Update: AstraZeneca and blood clots
An effort to close the communication loop.
Yesterday, the European Medicines Academy (EMA) met to review the evidence regarding AstraZeneca (AZ) vaccine and blood clots. They invited experts in blood disorders as well as members from the Medicines and Healthcare products Regulatory Agency.
What did they do?
The committee evaluated all blood clotting events (469 reports out of ~20 million vaccinated) in the UK and EU. They looked “in extreme detail” to two specific events:
CVST (Cerebral venous sinus thrombosis): A rare circumstance where clots are found in the vessels draining blood from the brain
DIC (Disseminated intravascular coagulation): Blood clots in multiple blood vessels
There were 18 cases of CVST and 7 cases of DIC, in which 9 people died. These events were among almost all women under the age of 55.
What did they conclude?
The number of blood clotting events (469) reported after vaccination, was lower than that expected in the general population. In other words, there is NO increase in overall risk of blood clots.
However, in younger people (<55 years) there remains concern, related in particular to CVST and DIC. For DIC, the committee expected <1 case among people under 50 within 14 days of receiving the vaccine. But 5 cases were reported. For CVST, the committee expected ~1 cases among this age group. But 12 were reported. This imbalance was not visible in the older population given the vaccine. “A causal link with the vaccine is not proven, but is possible and deserves further analysis.”
The benefits of the vaccine continue to outweigh the risk of side effects, even among those aged <55 years. We know that COVID19 causes blood clots. We know that the vaccine prevents hospitalization and death. And, we now know that there is a extremely small likelihood of developing DIC or CVST.
So, what’s going to happen?
From what I gather…
AZ will still be distributed;
EMA will continue to closely monitor reports of blood clotting disorders;
Studies have been initiated to provide more laboratory data as well as real-world evidence on why we may be seeing a link;
Sponsors will put a warning label re: blood clots on the AZ vaccine package leaflet.