London, The UK's vaccine advisory body has declined to grant approval for inoculating healthy children aged 12-15 years citing lack of sufficient evidence, and has also ceded authority on the decision to the country's top medical officers, according to media reports.

The decision by the Joint Committee on Vaccination and Immunisation (JCVI), the independent vaccine advisory group, was based on a concern over an extremely rare side effect of the Pfizer and Moderna vaccines which causes heart inflammation, and can lead to palpitations and chest pain, the BBC reported.

Data from the US, where millions of young teenagers have been vaccinated, suggests there are 60 cases of the heart condition for every million second doses given to 12 to 17-year-old boys (compared to eight in one million girls).

According to the JCVI, as children were at a low risk from the virus the jabs would offer only a marginal benefit and, therefore, there showed "insufficient" evidence to offer mass vaccination to this age group.

Although the vaccine advisers have been under huge pressure, they are "taking a precautionary approach", Prof Wei Shen Lim, chairman of Covid immunisation at JCVI was quoted as saying.

"The margin of benefit is considered too small to support universal Covid-19 vaccination for this age group at this time. The committee will continue to review safety data as they emerge," he added.

The JCVI also noted that the health benefits of jabs for younger teenagers when weighed against possible side-effects were not yet clear.

On Friday, in an unprecedented step, the JCVI passed the decision on to England's chief medical officer Professor Chris Whitty and his three counterparts from the UK's devolved administrations, the Financial Times reported.

The response from the medical officers is expected to come back "as soon as next week", the report said, citing people familiar with the process even as political pressure mounts to jab children over 12 as schools return from summer holidays.

The officers are expected to give the green light to a rollout, as Sajid Javid, UK Health Secretary has asked them to take into account "broader educational and societal impacts" than the JCVI's remit permits.

The new decision on a rollout of Covid shots to all 12-15 year olds will also have the involvement of senior leaders in clinical and public health.

"We will then consider the advice, building on the advice from the JCVI, before making a decision shortly," Sajid Javid, the UK Health Secretary was quoted as saying.

A group of 24 countries including France, Italy, Israel and Ireland have already offered the vaccine to all children in this age group