Because we have to stay calm about the AstraZeneca vaccine

Concern about the Astrazeneca vaccine is very high. Here's what we know about its safety, from pharmacovigilance data, and why you need to stay calm, but vigilant

(photo: Pixabay) Another shot. In addition to the already widespread skepticism in considering it a series B product, in these hours the concern about the AstraZeneca vaccine is at very high levels, after the announcement of several European countries to suspend the administration of the vaccine in general or as a precaution. the use of a specific batch (as happened in Italy) of the vaccines produced by this pharmaceutical company. And while investigations into adverse events, namely thromboembolytic events, observed after its administration continue, the EMA, the European Medicines Agency, has sent for calm, stressing that so far there is no causal link between the vaccine and these events and that is why the vaccine can continue to be administered.

We remind you that in recent days the Austrian authorities have suspended the use of a batch, the number Abv5300, after some cases of thrombosis have occurred (one fatal) following the administration of the AstraZeneca vaccine. And just yesterday in Italy too, the Italian Medicines Agency (Aifa) issued a note in which it suspended the use of another batch, the number Abv2856, throughout the national territory (560 thousand total doses, of which 250 thousand for Italy), in light of reports of serious adverse events (also fatal cases).

But we must be clear: there is a difference between adverse events, adverse reactions and side effects. Adverse events are adverse events that occur temporally after the administration of a vaccine, but which are not necessarily caused by the drug. Adverse reactions, on the other hand, are harmful and unexpected responses to a drug for which a causal relationship can actually be established with the intake. Finally, side effects or unwanted effects relate to a reaction to the drug which is not necessarily harmful, but which has been experienced in a number of people. It may therefore be a known effect and considered acceptable in the benefit-risk balance.

But what do we know so far about the safety of this vaccine, hence its known side effects? As we told you a few days ago, in general they occur more often in young people, or in the under 65s: the reason is a stronger immune system response, which leads to a greater probability of developing antibodies against the coronavirus. Serious adverse reactions caused by the AstraZeneca vaccine are very rare: their frequency is, in fact, less than one case in every 10,000 vaccinated.

On the other hand, mild or moderate side effects have a rather high frequency. In other words, it is more likely, after receiving the vaccine, to have a fever than not to have it and so for all other symptoms, such as arm pain at the injection site, headache, fatigue, muscle aches and so on. In detail, pain at the injection site is recorded in about 63% if it is pushed to the point of the arm and in 54% without touching it of the vaccinated. Fatigue, on the other hand, occurs in 53% of cases, headache in 52%, malaise and muscle pain in 44%, joint pain in 26% and nausea and vomiting in 21%. Fever (considered from 38 degrees) in about 8% of cases. Then there are the less frequent reactions, such as drowsiness, dizziness, a sense of inappetence, skin rashes and excessive sweating.

And then there is the whole mechanism of pharmacovigilance, which precisely serves to signal the effects adverse. This system, in simple terms, has the task of monitoring what happens after the administration of a vaccine. It is open to all, health professionals, patients, parents and citizens, who can send their reports by contributing to the monitoring of the safe use of vaccines and which are registered in the National Pharmacovigilance Network (Rnf). According to the latest Pharmacovigilance Report on anti-Covid vaccines, published by AIFA and which has a monthly frequency (updated as of February 26), the frequency of adverse reactions of anti-Covid vaccines, Pfizer, Moderna and AstraZeneca (for this last, there were still no injections of the second dose) seems to be in line with that observed in clinical studies and with the documentation submitted for the approval request by the pharmaceutical companies. In particular, nearly all reports, approximately 93%, concerned mild or moderate events. Serious reports, on the other hand, have recorded, regardless of vaccine and dose, a rate of 44 serious events per 100 thousand doses administered.

Returning to today and the discontinuation of the AstraZeneca vaccine batches, Ema is already examining all cases of thromboembolic events reported after vaccination, specifying however that so far, the number of these events in vaccinated people is not higher than that observed in the general population. As of 9 March, 22 cases of thromboembolic events have been reported among nearly 3 million vaccinated people in Europe. And the statistics, for now, do not create alarms: as the biologist Enrico Bucci explains, in fact, if of the 250 thousand doses in Italy only the three cases described had been observed, the frequency of these events would be about one in a hundred thousand, in line with the 22 cases out of 3 million before. Not only that: if we focus on thrombotic events and their frequency, in the phase 3 clinical trials of Johnson & Johnson's newly approved vaccine, 15 thromboembolytic events were observed in 14 people who received the vaccine and 10 events in those who had not been vaccinated. (and had received a placebo). As the expert points out, among those who received the placebo, 2 out of 10 thousand experienced serious thromboembolytic events immediately afterwards. "If this is the case with the placebo, it goes without saying that we shouldn't be surprised by the mere occurrence of such events."


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Topics

Coronavirus Italy Health vaccine AstraZeneca-Oxford Coronavirus vaccine globalData. fldTopic = "Coronavirus, Italy, Health, AstraZeneca-Oxford vaccine, Coronavirus vaccine"

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