Is There A Risk of Blood Clotting with AstraZeneca?

The Medicines and Healthcare Products Regulatory Agency (MHRA) has said that at least 30 people in the UK have experienced unusual blood clots after they were injected with the Oxford-AstraZeneca vaccine.

The MHRA has advised the UK to continue the administration of Oxford-AstraZeneca, arguing that the benefits outweigh any risks, echoing the recommendations of the European Medicines Agency (EMA) and the World Health Organization (WHO).

According to a research by the BBC, however, with increasing reports of blood clots from different countries, especially in Europe where the vaccine is widely used, some countries like France, Germany and Canada are choosing to restrict who can receive the vaccine while others have suspended its administration altogether. Health safety regulators and scientists are trying to determine if the vaccine genuinely causes blood clots, and how much risk this can pose to vaccination programs.

Is There a Link Between the Vaccine and Blood Clots?

According to the European Medicines Agency EMA, it is “not proven, but is possible”. The agency has to determine whether the reported blood clots are a side effect of receiving the vaccine or a coincidence that would have occurred otherwise. This is a very tricky situation, especially when faced with rare events.

One important indicator to consider is incidence. Blood clotting is common and can be expected in certain persons for a variety of reasons at any time of any given day or week. If an individual received a vaccine and then develops a clot, this does not necessarily mean that the vaccine caused the clot. There are scientists who are sceptical, while others are getting increasingly convinced of the link between using the shot and developing blood clot.

To have a clearer understanding, scientists are taking a look at the specific type of clots reported. To begin with, cerebral venous sinus thromboses (CVST) is a rare type of blood clot that forms in the venous sinuses of the brain. However, while it is not difficult to determine whether a person has developed blood clot, this current situation is a little tricky, partly because the rate of CVST in the population is unclear in the first place.

According to the MHRA, of the 15.8 million people who have received at least one shot of the AstraZeneca vaccine in the UK, 30 cases of CVST or other thrombosis have been reported. These figures mean that there are around two cases per million reported incidents of one of these rare clots. “So, the absolute risk of CVST after this vaccine remains extremely low… and it is not clear if this is any higher than the usual expected incidence of CVST,” said Prof. David Werring from the UCL Institute of Neurology.

Prof. Werring also said that CVST usually affects around 5 to 15 persons per million each year in the UK, but added that those figures are relative due to the difficulty in diagnosing the condition.
Of more importance to scientists now is the nature of these blood clots. Recent research suggests that the clots developing after vaccination presents unusual features; while the affected patients are, indeed, experiencing blood clots, they also manifest symptoms of thrombocytopenia – a condition characterized by low blood platelet count that usually prevents clotting, according to the EMA and other health experts.

“This raises the possibility that the vaccine could be a causal factor in these rare and unusual cases of CVST, though we don’t know this yet, so more research is urgently needed,” Prof. Werring said.

Are the Blood Clots Fatal?

It is difficult to conclude on the fatality rates as the number of those who developed clots after receiving the vaccine is so small. In the UK, four of the 30 cases of CVST were fatal; in Germany, nine were.

According to experts in a draft study that is yet to be peer reviewed, the low blood platelet counts (heparin-induced thrombocytopenia) is “treatable if identified promptly”. While presenting the group’s findings to journalists this week, Andreas Greinacher from the University of Greifswald called what he believes is a reaction to receiving the shot a “vaccine induced prothrombotic immune thrombocytopenia”. Ultimately, they are calling on healthcare professionals to avoid administering heparin in patients who present blood clots if they have received the AstraZeneca vaccine, as this could worsen their condition.

Is the AstraZeneca Vaccine Safe?

There is no 100% safety guarantee when it comes to medicine; even the most brutal medical procedures like chemotherapy can be very valuable when used in the right circumstance. The crux of the matter is whether the benefits outweigh the risks.

The pandemic presents a major challenge in this case. Usually, medical experts adopt the “precautionary principle – a strategy used for decision-making when health professionals and patients lack evidence relating to the potential outcomes associated with various choices – to determine the level of medical risk before giving new medicine to a mass of people. But in a pandemic, delays in vaccinating means the loss of lives.

Based on data available in Germany alone, if one million people are vaccinated with the AstraZeneca vaccine, 12 persons are expected to develop blood clots and four are expected to die. On the other hand, if one million 60-year-olds contract coronavirus, about 20,000 of them would die of the virus; if one million 40-year-olds contract the virus, then around 1,000 are expected to die.

Without doubt, the benefits of receiving the vaccine increases with age, and countries like Canada and Germany have allowed the administration of the vaccine on older age groups. While we are still not completely on the clear as to the link between the AstraZeneca vaccine and blood clots, current data suggests that the benefits outweigh the risks. Over time, the decision to administer vaccinations will depend on which alternative vaccines are available and those who still need the vaccinations.

How We Can Help

At Medical Negligence Direct, we work with a panel of specialist medical negligence solicitors who have years of experience in successfully handling different type of medical negligence claims, including blood clot negligence. Contact us today on 0800 644 4240 to speak with one of our friendly solicitors and find out how we can help.

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