A booster vaccine programme is being rolled out across the country from Monday amid concerns over a new Covid variant.
People living in care homes and those who are housebound will be the first to get the flu and coronavirus jabs.
The roll out is beginning earlier than planned after 34 cases of a new coronavirus strain were detected in the UK.
The variant, known as BA.2.86, has not been classified as “of concern” but scientists have said it carries a high number of mutations. The UK Health Security Agency (UKHSA) is watching it closely.
Professor Susan Hopkins, Chief Medical Advisor at the UKHSA, told Sky News: “As with all new variants we're learning.
“We don't know enough to be able to tell you how concerned you should be. It's a very different situation than we have been in in 2020 and 2021. We have all got pre existing immunity at this point, through vaccines or infection.
“The reason for the booster campaign for those most at risk is because their immunity wanes faster.”
She added that bringing forward the booster programme was a “cautionary approach” as they do not know the severity of the strain yet. There have been fewer than 100 recorded cases of it worldwide.
Adults in the general population who are eligible for Covid and flu vaccines – including those aged 65 and over, people in at-risk groups and the immunosuppressed – will begin to be invited by the NHS to get their jabs from next week.
These groups will be able to book their jabs from September 18 through the NHS website, the NHS App or by calling 119.
GP surgeries or other local NHS services are also contacting people to offer the vaccines.
Vaccine programmes have already kicked off in Scotland, while Wales will roll out at the same time as England, and Northern Ireland officially starts its programme on September 18.
NHS England is urging people to get both jabs to avoid a potential “twindemic” of flu and Covid, which would put pressure on the health service.
NHS director of vaccinations and screening Steve Russell said: “The NHS flu and Covid vaccination programmes have been very effective in protecting those at greatest risk and we will work at speed to ensure they are protected once again this year, starting with care homes and those who are housebound today.
“With concerns arising over new Covid variants, it’s vital we adapt the programme and bring it forward for those most at risk, and so I strongly urge everyone eligible to come forward as soon as they can for this important protection in colder months.
“NHS staff have worked hard to ensure services are ready for patients to get jabbed at an earlier stage so they can get their protection as soon as possible.”
There have been enough unlinked cases of BA.2.86 detected in different parts of the country to suggest the variant is circulating among the community.
An outbreak of Covid-19 in a care home in Norfolk at the end of August saw 33 out of 38 residents test positive for the virus, along with 12 members of staff, according to the UKHSA.
Dr Mary Ramsay, head of immunisation at the UKHSA, said: “Older people and those in clinical risk groups remain at highest risk of serious illness from Covid-19.
“The vaccine continues to provide the best protection against serious illness and hospitalisation from Covid-19, so please make sure you get vaccinated when offered and encourage loved ones who are eligible to do the same.”
Children aged two to 17 will also be able to have flu vaccinations from next week.
The UKHSA is urging parents to fill out the consent forms for the nasal spray vaccine, which is administered at school and via GP surgeries.
