What have the regulators said?

A review by EMA safety committee concluded on Apr 7 that “unusual blood clots with low blood platelets should be listed as very rare side effects” of the AstraZeneca vaccine.

Emer Cooke, executive director of the EMA, said: “The risk of mortality from Covid is much greater than risk of mortality from these side effects.”

The MHRA said there were still huge benefits of the vaccine in preventing Covid-19 and serious disease but added that due to a very small number of blood clots in younger people, those under the age of 30 will be offered Pfizer or Moderna jabs instead.

Dr June Raine, MHRA chief executive, added: “Anyone who has symptoms four days after vaccination or more should seek prompt medical advice – a new onset of a severe or persistent headache or blurred vision, shortness of breath, chest pain, leg swelling, persistent abdominal pain or indeed unusual skin bruising or pin-point spots beyond the injection site.”

How have other countries reacted?

Germany, the Netherlands, Sweden and Canada have restricted the use of the AstraZeneca vaccine in younger people. Italy and Spain have stopped the use of the  jab in the under-60s.

It comes as Denmark announced on Apr 14 it would stop administering Oxford/AstraZeneca’s Covid-19 vaccine following its possible link to very rare cases of blood clots, several Danish media outlets reported, citing unnamed sources.

The decision, which would remove the shot from Denmark’s vaccination scheme, could delay the country’s vaccine rollout by up to four weeks, based on previous statements by health bodies.

France has said under 55s who have had a first AstraZeneca dose should take a different vaccine for the second. Olivier Véran, the country’s health minister, said the new advice will be that the Moderna and Pfizer vaccines should be used for their second dose.

While Spain will study the effects of mixing different coronavirus vaccines, government researchers said on Apr 19, responding to shifting guidelines on the safety of the AstraZeneca’s shot.

Also, Australia has doubled its order of the Pfizer Covid-19 vaccine, as the country races to overhaul its inoculation plan over concerns about the risks of blood clots with the AstraZeneca vaccine.

What has AstraZeneca said?

In March of this year, AstraZeneca said it was analysing its database to understand “whether these very rare cases of blood clots associated with thrombocytopenia (low blood platelet count) occur any more commonly than would be expected naturally in a population of millions of people”.

Meanwhile on Apr 6, a trial of the Oxford/AstraZeneca vaccine on children was paused, but the scientists involved said there were no safety concerns with the trial itself and they were waiting for further information from the MHRA.

In response to these concerns, an Oxford University study examined the incidence of blood clotting on the brain in coronavirus patients and AstraZeneca recipients, finding that the occurrence of brain clots from coronavirus was eight times greater the risk presented by the AstraZeneca jab.

Sir John Bell, Oxford University’s Professor of Medicine, has stated that he expects all vaccines to have “some background level of clotting issues”. Bell went on to say that the data on this issue was still being collected for further study.

What are the experts saying?

Scientists in the UK have said urgent research is needed to understand more about the risk of these rare blood clots.

David Werring, professor of clinical neurology at the UCL Institute of Neurology, said: “The EMA and MHRA statements are helpful in providing further clarity about the very rare blood clots with low blood platelet counts – mainly in the brain (cerebral venous sinus thrombosis) but also in other parts of the body – that have occurred after the AstraZeneca vaccine.

“Both the EMA and MHRA emphasise that the overall benefit of the vaccine in preventing illness, hospitalisation and death from Covid-19 clearly outweighs the risks of this rare potential complication; thus, vaccination programmes should continue as planned.

“We still urgently need more research to first understand which individuals are at highest risk of these unusual blood clots in the brain, which although very rare, can often be serious or fatal.”

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