A new variant of the virus which causes Covid-19 was detected in the UK on August 18.
The variant, known as BA.2.86, is not classified as a “variant of concern”, but scientists have said it carries a high number of mutations.
The UK Department of Health and Social Care announced that vaccinations would start on September 11 following advice from the UK Health Security Agency (UKHSA).
It was due to start in October.
Jenny Harries, UKHSA chief executive, said: “As we continue to live with covid-19, we expect to see new variants emerge.
“Thanks to the success of our vaccine programme, we have built strong, broad immune defences against new variants throughout the population. However, some people remain more vulnerable to severe illness from covid-19.”
The UKHSA advised that speeding up the autumn vaccine programme would deliver greater protection, particularly for those at greatest risk of severe illness.
This could also reduce any potential impact on the NHS.
Ms Harries added that the potential impact of BA.2.86 was “difficult to estimate” due to “limited information” being available.
“As with all emergent and circulating covid-19 variants – both in the UK and internationally – we will continue to monitor BA.2.86 and to advise government and the public as we learn more,” she said.
People have been urged to take up the offer of the vaccines as soon as they are invited to come forward.
Health minister Maria Caulfield said the move “makes sense”.
“As our world-leading scientists gather more information on the BA.2.86 variant, it makes sense to bring forward the vaccination programme,” she said.
“It is absolutely vital the most vulnerable groups receive a vaccine to strengthen their immunity over winter to protect themselves and reduce pressure on the NHS.
“I encourage anyone invited for a vaccination – including those yet to have their first jab – to come forward as soon as possible.”