BackgroundThe ongoing COVID-19 pandemic demands a series of measures and, above all, the vaccination of a substantial proportion of the population. Acute myocarditis is a rare complication of the widely used mRNA-based vaccines.Case PresentationWe present a case series of four patients (three men and one woman, 16 to 47 years old) with acute pericarditis/myocarditis 3 to 17 days after mRNA vaccination. They presented with chest pain, fever, and flu-like symptoms. Diagnosis was made based on the synopsis of clinical presentation, elevated levels of troponin T and NT-proBNP, impaired systolic function on echocardiography, and findings in non-invasive tissue characterization by cardiovascular magnetic resonance imaging. Two patients also underwent endomyocardial biopsies. As none of the patients showed signs of cardiogenic shock, they were discharged from ward care only a few days after their initial presentations.ConclusionsOur data are consistent with other case reports of myocarditis early after mRNA vaccination and demonstrate the need for multimodal diagnostics. In view of its rarity and mild course, the risk–benefit ratio of vaccination remains positive compared to potential SARS-CoV-2 infection.

Both automated CLIA demonstrated excellent diagnostic sensitivity and specificity when evaluated as a screening test for syphilis under routine conditions of a diagnostic laboratory. Thus, these may be used independently as an alternative to the manual TPPA screen.

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Background The anti‐coronavirus disease 2019 (COVID‐19) vaccines are of paramount importance in the fight against the COVID‐19 pandemic. Both viral vector‐ and nucleic acid‐based vaccines are known to effectively induce protection against the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) virus by generating high antibody titers and effective T‐cell responses to the spike protein they encode. Although these vaccines are being applied worldwide and have been extensively investigated, the immunomorphological events at the vaccination site with respect to SARS‐CoV‐2 spike protein expression have not yet been described. Methods We had the opportunity to examine the deltoid muscles of three men who died shortly after vaccination for unrelated reasons. We examined the vaccination sites histologically and immunohistochemically with various antibodies. Furthermore we incubated two different cell lines with one vaccine and examined the expression of the spike protein. Results The vaccination sites show a dense lymphohistiocytic interstitial infiltrate which surrounds the small vessels and extends into the perimysium. The spike protein is expressed by histiocytic cells with a dendritic shape that are CD68‐positive and CD207‐negative, fibrocytes, and very rare S100‐positive cells. Interestingly, the skeletal muscle, being constitutively human leukocyte antigen (HLA)‐A,B,C‐negative, is induced at different levels in each specimen. In a cell culture experiment, we confirmed the ability of fibroblasts and interdigitating dendritic sarcoma cells to express spike protein in vitro after incubation with the Comirnaty vaccine. Conclusions Histiocytic cells and fibrocytes are the heralds of spike protein synthesis at the vaccination site. The underlying cause of this apparent cell specifity is unknown. This needs to be investigated in future experiments, for example in an animal model.