On April 10, 2024, a screenshot of an article that appeared on March 25, 2024 on The Chronicler, Argentine economic newspaper. The screenshot shows the Italian translation of a part of the original article, in Spanish. It reads: “COVID alert: 7 new diseases associated with Pfizer, Moderna and Astrazeneca vaccines discovered. Specialists from the Global Vaccine Data Network have identified new side effects linked to Covid-19 vaccines. Which ones are they?”.
This is misleading content, which conveys unfounded news.
The Global Vaccine Data Network (GVDN) is an international research network that aims to carry out studies on the effectiveness and safety of vaccines. The study to which the post under analysis refers was published in the scientific journal Vaccines.
The study examined a sample of 99 million subjects vaccinated with three anti-Covid-19 vaccines: the two mRNA vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) and the viral vector vaccine ChAdOx1 (Astrazeneca) . The objective of this study was to verify whether within this sample of vaccinated subjects there was a statistically significant increase in symptoms attributable to a series of neurological, hematological and cardiac diseases 42 days after administration of the vaccines.
The researchers calculated the ratio between observed and expected adverse events, that is, between the number of events recorded within the sample of vaccinated subjects and what would be expected in the absence of vaccination. The number of expected events is used as a background against which to estimate the possible increase in an event. The report therefore indicates whether there is a greater risk of developing a certain medical condition, at different time intervals, after receiving a vaccine compared to a period before administration. The large size of the sample studied allows us to find signs of even extremely rare side effects.
Regarding neurological diseases, among the signs of the most significant adverse events was an increase in cases of Guillan-Barrè syndrome after a first dose of the Astrazeneca vaccine, with 190 events out of 76 expected. It is a rare acute inflammatory polyneuropathy, of probable autoimmune origin, which in many cases is triggered by viral infections. This disease has also been found in people suffering from Covid-19. Another signal found is an increase in cases of acute disseminated encephalomyelitis after the administration of a dose of the Moderna vaccine, with seven events observed compared to two expected. This pathology can also be a consequence of infection with the Sars-CoV-2 virus.
Among hematological diseases, the most significant increase concerns cases of thrombosis of the cerebral venous sinus, following the first dose of the Astrazeneca vaccine, with 69 events observed out of 21. This is an obstruction of the venous vessels that drain blood from the brain. Cases of this rare pathology have been reported in patients suffering from Covid-19.
Among heart diseases, the most significant increase concerns cases of myocarditis and pericarditis after the administration of Pfizer and Moderna vaccines and of pericarditis after a third dose of the Astrazeneca vaccine. In the first case, it is an inflammation of the cardiac muscle tissue and, in the second, an inflammation of the membrane that lines the heart.
Commenting on the results, the study authors noted that «the safety signals identified in this study should be evaluated in the context of their rarity, severity and clinical relevance. Furthermore, overall assessments of the risk-benefit ratio of vaccination should take into account the risk associated with infection, as numerous studies have demonstrated a higher risk of developing the events under study, such as Guillain-Barré syndrome, myocarditis or l “acute disseminated encephalopathy, following SARS-CoV-2 infection compared to vaccination”. In fact, myocarditis and pericarditis have also been reported among the possible complications of Covid-19.
It should be remembered that already in 2021, following the suspension of batches of Astrazeneca vaccine in some European countries, including Italy, after the reporting of rare cases of deep vein thrombosis and disseminated intravascular coagulation, the European Medicines Agency (EMA) had carried out an evaluation which confirmed the favorable relationship between benefits and risks of the vaccine.
In conclusion, the study published in the journal Vaccines examined the data relating to the safety of the Pfizer, Moderna and Astrazeneca vaccines, calculating the frequency of possible side effects in a large sample of vaccinated people. But, contrary to what the post being analyzed states, it did not discover “7 new diseases associated with the Pfizer, Moderna and Astrazeneca vaccines”, because those described are conditions that had already been identified both among the rare adverse effects of the vaccines and among the same complications as Covid-19.
On Fact we have dealt with other misleading news regarding the safety of Covid-19 vaccines.
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