A case-control study indicates that, while the relative risk of contracting carditis after the injection of the Pfizer vaccine is accentuated, the absolute risk, meanwhile, remains very low.
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[EN VIDÉO] Covid-19: Pfizer announces that its vaccine is 90% effective Pfizer and BioNTech have just announced the latest results regarding the effectiveness of their coronavirus vaccine. It is 90% effective in preventing Covid-19. They hope to produce millions of doses by the end of the year.
A case-control study conducted in Hong Kong indicates that, although the absolute risk is very low, the relative risk of carditis is accented after vaccine of Pfizer. inflammation of the heart which can affect the myocardium, the muscle, or the pericardium, the tissue surrounding the heart. In rare cases, carditis can occur after a bacterial, viral or parasitic infection. Cases of myocarditis have also been reported after the injection of anti-Covid-19 vaccines based onmRNA, mainly in young men.
Three times higher risk of carditis in young men after injection of Pfizer vaccine
To find out if the Pfizer vaccine and that of coronavac, a live inactivated and adjuvanted vaccine, constitute a risk factor for carditis, the researchers followed 160 sick patients and 1,533 healthy patients. After analysis, 20 cases of carditis were associated with the Pfizer vaccine and 7 with that of Coronavac. Thus the relative risk of declaring carditis is 3.57 higher after a Pfizer vaccine, in comparison with non-vaccinated persons with the same profile. This increase was not observed for the Coronavac vaccine. If we analyze the figures a little more, it appears that this relative risk is higher for men : 4.68 times more risk of carditis in them, against 2.22 times for women. The relative risk is also greater after the second dose of Pfizer than the first.
Even so, the absolute risk of developing inflammation of the heart after the Pfizer vaccine is very weak. The cumulative incidence of carditis in vaccinees is only 0.52 cases per 100,000 doses injected. None of the 20 cases of carditis diagnosed was fatal, nor required intensive care.
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