A major warning has been issued by health bosses over a predicted “twindemic” of flu and Covid-19 this winter.
The UK Health Security Agency says low natural immunity against flu, combined with resurgent Covid strains, could kill tens of thousands.
It is calling on all eligible groups to quickly get double-jabbed against both viruses.
A dangerous H3N2 flu strain is dominant globally and has already been detected in Britain. Experts predict a deadly flu surge starting early – possibly from next month – driven by cases in children.
Dr Susan Hopkins, UKHSA Chief Medical Advisor, said: “There are strong indications we could be facing the threat of widely circulating flu, lower levels of natural immunity due to less exposure over the last three winters and an increase in Covid-19 with variants that can evade the immune response.
“If you are elderly or vulnerable, you are at greater risk, so getting the flu jab is a sensible, potentially life-saving thing to do.”
The UKHSA fears a flu season as big as that seen in 2017/18, which caused 40,000 hospital admissions and around 20,000 deaths.
Steve Russell, NHS England vaccinations director, said: “This winter could be the first time we see the effects of the so called ‘twindemic’ with both Covid and flu in full circulation.
“If you have been offered a flu vaccination or Covid booster, book in as soon as possible.”
Only three million people have had their flu jab so far, out of 33 million eligible.
Flu jabs can be booked via GPs while Covid autumn boosters can be arranged via the National Booking Service online.