Covid vaccine and adverse reactions: Pfizer surpasses AstraZeneca in number of reports

Covid vaccine and adverse reactions: Pfizer surpasses AstraZeneca in number of reports
Covid vaccine and adverse reactions: Pfizer surpasses AstraZeneca in number of reports
Vaccines and adverse reactions: how many cases are there in Italy and what are the side effects? Aifa’s third pharmacovigilance report on anti-Covid vaccines provides an answer. Out of 9 million inoculated doses, about 46 thousand reactions were reported: of these only 7.1% were serious. And in the “ranking” of vaccines Pfizer / BioNTech surpasses AstraZeneca for reported events.

Below are the details of the data relating to the period 27 December 2020 – 26 March 2021 illustrated by the report.

How much and when do adverse reactions occur

“There were 46,237 reports of adverse reactions, out of a total of 9,068,349 doses administered (reporting rate of 510 per 100 thousand doses), registered in the National Pharmacovigilance Network between 27 December 2020 and 26 March 2021 for the three vaccines in use in the current vaccination campaign ”, explains the Italian Medicines Agency in the report.

The reported events arise mainly “on the same day of vaccination or the next day (87% of cases)”, specifies AIFA. For all vaccines, the most reported adverse events are “fever, headache, muscle or joint pain, pain at the injection site, chills and nausea, in line with the known information on vaccines used so far in Italy”, add the experts.

The number of serious reactions reported

Of the 46,337 adverse reactions “92.7% refer to non-serious events, which resolve completely, such as pain at the injection site, fever, asthenia / fatigue, muscle aches”. Serious reports correspond to “7.1% of the total, with a rate of 36 serious events per 100 thousand doses administered, regardless of the type of vaccine, the dose (first or second) and the possible causal role of vaccination”.

The “ranking” of vaccines

“Most of the reports are related to the Comirnaty vaccine, or Pfizer / BioNTech (81%), so far the most used in the vaccination campaign (68% of the doses administered), with an increase in reports for the Vaxzevria vaccine, already known as AstraZeneca (17%) – underlines the AIFA report – following the increase in the use of this vaccine (27% of the doses administered). The reports relating to the Moderna vaccine instead represent 2% of the total and are proportional to the more limited number of doses administered (5%) ”.

Deaths and causation

In the period from December 27, 2020 to March 26, 2021, 100 deaths were reported in Italy temporally related to anti-Covid vaccinations with one of the three vaccines available so far, namely those of Pfizer, Moderna and AstraZeneca. However, only for one of these cases has a direct correlation with immunization been proven at the moment. In this period, 76 deaths were reported after vaccination with Pfizer, 12 with the Moderna vaccine and 12 with the AstraZeneca one. The general reporting rate for deaths is 1.1 cases for every 100,000 vaccine doses administered. In particular, for the Pfizer-Comirnaty vaccine it is equal to 1.1 per 100 thousand doses, for Moderna it is 2.8 and for the Vaxzevria vaccine by AstraZeneca it is equal to 0.7. The distribution by type of vaccine, Aifa underlines, “depends in part on the different number of doses administered for the various vaccines in the various age groups”.

The detailed assessments of the cases, the Drug Agency also warns, “suggest the absence of responsibility for the vaccine in most of these, as they are often subjects with existing or previous pathologies. Consequently, both the evaluation of the cause of death and the attribution of the causal link are complex “. For now, 64% of reports with a fatal outcome (equal to 64 out of 100 reported cases) have been evaluated and 36% not yet. Compared to the total number of reports with a fatal outcome, the causal link was not correlated in 38% of cases, indeterminate in 22% and unclassifiable in 3%. The causal link “is correlated in a single report, relating to a 79-year-old man” with previous pathologies and vaccinated with an mRNA vaccine.

Thromboembolic events

A specific part of the report is dedicated to thromboembolic events after the administration of the Vaxzevria vaccine, or AstraZeneca. There have been, within 2 weeks of vaccination, explains Aifa, “very rare cases of thrombi associated with low levels of platelets in the blood”. Out of a total of 62 cases included in the European Eudravigilance network, 7 cases (with 2 deaths) of intracranial venous sinus thrombosis and 4 cases (with 2 deaths) of thrombosis of several blood vessels in an atypical site out of the 24 inserted were reported. in the same period in the EU network.

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