LONDON/BRUSSELS • Britain should not give the Oxford-AstraZeneca Covid-19 vaccine to under-30s where possible, Britain's Joint Committee on Vaccination and Immunisation has said, due to a very rare side effect of blood clots in the brain.

Professor Wei Shen Lim, Covid-19 chair for the committee, said that based on the available data and evidence, the committee has advised that it is preferable for adults aged under 30 with no underlying conditions to be offered an alternative to the AstraZeneca vaccine where available.

He said that for younger people, where the risks of hospitalisation were much lower, the risk/benefit calculation of the AstraZeneca shot meant other vaccines were preferable. "We are not advising a stop to any vaccination for any individual in any age group. We are advising a preference for one vaccine over another vaccine for a particular age group, really out of the utmost caution, rather than because we have any serious safety concerns," he said yesterday.

He added that people who had received a first dose of the AstraZeneca shot should continue to have a second dose.

The advice came after Britain's Medicines and Healthcare Products Regulatory Agency identified a possible side effect from the Covid-19 vaccine developed by Oxford University and AstraZeneca involving rare brain blood clotting.

The recommendation will have a negligible impact on the vaccine programme, England's deputy chief medical officer Jonathan Van-Tam said.

In its latest recommendation, the European Medicines Agency highlighted a possible link between the AstraZeneca vaccine and a rare type of blood clot in the brain. But it added that "unusual blood clots with low blood platelets should be listed as very rare side effects".

Safety concerns have prompted more than a dozen countries in recent weeks to suspend use of the vaccine, which has been given to tens of millions of people in Europe, after reports linking it to a brain blood clotting disorder in a few dozen recipients.

The European Medicines Agency's announcement is a fresh setback for the vaccine, which is sold at cost, for a few dollars a dose, and is by far the cheapest and most high-volume one launched so far. After extensive use in Britain and mainland Europe, it is set to be the mainstay of vaccination programmes in much of the developing world.

Experts say that, even if a causal link between the vaccine and blood clots is proved, the risks to the general population of getting a serious clot are vanishingly small compared with the risks from possible Covid-19 infection.

The European Medicines Agency and World Health Organisation have said the benefits of the vaccine outweigh the risks.

REUTERS, BLOOMBERG