The JCVI is currently reviewing the new risk data ahead of the rollout of vaccination to the under-40s.
But the several requests, MHRA was not able to say what the new risk level for the under-40s would be.
On April 7, deputy chief medical officer Jonathan Van-Tam presented data showing that when Covid is low in the community, the risk of a young person catching Covid and getting seriously ill becomes so small that it is even smaller than the risks from vaccination.
MRHA chief executive Dr June Raine, has said the "risk remains extremely small" despite "evidence firming" up of links between jabs and blood clots.
Out of the 79 cases reported in the UK, 51 women and 28 men suffered with clotting issues - all from the first dose.
She said anyone who has already had a first dose of AstraZeneca should still get their second, unless they suffered with clotting issues.
“It is still vitally important that people come forward for their vaccination when invited to do so,” she said.
The MHRA previously stressed the risk was “very small” and the benefits of the vaccines against Covid outweigh any risks”.
It come as the European Medicines Agency has said AstraZeneca coronavirus vaccine provides a "significant benefit" in avoiding hospital admission across all age groups.
Overall, the benefits of the jab continue to outweigh the risks of rare blood clots, and benefits increase in older age groups and in areas with higher levels of coronavirus infection, the regulator said.
The EMA said its human medicines committee had analysed available data on the vaccine to put the risk of rare blood clots into context of benefits for different age groups and different rates of infection.
Dr Peter Arlett, the EMA's head of data analytics and methods task force, said the AstraZeneca vaccine is "highly effective at preventing infection, and therefore hospitalisation and death".
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