Britain has opted against mass Covid vaccinations for all children and teenagers, with ministers instead preparing to offer jabs to vulnerable 12 to 15-year-olds and those about to turn 18, The Telegraph can disclose.

The Joint Committee on Vaccination and Immunisation (JCVI) is believed to have advised ministers against the rollout of vaccines to all children until further evidence on the risks is available.

Instead, under guidance due to be issued on Monday, jabs will be offered to children between 12 and 15 who are deemed vulnerable to Covid or who live with adults who are immunosuppressed or otherwise vulnerable to the virus.  They will also now be offered to all 17-year-olds within three months of their 18th birthday.

The move is at odds with decisions taken in countries such as the US, Israel and France, where children over the age of 12 are being routinely vaccinated.

Teaching unions had pushed for all young people to be offered a vaccine to protect them against serious illness from Covid and to help minimise further disruption to education after three lockdowns.

However, the JCVI’s advice is expected to echo recommendations by Germany’s vaccine commission, Stiko, which said last month that only children with pre-existing conditions should be given a Covid jab.

Ministers are preparing to announce the move after months of deliberation by the JCVI. A source said the committee would keep the possibility of vaccinating all children "under review". Patients’ groups and MPs were briefed on the plans by Nadhim Zahawi, the vaccines minister, last week.

The disclosure comes ahead of the lifting of many Covid restrictions on Monday and as the Department of Health announced that every adult in the UK had now been offered a first dose of a vaccine – ahead of Boris Johnson’s target date of July 19. 

More than two-thirds (68 per cent) of adults have now received two doses. Officials said that every adult now had the opportunity to have both by mid-September.

How many people have been vaccinated?

The NHS is now preparing to roll out the vaccine imminently to 12 to 15-year-olds with underlying health conditions and those living with vulnerable adults.

They will be offered the Pfizer-BioNTech vaccine, which was approved for use in children aged 12 to 15 by the Medicines and Healthcare products Regulatory Agency last month after a "rigorous review".

On Saturday, Prof Sarah Gilbert, one of the scientists behind the Oxford-AstraZeneca vaccine said the benefits of vaccinating children were "much lower and poorer" than inoculating adults. 

She added: "With still a limited number of doses available to vaccinate the world, we should be use those doses for healthcare workers and for older individuals in countries that don’t yet have a vaccine." 

The UK decision is understood to have been made based on a "risk-benefit" analysis based on protecting children rather than a calculation taking into account excess supplies that the country could ship for use in adults abroad.

Teenagers aged 16 who are deemed vulnerable to Covid are already eligible for vaccines as part of group six of the vaccine rollout, which applies to adults aged 16 to 65 in an "at-risk group".

Those aged 16-65 deemed to be at risk include patients with blood cancer, diabetes, severe asthma, kidney disease and lowered immunity due to disease or treatment.

An NHS spokesman said: "Since the start of the NHS Covid vaccination programme, the biggest and most successful in NHS history, the NHS has followed JCVI guidance on delivering vaccinations to the population in England.

"If the JCVI updates its guidance, the NHS will act swiftly to reflect any changes and will continue to deliver Covid jabs to those eligible as quickly as possible, as it has done after previous updates."