The UK has received five reports of a specific brain blood clot in people who have received the AstraZeneca coronavirus vaccine, though no causal link has been made with the jab.
The five people were men aged 19 to 59 who experienced a clot together with low blood platelet count. One of the five has since died.
The Medicines and Healthcare products Regulatory Agency (MHRA) said that use of the vaccine should continue while the five reports were investigated.
“The available evidence does not suggest that blood clots in veins (venous thromboembolism) are caused by Covid-19 Vaccine AstraZeneca,” the agency said.
“A further, detailed review into five UK reports of a very rare and specific type of blood clot in the cerebral veins (sinus vein thrombosis) occurring together with lowered platelets (thrombocytopenia) is ongoing.”
'Extremely rare'
The MHRA stressed the events were “extremely rare” and there was a possibility they could have been caused by Covid-19 itself.
It said the cases represented a less than one in a million chance of suffering this type of clot, while the risk of dying from Covid-19 aged 40 to 49 was one in 1,000.
The type of clot – cerebral venous sinus thrombosis (CVST) – prevents blood from draining out of the brain.
Concerns about reports of blood clots, along with low platelet levels, have led to European countries including Ireland to pause the rollout of the shot while the cases are investigated.
Britain has administed 11 million doses of AstraZeneca's vaccine.
