The Joint Committee on Vaccination and Immunisation (JCVI) update extends its previous advice for all under-30s to be given an alternative jab, amid reports of “extremely rare” cases of blood clots associated with the vaccine, which is being produced in India as Covidshield.

While the JCVI reiterates that the benefits from the vaccine continue to outweigh the risks, younger age groups are believed at a higher risk from the rare blood clots.

“JCVI advises that, in addition to those aged under 30, unvaccinated adults aged 30 to 39 years who are not in a clinical priority group at higher risk of severe COVID-19 disease, should be preferentially offered an alternative to the AstraZeneca COVID-19 (AZD1222) vaccine, where possible and only where no substantial delay or barrier in access to vaccination would arise,” the JCVI advice reads.

“For those aged 18 to 29 years the precautionary advice for a vaccine preference is stronger, reflecting a gradient in the benefit-risk balance with age,” it notes.

Latest data from the Medicines and Healthcare products Regulatory Agency (MHRA) shows there have been 242 blood clots in combination with low platelets in more than 28 million people who had the Oxford/AstraZeneca vaccine up to the 28 April.

The risk of a clot is roughly one in 100,000 for people in their 40s, but rises to one in 60,000 for people in their 30s. Meanwhile, the risks of developing severe COVID-19 on contracting coronavirus also fall with age.

“The balance of benefits and risks is very favourable for older people, but is more finely balanced for younger people,'' explained Dr June Raine, the MHRA chief executive.

The alternative vaccines for the lower age groups on offer will include the Pfizer/BioNTech and Moderna jabs.

However, some under-40s may still be offered the Oxford/AstraZeneca vaccine if the supply flow so requires, in keeping with JCVI advice, to ensure no slowdown to the vaccination programme in an effort to avert a third wave of the pandemic in the country.

“The Oxford/AstraZeneca vaccine is safe, effective and has already saved thousands of lives in the UK and around the world. As the MHRA – the UK’s independent regulator – and the Joint Committee on Vaccination and Immunisation have said, the benefits of the vaccine far outweigh the risks for the vast majority of adults,” a UK government spokesperson said.

“More than 50 million vaccines overall have already been administered, and our current vaccine supply and rate of infection means we are able to take this precautionary step while remaining on track to achieve our target of offering a vaccine to all adults by the end of July,'' the spokesperson said.

''Everybody who has already had a first dose of the Oxford/AstraZeneca vaccine should receive a second dose of the same jab, irrespective of age, except for the very small number of people who experienced blood clots with low platelet counts following their first vaccination,” the spokesperson added.