Health chiefs are urging Britons to get jabbed as soon as possible amid warnings up to 60,000 people could die from flu this winter.
Experts fear a massive surge in cases because social distancing measures kept infections low last year, reducing population immunity.
The Government has launched the biggest flu programme in the history of the NHS, with more than 35 million people in England eligible for a free vaccine.
Covid booster jabs are also being rolled out, with around 1.7 million people given these third jabs so far and around 28 million people in England eligible.
Health Secretary Sajid Javid is calling on people to protect themselves against both viruses after experts predicted high infection rates could push the health service to breaking point.
It comes as colder weather and darker evenings lead to increased social contact indoors, making it easier for the viruses to spread.
The Covid booster must be given no earlier than six months after the second dose of any coronavirus vaccine, according to guidance from the Joint Committee on Vaccination and Immunisation (JCVI).
Professor Jonathan Van-Tam (pictured), England’s Deputy Chief Medical Officer, said: ‘Not many people got flu last year because of Covid-19 restrictions, so there isn’t as much natural immunity in our communities as usual
In some regions, people may be offered the Covid jab in one arm and the flu vaccine in the other, although this will not be available everywhere.
Mr Javid said people should not delay having either jab when invited to get them – either on separate occasions or at the same time.
He added: ‘The Covid-19 vaccine programme is a fantastic example of how successful vaccination programmes can be – with around 130,000 lives saved.
‘It is vital we continue that incredible progress with all those eligible ensuring they get both their flu and Covid-19 booster injections as soon as they are invited.’
A report from the Academy of Medical Sciences, published earlier this year, assessed how the triple threat of coronavirus, flu and respiratory syncytial virus (RSV) might affect the NHS this winter.
It found that hospital admissions and deaths from flu and RSV could be more than double those seen in a normal year, leading to as many as 60,000 flu deaths and 40,000 children in hospital with RSV.
A recent survey of 3,000 people for ministers found that nearly one third (32 per cent) were unaware that flu and Covid-19 can circulate at the same time.
A quarter (26 per cent) did not know that flu can be fatal and over half (55 per cent) underestimated the number of people who die from flu in an average year in England, which is around 11,000.
Almost one in ten (9 per cent) thought the Covid jab would protect them against flu.
Professor Jonathan Van-Tam, England’s Deputy Chief Medical Officer, said: ‘Not many people got flu last year because of Covid-19 restrictions, so there isn’t as much natural immunity in our communities as usual.
‘We will see flu circulate this winter; it might be higher than usual and that makes it a significant public health concern.
‘Covid-19 will still be circulating and with more people mixing indoors, sadly some increases are possible.
‘For the first time we will have Covid-19 and flu co-circulating.
‘We need to take this seriously and defend ourselves and the NHS by getting the annual flu jab and the Covid-19 booster when called.’
Experts fear a massive surge in cases because social distancing measures kept infections low last year, reducing population immunity [Stock image]
More than 80 per cent of people aged 65 and over had their flu jab last year – exceeding a global target of 75 per cent. The NHS has set an ambition to reach at least 85 per cent of this group this flu season.
It also hopes to reach at least 75 per cent of people with underlying health conditions, such as asthma and heart disease, at least 75 per cent of pregnant women and at least 70 per cent of eligible children.
All frontline health and social care workers will also be offered a flu jab, with an ambition that at least 85 per cent will accept.