More than 50% of the adult UK population are now boosted after the program was accelerated this week to offer the jab to everyone aged over 18.
A total of 26.3 million have received a top-up jab in the UK - making it one of the fastest rollouts in the world.
Vaccines are the best way to protect people against COVID-19 and data from the UK Health Security Agency shows a booster vaccine increases protection against symptomatic infection from the Omicron variant to around 70%.
This week, online bookings opened to all those aged over 18, as well as walk-in sites across the country including at many hospitals, pharmacies, pop-ups and football stadiums.
Secretary of State Sajid Javid said:
We're making excellent progress in our national mission to get all adults in the UK boosted as soon as possible - but we need to go even further.
Vaccines are our best shot at tackling the Omicron variant - and it is vital people come forward to protect themselves, their loved ones and their community this winter.
It is very encouraging to see record breaking milestones and booster bookings - but I urge all of those who have not yet done so to book their booster or find a walk-in center to Get Boosted Now."
Vaccines Minister Maggie Throup said:
Thank you to everyone in the NHS, thousands of volunteers, the Armed Forces, and all those who have been involved or come forward for your booster already.
We need everyone to step forward in this national mission to Get Boosted Now and get the best possible protection against the Omicron variant.
Do not delay. Book your booster today - it might be the most important thing you do this winter."
In order to speed up the vaccine rollout across the UK, a total of 750 armed forces personnel have been drafted in to support deployment of booster vaccines, tens of thousands of volunteers have stepped up to support the national mission, and extra vaccine centres and pop-up sites have opened to make it as easy as possible for people to get vaccinated.
The 15-minute observation following a Pfizer or Moderna booster jabs was also temporarily suspended where clinically safe and appropriate to do so.
Anyone over the age of 18 can have their booster three months after their second dose, and bookings can be made one month in advance.
Dr Emily Lawson, head of the NHS vaccination program, said:
Thanks to the dedication and determination of our NHS staff, aided by our fantastic volunteers, the NHS Covid Vaccination Programme has now given a vital booster to half of all eligible adults over 18 ahead of Christmas, including more than 21 million in England.
As the NHS ramps up capacity to deliver boosters at an unprecedented rate, I would urge anyone yet to book in for their life-saving booster to do so at the earliest opportunity - it is the best way to guarantee yourself and your loved protections this winter."
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