The number of people admitted to hospital with influenza in the first week of 2018 was six times higher than during the same period last year.

Some 758 people were hospitalized this year with confirmed flu cases, according to Public Health England. There were 110 during the same week in 2017.

There was also a rise in visits to general practitioners from people with flu-like illnesses, up from 18.8 per 100,000 people during the first week last year to 37.3 this year.

The number of people admitted to intensive care almost tripled, with 240 in the first week of this year compared to 84 in 2017.

So far, 85 people have died from the virus this winter in England, with 27 of those flu-related deaths coming in the first week of 2018.

Simon de Lusignan, medical director for the RCGP Research Surveillance Centre, said: "We can certainly say that last week … flu in England took off, crossing the medium threshold. However, given how unpredictable flu can be, it is impossible to speculate how this will progress moving forward – rates may increase further, they may level out or even decline."

The virus strain has been called "Aussie flu" because it is the same strain that gave Australia its worst flu season for nearly a decade.

Paul Cosford, medical director of Public Health England, said: "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."

The Royal College of General Practitioners said the figures show the increasing pressure on GP practices across England.

Helen Stokes-Lampard, chair of the Royal College of GPs, said: "These figures back up what GPs across the country are telling us … things are incredibly busy and demand is increasing – not just with flu but other common winter illness as well."

There has also been an increase in flu cases in Scotland.

Compared to the same period last year, flu rates went up from 24 to 107 per 100,000 people during the first week of January, Health Protection Scotland figures reveal.

During the first week of 2018, four deaths were reported to Scottish health officials out of the total of 53 intensive care cases.

The flu strain has also been linked to a number of deaths in Ireland.

The World Health Organization said up to 650,000 deaths annually are associated with respiratory diseases from flu.

This is an increase from the previous global estimate of 250,000 to 500,000. According to the United States Centers for Disease Control, most deaths occur among people who are older than 75 and those in the world's poorest regions.