Video report by ITV News Correspondent Rebecca Barry
The Government wants to widen its programme before Christmas in England to 30 million people, with free jabs for those aged 50 and over and 11-year-olds.
Last year, around 15 million people received a jab against seasonal flu.
Experts are concerned about the consequences of a potentially "devastating" double whammy of Covid-19 cases and seasonal flu and the impact this could have on the NHS.
At the moment, the free NHS flu programme is for people aged 65 and over, pregnant women, people with certain conditions such as kidney disease, asthma or heart disease and carers or those in care homes.
Flu jab eligibility
People aged 50 and over
People with certain conditions
Carers or those in care homes
Frontline health and social care workers
Children over six months with a long-term health condition
Children aged two and three
Children in primary school
Children aged 11 by the end of August this year
Anyone living in a household with somebody on the NHS shielded patient list
Source: UK Government
Frontline health and social care workers are also eligible to receive the flu vaccine.
The flu jab is also free for children over six months with a long-term health condition, those aged two and three and those in primary school.
This programme will now be extended to include children who are aged 11 by the end of August this year (the first year of secondary school) and anyone aged 50 and over, who will be vaccinated later in the year.
Anyone living in a household with somebody on the NHS shielded patient list for Covid-19 will also be eligible for a free jab.
Experts hope GP surgeries will focus on high-risk groups before those aged over 50 in the fit and healthy range.
Not all GP surgeries will have enough fridge space to accept all the doses of the vaccine that they will need.
The Government hopes NHS and social care workers will see it as their professional responsibility to get the flu jab, but have not ruled out making it mandatory in future years.
During the winter 2019/2020 flu season, 72.4% of people aged 65 and over got their jab in England, as did 44.9% of those in high-risk groups aged six months to 64.
Overall, 74.3% of frontline health workers had their jab.
The uptake figure is known to be much lower for social care staff.
Health Secretary Matt Hancock said: “It’s mission critical that we pull out all the stops to get ready for winter, and the Prime Minister has already announced £3 billion to protect the NHS.
“We are now taking another important step to help protect the wider public by giving the flu vaccination to more people than ever before.
“This will be the biggest flu vaccination programme in history, and will help protect our NHS as we head into winter.
“If you are eligible for a free vaccine, whether it’s for the first time or because you usually receive one, then I would urge you to get it, not just to protect yourself, but to protect the NHS and your loved ones, from flu.”
England’s chief medical officer, Professor Chris Whitty, said: “Flu can have serious consequences and vulnerable people can die of it.
“Having the vaccine protects you, and helps reduce transmission to others.
“This winter more than ever, with Covid-19 still circulating, we need to help reduce all avoidable risks.
“Vaccinating more people will help reduce flu transmission and stop people becoming ill.”
Jonathan Ashworth, Labour’s shadow health secretary, said: “Flu, alongside a second coronavirus wave, could be devastating. That is why Keir Starmer demanded that a comprehensive flu vaccination programme be put in place ahead of the winter, including free vaccinations for the over 50s.
“It’s welcome ministers have listened to Labour but they must offer a guarantee that the programme will be offered to all over 50s this winter. We will do all we can locally and nationally to encourage take up of the flu vaccine.”
More people need to be encouraged to take up routine vaccinations as we recover from Covid-19, BMA warns
The British Medical Association (BMA) said the expanded flu vaccination programme was “sensible given the current health climate”.
Dr Richard Vautrey, BMA GP committee chairman, said: “Whilst GP practices continue to work hard to do all they can to support patients during the Covid-19 pandemic, they are also very aware of the vital importance this winter of protecting as many people as possible from the serious impact of influenza.
“It’s good to see the Government respond to our call to expand the flu programme but we will also need their support to encourage as many eligible people as possible to get a flu immunisation, as well as ensure vaccination supplies reach practices quickly and in sufficient quantities to meet patient need.”