Britain should not give the Oxford / AstraZeneca COVID-19 vaccine to under-30s when possible, the UK Joint Committee on Vaccination and Immunization (JCVI) said on Wednesday, due to a very rare side effect of blood clots in the brain.

Wei Shen Lim, COVID-19 Chairman for JCVI, said based on the data and evidence available, the committee indicated that it is best for adults under the age of 30 without underlying conditions to be offered an alternative to the AstraZeneca vaccine, if applicable.

He said that for younger people, where the risks of hospitalization were much lower, the risk / benefit calculation of the Oxford / AstraZeneca vaccine meant other vaccines were better.

“We do not advise stopping all vaccination for an individual of any age group. We advise a preference for one vaccine over another vaccine for a particular age group, really out of caution, rather than because we have serious security concerns, ”Lim said at a briefing.

He said people should continue to receive a second dose of the AstraZeneca vaccine if they had received a first dose.

It came after the UK medicine regulator MHRA identified a possible side effect of the COVID-19 vaccine developed by the University of Oxford and AstraZeneca involving rare brain blood clotting.

Managing Director June Raine said the benefits of the shot outweighed the risks for the vast majority, echoing an update from the European medicines regulator also made on Wednesday.

European and UK drug regulators have both previously said there is no increased risk of blood clots in general from the vaccine developed by Oxford and AstraZeneca.

However, the two investigated a small number of reports of brain blood clots, known as cerebral venous sinus thrombosis (CVST), which have occurred in association with abnormally low blood platelet levels after people were given the vaccine. .

Deputy Chief Medical Officer Jonathan Van-Tam said the move would only have a negligible impact on the pace of vaccine rollout in Britain.

Moderna’s fire deployment began on Wednesday, while Britain also deploys Pfizer’s vaccine