Seven people have died of unusual blood clots after receiving the Oxford-AstraZeneca vaccine in the UK. A total of 30 out of 18 million people vaccinated as of March 24 had these clots.
The Medicines and Health Products Regulatory Agency says the benefits of the AstraZeneca vaccine continue to outweigh any risks.
However, concerns have led other countries, including Germany, France, the Netherlands and Canada, to restrict the use of the vaccine only to the elderly.
Data released by the MHRA on Friday showed 22 cases of cerebral venous sinus thrombosis (CVST) which is a type of blood clot in the brain.
These were accompanied by low levels of platelets, which help form blood clots, in the body. The MHRA also found other clotting problems alongside low platelet counts in eight people. The MHRA has confirmed that “Unfortunately seven died”.
Investigations are underway to determine whether the AstraZeneca vaccine is the cause of the very rare blood clots. Earlier this week, the European Medicines Agency said it was “Not proven, but it was possible”.
Two questions raise suspicion. The first is the unusual nature of the clots, including low levels of platelets and rare antibodies in the blood which have been linked to other bleeding disorders.
“This raises the possibility that the vaccine may be a causal factor in these rare and unusual cases of CVST, although we don’t know it yet, so more research is urgently needed.“Said Professor David Werring of the UCL Institute of Neurology. .
However, there is still some uncertainty as to the normal frequency of these clots. Estimates range from two cases per million people each year to almost 16 in a million normal cases and the coronavirus has been linked to abnormal clotting, which can make these clots more common.
Germany has reported 31 CVST and nine deaths out of the 2.7 million people vaccinated there, most of the cases in young or middle-aged women.