MHRA Chief Executive Dr June Raine (Photo: Peter Summers/Getty Images)

The Medicines and Healthcare products Regulatory Agency (MHRA) today (April 7) said it has identified a possible side-effect from the Covid-19 vaccine developed by Oxford University and AstraZeneca involving rare brain blood clotting.

The MHRA’s scientific review of the UK reports of extremely rare and unlikely to occur specific blood clots with lowered platelets has concluded that the evidence of a link with AstraZeneca vaccine is stronger, but more work is still needed.

Up to and including March 31, 2021, the MHRA had received 79 UK reports of blood clotting cases alongside low levels of platelets following the use of the vaccine.

The data suggests that there is a slightly higher incidence reported in the younger adult age groups and the MHRA advises that this evolving evidence should be taken into account when considering the use of the vaccine.

The medicines regulator is now issuing updated guidance for healthcare professionals on how to minimise risks, as well as further advice on symptoms for vaccine recipients to look out for four or more days after vaccination.

“The MHRA has undertaken a thorough review into UK reports of a very rare and unlikely to occur specific type of blood clot in the brain, known as cerebral venous sinus thrombosis (CVST) occurring together with low levels of platelets (thrombocytopenia) following vaccination with the Covid-19 Vaccine AstraZeneca,” the health regulator said.

The regulator is also considering other blood clotting cases (thromboembolic events) alongside low platelet levels.

These reports have been analysed by the government’s independent advisory body, the Commission on Human Medicines (CHM) and its Covid-19 Vaccines Benefit Risk Expert Working Group, which includes lay representatives and advice from leading haematologists.

“As a precaution, administration of Covid-19 Vaccine AstraZeneca in people of any age who are at higher risk of blood clots because of their medical condition should be considered only if benefits from the protection from Covid-19 infection outweighs potential risks,” the MHRA said in its latest update.

“Anyone who experienced cerebral or other major blood clots occurring with low levels of platelets after their first vaccine dose of Covid-19 Vaccine AstraZeneca should not have their second dose. Anyone who did not have these side effects should come forward for their second dose when invited.”

MHRA added that pregnant women should discuss with their healthcare professional whether the benefits of having the vaccine outweigh the risks for them as pregnancy predisposes to thrombosis.

Dr June Raine, MHRA Chief Executive, said: “The public’s safety is always at the forefront of our minds and we take every report of a suspected side effect very seriously indeed. We thoroughly analyse each and every report as we receive it and although the number of reports of CVST and other thromboembolic events has increased over the last week, so has the overall number of vaccinations administered, therefore these blood clots remain extremely rare and unlikely to occur.

“We ask anyone who suspects they have experienced a side effect linked with their Covid-19 vaccine to report it to the Coronavirus Yellow Card website.”

JCVI asks to stop administering vaccine to under 30s

Meanwhile, Britain’s Joint Committee on Vaccination and Immunisation (JCVI) said on Wednesday that the country should not give Oxford University/AstraZeneca’s vaccine to under 30s where possible due to the very rare side effect of blood clots in the brain.

Wei Shen Lim, Covid-19 Chair for JCVI, 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.

“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 at a briefing.

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

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