This Thursday, the Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA) plans to rule on the safety of one of the four vaccines approved in Europe, the one developed by the AstraZeneca company and the University of Oxford.
It will do so after more than 10 European countries -including Spain- decided in recent days to suspend vaccination with the drug from the Anglo-Norwegian company, a medicine authorized by the EMA itself, by the World Health Organization and by the UK drug regulatory agency, where vaccination continues.
But it will also do so after an event that has jumped into the media. greatly disturbing the target population of this vaccine, whose first dose many teachers or policemen have already taken, to name just two essential professions to which the drug has been assigned.
On the morning of this Wednesday, the Ministry of Health reported that the day before they had registered two new reports of suspected adverse reactions in the FEDRA database of the Spanish Pharmacovigilance System coordinated by the Spanish Agency for Medicines and Health Products (AEMPS).
This is a person with a ischemic stroke with hemorrhagic transformation that, “unfortunately, it had a fatal outcome” and a person with abdominal venous thrombosis. Both had been vaccinated with the drug whose administration has been suspended in the last 16 days.
These two cases are added to the case registered in FEDRA on March 15, of a person – his sex or age has not been specified – who suffered a cerebral venous thrombosis also in the days after vaccine administration.
But does this mean that the profes not sure? No, even if it really was the cause of the thrombosis, something that is not proven and is studying the PRAC, Pharmacovigilance Risk Assessment Committee of the EMA, is reviewing all cases of thromboembolic events and other conditions related to blood clots, reported after vaccination with the AstraZeneca vaccine .
As explained by Juan José Carreras Martínez, head of Pharmacovigilance in the Vaccine Research Area of Fisabio, in The Conversation, when such a large number of people are vaccinated in a short period of time, including groups of patients at risk of certain diseases, it is Unavoidable to observe a high number of adverse events without this meaning that they are due to the vaccine.
Keep in mind that many of these events would appear in the same way if the person had not received the vaccine. Therefore, this information must be carefully analyzed to differentiate medical problems associated with the vaccine from those that would still have occurred even if the person had not been vaccinated.
In fact, and according to the Ministry of Health itself, in Spain the first dose of the vaccine has been administered – there has not been time to put the second, which must be administered after three months – to 975,661 people. Of them, three have suffered the problem that all the media covers.
To perform this analysis, cases are documented as much as possible and certain data are valued. For example, the time sequence, the time elapsed between the administration of the vaccine and the appearance of symptoms, medical history, concomitant medication, risk factors, patient evolution, etc., in addition to laboratory and imaging tests.
In cases where there is a fatal outcome, it is assessed additional information such as that from autopsies, death certificates and relevant medical records. All this information allows us to know if there are alternative causes that may have caused the medical event.
The first thing to do is distinguish whether these thromboses are adverse events or adverse reactions. As explained by the AEMPS, an adverse event is any undesirable event experienced by a patient, regardless of whether or not the drug administered is suspected. An example of an adverse event is a patient who suffers a traffic accident while on a specific drug treatment. On the other hand, an adverse reaction (ADR) is any undesirable event that has happened with the patient while he was using a medicine and there is a suspicion that it is caused by the medicine.
Currently, with the available data, there is no evidence that the AstraZeneca vaccine is the cause of the thromboembolic events. Therefore, the PRAC collects that the benefits of the vaccine continue to outweigh its risks and it can continue to be administered pending evaluation of all reported bleeding disorder events.
Once the review is complete, the PRAC will make the recommendations necessary to minimize risks and protect the health of patients, if necessary.
But even if the PRAC concluded that the administration of the vaccine is behind the three thromboembolic events detected in Spain in vaccinated people (around 30 throughout the continent) this should not lead to vaccine stoppage.
As the Ministry of Health also mentions in its last communication, measures can be established that try to minimize the risk. An example of them would be to identify the factors that predispose to the appearance of this type of thrombosis and the limitation of the use of the vaccine when this risk factor occurs.
In any case, what is proven is that the Oxford University vaccine is effective in preventing Covid-19 and that, today and with at least 70,000 deaths in Spain, reducing infections should be a priority. The effectiveness of pharmacovigilance will allow Europe to resume vaccination, or at least that is what all the data seem to indicate. With or without new limitations.