There have been a handful of rare reports of blood clotting in younger people, particularly younger women under the age of 55, following the AstraZeneca jab. The vaccine is not associated with an increase in the overall risk of blood clots in those who receive it, however. What’s more, health bodies are yet to establish a causal connection. Nonetheless, the risk to younger people is not entirely surprising, said Paul Hunter, medical microbiologist at the University of East Anglia.
Speaking to Sky News, he said: “It would not be surprising from what we know about cerebral venous sinus thrombosis (CVST) before Covid that it would be particularly younger people and particular younger women who would be more at risk than other age groups and genders within society.”
As he explained, CVST is a very uncommon disease – it was thought to be two to five cases per million people a year.
“It is still pretty rare and uncommon in people with vaccine but this is something that still needs to be looked at,” Professor Hunter added.
CVST occurs when a blood clot forms in the brain’s venous sinuses – the clot keeps blood from draining out of the brain.
The MHRA has said it has received 22 reports of CVST and eight reports of “other thrombosis events with low platelets [the cells involved in clotting]” following use of the Oxford-AstraZeneca jab.
It is important to put these numbers into perspective – this is out of a total of 18.1 million doses given up to and including 24 March.
Professor Hunter was also keep to emphasise the overwhelming benefits of receiving the AstraZeneca vaccine.
He did add that they may be a “preferred vaccine” by the time the campaign reaches younger people, however.
In light of the findings, a number of countries have taken the decision to restrict the rollout of the vaccine to younger people.
The Netherlands is the latest country to follow suit, announcing on Friday that it was suspending the AstraZeneca vaccine’s use for people under the age of 60.
The Dutch health ministry said the precautionary measure was taken after five reports of blood clots in combination with low platelet counts in women between the ages of 25 and 65.
It follows Germany’s decision to suspend routine use of the jab for people below the age of 60 due to fears over a link with blood clots.
It has reported 31 CVSTs and nine deaths out of 2.7 million people vaccinated.
Almost all the cases are reportedly in younger and middle-aged women.
The European Medicines Agency (EMA) conducted an investigation into the link but turned up no causal connection.
“Because these events are rare, and COVID-19 itself often causes blood clotting disorders in patients, it is difficult to estimate a background rate for these events in people who have not had the vaccine,” the EMA concluded.
The Committee was of the opinion that the vaccine’s proven efficacy in preventing hospitalisation and death from COVID-19 outweighs the extremely small likelihood of developing DIC or CVST
“However, in the light of its findings, patients should be aware of the remote possibility of such syndromes, and if symptoms suggestive of clotting problems occur patients should seek immediate medical attention and inform healthcare professionals of their recent vaccination,” the EMA advised.
“Steps are already being taken to update the product information for the vaccine to include more information on these risks.”