at the seams as demand outstrips capacity.
This puts hospital cases at a rate of 7.38 per 100,000 – far above the ‘very high’ impact threshold of 4.89 per 100,000.
A total of 27 deaths in the UK were reported during the week. This means there have been a total of 664 ICU admissions across the entire season so far, and 85 confirmed deaths.
Public Health England medical director Professor 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.
'We encourage anyone who is eligible to take up their offer of the flu vaccine – it is not too late.'