The elderly and vulnerable have been urged to get their Covid-19 booster jabs as part of a “national mission” to help avoid a return to coronavirus restrictions over Christmas.

So far almost 10 million people in the UK have received a top-up jab, but around 30% of over-80s and 40% of over-50s in England are yet to receive a booster shot of vaccine, the Department of Health and Social Care said.

Three million more people in England are being invited to have their coronavirus booster jabs next week after Saturday saw a record day when more than 371,000 people had a top-up jab.

People over 50 and those most at risk from Covid-19 are eligible for a booster six months after their second jab.

Health Secretary Sajid Javid said younger relatives should urge eligible parents and grandparents to take up the offer of a booster and the flu vaccine.

He said that if “we all come together and play our part” then the country can “avoid a return to restrictions and enjoy Christmas”.

“Almost 10 million people in the UK have received their Covid-19 booster and third jabs, a phenomenal achievement in under two months,” Mr Javid said.

“As we approach this milestone, I want to thank those who have come forward and urge everybody across the nation to get vaccinated, get protected and get boosted.

“We know immunity begins to wane after six months, especially for the elderly and the vulnerable, and booster vaccines will top-up their protection to keep people safe over the winter.

“I strongly urge everybody who is eligible for a Covid-19 booster or flu vaccine to take up the offer as soon as you can.

“For those not yet eligible, please help your parents, grandparents or vulnerable loved ones get their jabs, it could save their life.

“And if you haven’t yet had your first and second vaccines, it is not too late, the NHS will always be there to welcome you with open arms.

“This truly is a national mission.

“If we all come together and play our part, we can get through this challenging winter, avoid a return to restrictions and enjoy Christmas.”

The third jab could become a requirement to avoid travel restrictions in a move which may further drive take-up of boosters.

Official guidance was updated earlier this month to say the Government “is reviewing the implications and requirements of boosters for international travel certification” and “looking at whether and how booster vaccinations could be included in the NHS Covid Pass for travel”.

But the Mail on Sunday reported that officials are divided over how soon to implement the measures and are discussing a grace period to allow people to continue to travel without quarantine if they have sought a booster six months after their second jab but have not yet been offered an appointment.

NHS England will begin inviting those who had their second dose more than five months ago, meaning they can receive their top-up as soon as it has been six months since their last vaccine.

Government guidelines state that people who are 50 and over, or aged 16 and over with a health condition that puts them at high risk of contracting Covid-19, and had their second dose six months ago are eligible to get their booster.

NHS England said eight million people were vaccinated by Saturday out of 12 million people that have been invited.

The 371,339 top-up vaccines given on Saturday was 12.4% higher than the previous high of 330,445 on October 31.

By next week, 16 million invitations for a booster will have been sent since the NHS booster programme began.

Dr Nikki Kanani, deputy lead for the NHS vaccination programme in England, said: “More than 371,000 people were recorded as receiving a top-up yesterday, meaning almost 8.5 million have received one in the seven weeks since the latest phase of the programme launched.

“With winter fast approaching I would urge anyone who has not yet had a booster – or indeed a first or second dose – to not delay but take up the offer to protect themselves, their family and their friends.

“People can now walk-in without an appointment to get their top-up vaccination and from tomorrow can book in an appointment a month in advance of becoming eligible – so there is no excuse to not get the lifesaving vaccine and people should do so as soon as they can.”

Text invites will come from NHSvaccine and will include a link to the NHS website, enabling anyone eligible to book an appointment at a convenient site nearby.

People who have not received their invitation can book an appointment on the NHS website or call 119.

Eligible people can also attend local walk-in sites without an appointment and can find their nearest walk-in through the online site finder.

More than 88 million vaccines have already been delivered and nine in 10 adults have had their first dose since December 2020 when Margaret Keenan received the first jab outside of a clinical trial.