The UK's National Health Service (NHS) said it has started delivering COVID-19 booster vaccines to people in eligible groups of over-50s from Thursday.

In line with new guidance set out by the Joint Committee on Vaccination and Immunisation (JCVI) earlier this week, the National Health Service vaccination programme will move to the next phase for people who had their second COVID-19 vaccine at least six months ago, administering a booster or top up.

Hospital hubs have started vaccinating frontline health and care workers as well as identifying other eligible patients for their booster vaccine immediately, with local vaccination services led by General Practitioners (GPs) to follow in the coming days.

"Now that the decision has been taken by the JCVI and once the relevant checks are in place, the NHS will invite you for your booster vaccination," said Dr Nikki Kanani, an Indian-origin General Practitioner and deputy lead for the NHS COVID-19 vaccination programme.

"There is no need to contact the NHS -- we will be in touch with you when it is your turn to get your booster vaccine -- at least six months on since your last dose. The fast preparations of staff to get ready for boosters comes on the back of our biggest vaccination drive in health history which has delivered more than 77 million vaccinations across the country," she said.

The full booster vaccination rollout will begin from next week, as more vaccination centres and community pharmacy-led sites come online following final checks, giving people further protection from the virus ahead of winter. People will get a call or text from their local GP-led site to get the vaccine shot, or will be invited by the National Booking Service, which will start issuing invitations from next week.

"We know vaccines save lives and with every jab our wall of defence across the country gets higher, with more than 112,300 lives saved and over 24 million cases prevented in England alone," said UK Health Secretary Sajid Javid.

"I urge everyone who is eligible to come forward for their booster when invited, to prolong the protection that the vaccine offers those most at risk as we approach the winter months," he said.

Those who are eligible include: those living in residential care homes for older adults; all adults aged 50 years or over; frontline health and social care workers; all those aged 16 to 49 years with underlying health conditions that put them at higher risk of severe COVID-19 (as set out in the green book), and adult carers; and adult household contacts of immuno-suppressed individuals.

In line with advice from the Joint Committee on Vaccination and Immunisation, people will receive either one dose of the Pfizer vaccine or half a dose of the Moderna vaccine. UK experts concluded that booster jabs are effective for topping up protection for people who have had both of their vaccine doses from, at the very least, six months after their second dose.

The UK government has also accepted the advice of its Chief Medical Officers (CMOs) to offer a single dose of the Pfizer vaccine to all healthy 12-15-year-olds, and the NHS is working with partners and the School Age Immunisation Service to deliver this, with children due to start getting the vaccine in schools from next week.