AstraZeneca vaccine against Covid and adverse events, chance or causality? The differences –

by time news

Aifa, the Italian drug agency, has blocked the use of a batch of AstraZeneca’s Covid vaccine, following the reporting of some serious adverse events, in temporal concomitance with the administration of doses of the vaccine. Aifa’s decision, relating to a single lot – from code ABV2856 – was taken as a precaution after two deaths in Italy due to events attributable to thrombosis and others under investigation.

The investigations

In its statement, Aifa underlines the temporal concomitance, writes that at the moment no causal link has been established between the administration of the vaccine and these events and explains that it is carrying out all the necessary checks, acquiring clinical documentation in close collaboration with the NAS and the competent authorities. In other words, after the reporting of two concomitant events, vaccination and deaths reported in Sicily, the authorities in charge are trying to exclude or not the most important link, that of cause and effect: it may have been the administration of the vaccine (or of a lot of it) to determine circulatory problems attributable to thrombosis, or they are related circumstances without any direct relationship?

Time coincidence or causal link?

It is necessary to establish clearly and with scientific criteria the casualit or causalit: a difference that, as in the two Italian words, seems subtle but substantial. There correlation indicates the concomitant increase (or decrease) of two variables: increase in vaccinated people, increase in adverse events, but it does not express a causal link, it can be just random because there is the possibility of a coincidence in time. Investigations must examine the medical records of those affected and possibly (in the case of deaths) have autopsies performed and relate the single event with vaccination. This is the only way to highlight whether there are other links between the events, in particular, that of cause and effect.

Pharmacovigilance and data

The pharmacovigilance serves this: a direct surveillance by AIFA that examines the so-called adverse events for each type of drug approved (or in the process of being approved) and studies correlations to highlight causal relationships. an ongoing process. Aifa has just published the second Covid-19 Vaccine Surveillance Report (data from 12/27/2020 to 2/26/2021), which confirms the high safety profile of vaccines currently used in Italy (and in Europe ). From the end of December (administration of the first vaccines) to the end of February there have been 729 records found of adverse events per 100 thousand doses administered, regardless of the type of vaccine. For AstraZeneca, the majority of events involved fever, chills, asthenia / fatigue and injection site pain. 90% of these reports are classified as non-serious. This is followed by widespread muscle and joint pain, headache, nausea and vomiting. Most of the 79 reports of serious adverse events refer to high fever, tremor, dizziness, excessive sweating, somnolence, difficulty in breathing, generalized pain. As of February 26, 2021, they have been inserted for Italy 40 reports with death results (also concerning the other two vaccines, Pfizer and Moderna), but case assessments indicate the absence of responsibility for the vaccine, because they are people who had previous pathologies and who took several drugs at the same time. The mean age of fatal cases was 86 years. Cardiovascular-related death is very often in patients with underlying cardiovascular disease. These are the official figures so far, but the study continues.

Apparently healthy victims

In the case of the most recent deaths reported after the administration of AstraZeneca, the absence of previous pathologies is striking (which may only be apparent) and the young age of the people involved (a soldier serving in Augusta, Stefano Patern, aged 43, and Davide Villa, a police officer aged 50). We must not forget, however, that unfortunately there are every day in Italy hundreds of deaths apparently inexplicable, even of young and healthy people, and it is only known when it comes to faces known to the general public or causes of death in the public interest. The example can be that of the death of the football player Davide Astori, due to a never diagnosed heart disease. It follows that each case must be evaluated, but not only.

Clinical studies

As we have learned in the case of vaccines (but it applies to every drug) the vigilance is not triggered now, but before approval, during clinical studies which were the long but necessary phase to get the go-ahead from the regulatory bodies. Studies evaluate, in addition to efficacy, too the safety of vaccine candidates, comparing the adverse events that occur in the group of vaccinated people with the adverse events that occur in the group of people who received a placebo (in the case of AstraZeneca, an injection of physiological). Well, EMA, the European Medicines Agency, reported that the number of thromboembolic events in vaccinated people no higher than that observed in the rest of the population.
In the Phase 3 studies (preluding to authorization) officially published by AstraZeneca on Lancet, involving 23,848 participants, there were 175 serious adverse events in 168 subjects: 84 were in the vaccinated group and 91 in the placebo control group. In addition to these assessments, the EMA has received other data upon approval and the analyzes are continuing.

AstraZeneca’s answer

This shows that circulatory problems attributable to thrombosis occurs regardless of vaccination, you have to understand if their frequency increases in conjunction with vaccination and after, if you notice this increase compared to the normal figure, examine the individual cases for highlight (or discard) the cause-effect link. Until these steps have been completed, not scientific, nor justifiable to worry, but just to continue with the checks. Recall that more than 8 million doses of AstraZeneca have been used in the UK and there has been no serious adverse reaction, underlined Gianni Rezza, Director of Prevention at the Ministry of Health. AstraZeneca for its part has issued a note in which it specifies: From an analysis of our safety data on over 10 million administrations there was no evidence of an increased risk of pulmonary embolism or deep vein thrombosis in any group of age, gender, batch or any country where the vaccine was used. The number of these events was significantly lower in vaccinated subjects than the number observed in the general population.

The actions of the states

Currently several states have adopted precautionary measures: Austria, Estonia, Lithuania, Luxembourg and Latvia have suspended the inoculations of the “suspect” batch, Abv5300. Denmark, Bulgaria, Norway and Iceland have suspended all serum administrations of AstraZeneca. Italy has blocked only one batch, the number Abv285, and continues the vaccination campaign with the remaining doses. The World Health Organization (WHO) said it is evaluating reports of blood clotting problems detected in some EU citizens who have received doses of the AstraZeneca vaccine against Covid-19, specifying that there is no reason to quit to use the AstraZeneca vaccine against Covid.

March 12, 2021 (change March 12, 2021 | 12:43)

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