THEMyocarditis and pericarditis are inflammations of the myocardium (the muscle tissue of the heart) and the pericardium (the membrane that surrounds the heart muscle), respectively. The inflammation itself is not directly caused by the vaccine or the virus, explains Dr. Bernard Cantin of the Institute of Heart and Pneumology of Quebec: “Most likely, the vaccine or virus will react. The immune system is the immune system. the reaction, which is sometimes exaggerated, can spread throughout the body and is slightly out of control. This is what will ultimately damage the cells of the heart. [même en l’absence de virus ou de vaccin dans les cellules cardiaques] some people. “
It may seem counterintuitive that the immune system can damage our own cells when it is supposed to protect them, but it can be viewed as an army defending a city from an invader. To repel the latter, the army must also use firearms, tanks, explosives, etc., so it will inevitably cause damage to the city in its defense. Immune responses can include a little (and sometimes a lot) of this.
It is true that myo- and pericarditis can be caused by both vaccines and the viruses themselves. “All of these immune responses travel through the same cytokines (editor’s note: a protein that signals an alarm and attracts immune cells to the site of infection) through the same channels,” says Dr. Cantin. So yes, he continues, it is possible that some people have a predisposition to complications such as myo- and pericarditis, and that this predisposition applies to both vaccines and natural infections. It could have been.
Moreover, in an article published in a medical journal Circulation Last week, the authors noted that, in general, people with myocarditis have more “autoantibodies” (which are antibodies that attack cells in the body, rather than just target viruses), and that their first-degree relatives (parents, siblings) also produce, on average, more of these “autoantibodies”. Thus, this suggests that with certain complications, people may have vulnerabilities that, in principle, apply to both vaccines and natural infections.
However, this does not mean that a strong reaction to one necessarily means that the other will cause severe symptoms, warns Dr. Cantin. First, because immune responses are very individual and each person will respond to infections / vaccines differently. And secondly, since the severity of symptoms is not always related to the severity of the disease, the virus may not cause many symptoms, for example, in immunocompromised patients, but still be serious, because these people cannot get rid of it.
On the other hand, in addition to some specific vulnerabilities, there is also reason to believe that, in general, the severity of the side effects of the vaccine does not matter much to the symptoms a vaccinated person would have if they had COVID. Thus, we know that SARS-CoV-2 causes, on average, more severe symptoms in older people than in the youngest: people 70 years and older accounted for almost half (47.7%) of hospitalizations due to COVID-19 this year in Quebec, when they only make up 13.5% of the population. Likewise, men appear to be more vulnerable to COVID, with a (standardized) hospitalization rate of 64 per 100,000 compared to 34 per 100,000 women. And it is natural that people with risk factors (hypertension, obesity, etc.) are more prone to a severe form of the disease.
However, if the side effects of the vaccine were correlated with the side effects of COVID, one would expect older adults, men, and people with underlying medical conditions to respond more strongly to vaccines than average. But we see just the opposite. In a study published last April in Lancet on Pfizer / BioNtech and AstraZeneca / Oxford vaccines, the Anglo-American team found that people under 55, for example, reported more “systemic side effects” (fatigue, headache, fever, chills, etc.) than people over 55 years old. about 18% versus 32% after the second dose of Pfizer. The same is true for men: about 25–27% of women reported systemic effects, compared with about 17% for men. And the same rule applied for comorbidities (with the exception of obesity, which was associated with more adverse effects in overweight people).
So no, overall, the greater or lesser severity of the side effects of the COVID vaccines does not really matter in terms of the type of COVID we would have.