Hospital.Help

Paris – Most young people who develop myocarditis after being vaccinated against COVID-19 recover completely. In a cohort study from France, only a few patients had to be hospitalized again for cardiovascular problems in the following year and a half.

The incidence was based on a publication in the American Medical Journal (JAMA 2024; DOI: 10.1001/jama.2024.16380), the risk of myocarditis was only half as high as in patients who had developed myocarditis as a result of COVID-19 or for other reasons.

In rare cases (about 1:10,000) myocarditis can occur after vaccination with an mRNA vaccine (BNT162b2 or mRNA-1273). Younger men are often affected and often become ill after the second dose.

In France, by the end of June 2022, 558 people aged between 12 and 49 had to be hospitalized for myocarditis in the first week after a dose of vaccine. Another 298 patients were hospitalized for myocarditis that occurred within 30 days of contracting COVID-19. The remaining 3,779 patients had no connection with COVID-19 or vaccination.

Most patients (376 of 558) became ill after the second vaccination dose. Most cases of myocarditis were apparently relatively mild and the patients were able to leave the hospital after a median of four days. Only one patient had to be temporarily treated with extracorporeal membrane oxygenation (ECMO). He was later able to leave the hospital alive. No patient required a heart transplant.

A team led by Mahmoud Zureik from the French drug agency ANSM (“Agence nationale de sécurité du médicament et des produits de santé”) investigated how often the patients were re-hospitalized in the following 18 months.

Of the 558 patients with myocarditis after mRNA vaccination, 32 patients (5.7%) had to be re-hospitalized for cardiovascular problems. Of these, 25 (6.1%) had been vaccinated with BNT162b2 from BioNTech/Pfizer and 7 (4.7%) with mRNA-1273 from Moderna.

Of the 298 patients with myocarditis after COVID-19, 36 patients (12.1%) were rehospitalized for cardiovascular problems, compared to 497 of 3,779 patients (13.2%) after conventional myocarditis.

The ANSM team determined a weighted hazard ratio of 0.55 for patients after the vaccination complication compared to conventional myocarditis. This was significant with a 95% confidence interval of 0.36 to 0.86.

Following vaccine-related myocarditis, rehospitalization for cardiovascular complications was 45% less common. In contrast, myocarditis after COVID-19 had cardiovascular aftereffects just as often as conventional myocarditis, with a weighted hazard ratio of 1.04 (0.70-1.52).

Comparing the two vaccines, the researchers determined a weighted hazard ratio of 0.68 (0.38-1.22) for BNT162b2 and a weighted hazard ratio of 0.24 (0.05-1.18) for mRNA-1273. The Moderna vaccine would therefore be less likely to be affected by the after-effects. However, the number of cases was too small to make a statistically reliable statement.

One patient (0.2%) died in the first 18 months after vaccine-associated myocarditis. There were four deaths (1.3%) after COVID-19-associated myocarditis and 49 deaths (1.3%) after conventional myocarditis.

Zureik concludes that overall, cardiovascular complications are less common in patients with vaccine-related myocarditis than in patients with conventional myocarditis. © rme/aerzteblatt.de