How do you know if a vaccine is causing an adverse event?

It is absolutely not certain that there is a cause-effect relationship between an adverse event following administration and a vaccine. For that of AstraZeneca, for now the link is only temporal, while the investigations continue

(Image: Unsplash) Concern and fears continue to grow, after other deaths - reported last weekend - of people to whom it had been administered the anti-Covid vaccine developed by AstraZeneca. In Italy, for example, another batch of the vaccine was recently suspended in Piedmont after the death of a teacher following administration. And while the regulatory bodies' investigations continue, so far there is no indication of a cause-and-effect link. A recent note from the Italian Medicines Agency (Aifa), in fact, highlights how the alarm about the safety of the AstraZeneca vaccine is unjustified: the link between deaths and vaccine, it says, is only temporal, and no causality has been demonstrated between the two events.

But how do you check if an adverse event is caused by a drug or a vaccine? The task is by no means simple and takes time. First of all, you need to know what the difference is between an adverse event and an adverse reaction. In the first case, an adverse event following immunization (Aefi) means any unfavorable episode that occurs after the administration of a vaccine, but which is not necessarily caused by its administration. An adverse reaction, on the other hand, is a noxious response to a vaccine for which a cause-and-effect relationship can be established. To distinguish event and reaction, therefore, it is necessary to evaluate whether it is possible to trace a cause linked to the drug. "It has been observed that following the introduction of a new vaccine, reports of adverse events often increase, probably due to greater attention from both health professionals and citizens," they specify from AIFA. "Collecting and analyzing all these reports serves to better understand the benefit / risk ratio of the vaccine".

To do this, we resort to the so-called pharmacovigilance, that is the set of activities that make it possible to collect all the safety data and information available on the use of medicines, which in turn is based on the National Network of pharmacovigilance, which collects, manages and analyzes reports of suspected adverse reactions made by doctors, health professionals and citizens. When several reports, thoroughly assessed by the AIFA and by the Regional Pharmacovigilance Centers, converge on the same type of phenomenon, then we start talking about a signal, which highlights a possible cause-effect relationship between the adverse event and the vaccine, up to that point. unknown or poorly documented moment. Subsequently, after having identified a signal, an in-depth evaluation at European level follows, with the involvement therefore of the EMA and more precisely of the Prac, the Pharmacovigilance Risk Assessment Committee, in which on the basis of elements and evidence it determines whether it can there is a causal link with the vaccine. In detail, we use the European database EudraVigilance, managed by the EMA, and subsequently the Vigibase, the world database of the World Health Organization (WHO), so that all reports of suspected adverse reactions are available to all authorities and from the scientific community.

From here, therefore, after a series of in-depth scientific evaluations on the available data (reports, clinical and epidemiological studies, scientific literature and reports from pharmaceutical companies), it will be possible to reach various conclusions , for example from the fact that the benefit / risk ratio of the vaccine remains unchanged, or that the risks outweigh the benefits and therefore the authorization of the vaccination must be suspended and the product withdrawn. A relationship between benefit and risk offered by the AstraZeneca vaccine is still valid. The EMA, in fact, specified that "the benefits of the vaccine continue to outweigh the risks and its administration can continue, while investigations into thrombosis continue". Furthermore, the information available so far indicates that the number of thromboembolic events in vaccinated people is not higher than that observed in the general population.


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Coronavirus Vaccines vaccine AstraZeneca-Oxford Coronavirus vaccine globalData.fldTopic = "Coronavirus, Vaccines , AstraZeneca-Oxford vaccine, Coronavirus vaccine "

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