More than 12.6m people UK-wide have already received a third dose of COVID-19 vaccine - around three quarters of around 17m eligible as part of the first nine cohorts identified by the Joint Committee on Vaccination and Immunisation (JCVI), covering over-50s, health and care workers and clinically vulnerable patients.
Most of these 12.6m are booster doses, while some are third doses offered as part of the primary vaccination schedule to patients with severe immunosuppression at the time of an earlier dose.
The JCVI has now advised that the booster campaign will expand to cover adults aged between 40 and 49 years old.
People in this age range will be offered a booster jab six months after the date of their second dose. The booster will be an mRNA vaccine - such as the Pfizer/BioNTech or Moderna vaccines - irrespective of the product used for the first two doses.
Meanwhile, people aged 16 and 17 years old who are not in at-risk groups should now be offered a second dose of the Pfizer/BioNTech COVID-19 vaccine 12 weeks after their initial dose, the JCVI confirmed. By 7 November, just under two thirds of people in this age group had received a first dose of vaccine, according to NHS England data.
The JCVI said it was expanding the booster campaign because of evidence of waning protection in patients aged 40-49 against COVID-19.
Analysis by the UK Health Security agency shows that booster jabs increase protection against symptomatic COVID-19 infection to over 90%, with protection against more severe disease expected to be even higher.
The JCVI is continuing to monitor data on under 40s but says that at this stage there is 'no robust evidence of a decline in protection against severe COVID-19 (hospitalisation and deaths) in those aged under 40' - and that boosters in this group are not yet justified.
JCVI COVID-19 immunisation chair Professor Wei Shen Lim said: 'Booster vaccine doses in more vulnerable adults, and second vaccine doses in 16- to 17-year-olds are important ways to increase our protection against COVID-19 infection and severe disease. These vaccinations will also help extend our protection into 2022.'
Health and social care secretary Sajid Javid said: 'We are expanding the programme even further and today I have accepted the advice from the JCVI to extend the additional offer of a booster jab to people aged 40 and over and offer a second dose of a vaccine to all young people aged 16 to 17 as part of the primary vaccination schedule. All four parts of the UK intend to follow the JCVI’s advice.
'I have asked the NHS to prepare to offer those eligible a vaccine as soon as possible. We know immunity to COVID-19 begins to wane after six months. The JCVI will keep under review whether the booster programme should be extended to all people under the age of 40 and I look forward to receiving their advice in due course.'