A comparison of the serious adverse effects of the AstraZeneca vaccine and the Pfizer-BioNTech vaccine

A comparison of the serious adverse effects of the AstraZeneca vaccine and the Pfizer-BioNTech vaccine

With the AstraZeneca vaccine there would be one case of thrombosis for every 9 thousand vaccinated. The frequency is greater than that indicated so far, equal to 1 case per 100 thousand, because the data considered are different. The study of the University of Perugia

(photo: Paul McManus via Pixabay) After the very rare cases of thrombosis following vaccination with AstraZeneca's Vaxzevria vaccine, to see even more clearly, a research group from the University of Perugia requested and analyzed updated data, provided by the European Medicines Agency (Ema), on adverse effects. The researchers compared the post-vaccine reactions from AstraZeneca with those from Pfizer-BioNTech vaccine: in general, it was reported that Vaxzevria would be associated with a much greater number of serious and non-serious effects. Furthermore, the serious events associated with thrombocytopenia and venous thrombus concern 1 in 9 thousand cases. The results are published in the Autoimmunity journal.

More cases with AstraZeneca

Researchers assessed the frequency of serious adverse events, related to thrombocytopenia, haemorrhages and thrombus, documented in the Ema European Eudravigilance database up to the date of 16 April 2021. The vaccines considered are Vaxzevria by AstraZeneca (Ae) and BNT162b2 (Bnt) by Pfizer-BioNTech, while the vaccine developed by Janssen of Johnson & Johnson is still under investigation. "The administration of ChA [Vaxzevria ed] was associated with a much higher frequency of severe adverse events", reads the text of the publication, "in each group of reaction Ae compared to what was found for the Bnt vaccine". In fact, the authors considered 19 groups - or categories - of reactions associated with vaccines, divided according to the organs affected. The possible causes of this mechanism are still being studied. The authors indicate that the node could be found in the way and in the quantity with which Vaxzevria produces the spike protein of the coronavirus.

How many cases

Taking for example the cases of thrombocytopenia, thrombus and hemorrhages we detect 33 out of a million episodes vaccinated with Pfizer-BioNTech and 151 out of a million with AstraZeneca. In general, the authors write, the frequency of these serious events is higher with Vaxzevria, while it is in line with that for the general population (how many events would normally occur, even without vaccination) in the case of Pfizer-BioNTech. In the case of the AstraZeneca vaccine, the frequency is about one in 9 thousand vaccinated. Serious adverse effects related to cerebral or splanchnic venous thrombosis and / or thrombocytopenia, the authors explain, are more frequent in young people aged 18 to 24 years and in women of childbearing age, with an incidence of 0.5 cases. every 10 thousand doses.

And that's not all. Research shows that serious adverse events from Pfizer-BioNTech's vaccine are even lower than expected and predicted. This observation, the authors explain, suggests that the adverse effects of the anti-Covid vaccines could be underestimated and that those associated with Vaxzevria could be even 2-4 times greater than those reported above.

If i the accounts do not add up

"Our data regarding thrombocytopenia and blood clots are in disagreement with those reported by the EMA, equal to one case per 100 thousand doses", reads again on Autoimmunity. But how can this discrepancy be explained? The topic is certainly complex and very technical, but in general the researchers from Perugia considered a broader picture of pathologies. What we read is that they did not consider Cvt / Svt thrombosis only if in the presence of thrombocytopenia, as has been the case so far by Ema. Instead, they included cases of thrombosis both in the presence and absence of thrombocytopenia and also thrombocytopenia alone.

The study also hypothesizes that the number of adverse effects caused by the AstraZeneca vaccine is similar to that of Johnson & Johnson vaccine, but this is an aspect that is still being investigated and to be demonstrated.

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Coronavirus Thrombosis vaccine AstraZeneca-Oxford vaccine Johnson & Johnson Vaccine Pfizer BioNTech globalData.fldTopic = "Coronavirus, Thrombosis, AstraZeneca-Oxford vaccine, Johnson & Johnson vaccine, Pfizer BioNTech vaccine"

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