The number of influenza cases across the country doubled to two million in a week, according to data released today.
People are being urged to get vaccinated after the health chiefs have confirmed that the winter's influenza virus has begun.
This comes after weeks of very little activity reported by Public Health England (PHE).
Millions of people suffer from symptoms such as fever, chills, and muscle pain, and experts fear that this could put pressure on the already exhausted NHS.
The virus is circulating widely throughout the United Kingdom and within a week the cases have increased by 85% in England and 55% in Wales.
Meanwhile, the news about influenza has increased by 1
PHE publishes a weekly report that shows the number of flu symptoms that have been recorded in GP consultations.
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Based on how often influenza symptoms are reported for 100,000 patients each country sets its own criteria on what it considers an epidemic.
While none of the nations of origin reached the point of being yet an epidemic, England and Wales are in the "low" threshold.
This is the second step on a five-point scale towards "very high" which are epidemic levels.
Meanwhile in Scotland and Northern Ireland, levels are at the first threshold, which is the baseline.
The North East, West Midlands, North West England and Yorkshire and Humber have a "medium intensity" of cases, making it the most affected.
South East, East Midlands, South West and East of England are less affected and are at "low intensity".
Regional data are not available for Northern Ireland, Wales and Scotland.
Rates have worsened since monitoring began in September and over three months 41 p
The PHE data released today reveal that the UK had an average of 60 influenza diagnoses per 100,000 people last week.
And showed that the H1N1 strain (swine flu) was the most widespread  The health bosses have confirmed that the virus of this winter's influence has begun (image)
(Image: Getty Images)
In the previous week there was a 76% increase, which was the last week of 2018.
PHE added that the increase in cases means that influenza is having a "moderate impact" on hospitals and intensive care units.
One third of this season's flu cases requiring intensive intensive care last week – which is 205 out of a total of 666.
PHE recommends anyone who is fit to get the flu shot if they do not 39; has already done.
For the first time this winter, all primary school children are now eligible for a free nasal spray-free flu vaccine and children aged two and three years old on 31 August 2018.
This vaccine is also offered to staff working in nursing homes and nursing homes this winter who has regular contact with customers.
In addition carers, volunteers providing care or providing first aid in events organized publics, as well as the first rescuers of the community, are entitled to the vaccine.
And adults who are morbidly obese – with a body mass index of 40 or more – may also have a free jab.
Those who are not eligible for a free NHS vaccine – as healthy adults – can pay for one at their local pharmacy between £ 8 and £ 10.
To improve the effectiveness of this year, they are introduced several flu shots recommended for different age groups.
There are four different types in total – one for children (nasal spray), two for adults under 65 and one for people over sixty.
If you think you have influence, check out the symptom corrector at www.nhs.uk/conditions/flu.