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How to catch rare arterial clots before a stroke? UK study on AstraZeneca shots gives clue

Scientists have reported for the first time details of stroke incidents caused by blood clots in arteries in three adults who received the AstraZeneca vaccine in the UK.

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New Delhi: Prolonged headaches, confusion, difficulty in speech and loss of vision two weeks after getting the vaccine — these are some of the symptoms that adults, who received the Oxford-AstraZeneca Covid-19 vaccine in the UK, experienced before being diagnosed with stroke caused by blood clots in the arteries.

Scientists have now reported the details of these extremely rare stroke incidents for the first time.

In a letter published in the Journal of Neurology Neurosurgery and Psychiatry Tuesday, researchers from University College London have detailed three cases of strokes caused due to blockages in the arteries after vaccination.

While rare cases of blood clots have previously been reported after administration of the AstraZeneca vaccine, those affected veins — more specifically veins in the brain.

But clots in the arteries — also known as arterial thrombosis — are the most common cause of stroke. This form of stroke, known as ischaemic stroke, hasn’t been previously seen as linked to the AstraZeneca vaccine.

While cases of strokes after vaccinations are extremely rare, such reports highlight the need for those receiving the vaccine in India, licensed as Covishield, to be aware of symptoms to look out for, up to two weeks after receiving the jab.


Also read: Sputnik V makers agree to supply Covid vaccine to Delhi, says CM Arvind Kejriwal


The cases

According to the letter, the first patient, a 35-year-old woman, experienced a headache on the right side and around her eyes six days after getting the vaccine. Five days later she awoke feeling drowsy and with weakness to her left face, arm and leg.

The doctors found a blocked artery and blood clots in a vein. She underwent brain surgery to reduce the pressure in her skull, plasma removal and replacement, and received the anti-clotting drug fondaparinux. However, the patient could not be saved.

The second patient, also a woman in her late 30s, experienced headache, confusion, weakness in her left arm and loss of vision on the left side 12 days after having received the vaccine.

Imaging showed blockages in several blood vessels including arteries that supply blood to the brain and arteries supplying the heart and lungs. Her platelet count increased following plasma removal and replacement, and intravenous corticosteroids. She was then given fondaparinux, and her condition improved.

The third patient, a man in his early 40s, experienced symptoms three weeks after receiving his vaccination, with problems speaking and understanding language. The team found a clot in an artery, but there was no evidence of clots in veins. He received a platelet and plasma transfusion, and fondaparinux, and remains stable.


Also read: Traumatised, burnt out & depressed — the silent crisis of Indian doctors in the second wave


What the scientists suggest

In addition to cerebral venous thrombosis (stroke due to blood clots in veins), vaccines can also lead to clots that block arteries supplying the brain, causing ischaemic stroke, researchers suggest.

Young patients with ischaemic stroke after receiving the AstraZeneca vaccine should urgently be evaluated with laboratory tests, including platelet count and anti-PF4 antibodies.

PF4 (antibodies to platelet factor 4) are proteins that help form clots.

Such patients need to be looked after by a multidisciplinary team, involving specialists in haematology, neurology, stroke, neurosurgery and neuroradiology, for rapid access to treatments.

‘Stroke much more common with Covid itself’

In a linked commentary, Hugh S. Markus, a professor at the Cambridge University, cautioned that though ischaemic stroke can follow Covid vaccination, the condition is much more common with the infection itself.

“During the current period of covid vaccination, a high index of suspicion is required to identify thrombotic episodes following vaccination,” Markus wrote.

“However, it is important to remember that these side-effects are rare, and much less common than both cerebral venous thrombosis and ischaemic stroke associated with Covid-19 infection itself.”

In a study conducted in Denmark and Norway, researchers found that for every 100,000 vaccinations, there may be 11 extra incidents of blood clots. However, this study too reiterated that the benefits of the vaccine far outweigh the risks.

(Edited by Amit Upadhyaya)


Also read: SII begins manufacturing, stockpiling 2nd Covid vaccine Covovax after Modi govt nod


 

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