A more detailed analysis of the inflammatory cell composition showed a marked increase of macrophages (CD68 +) in all infectious groups compared to controls, with influenza cases displaying the most prominent infiltrate (130.2 ± 1.0) with a twofold higher number of macrophages per mm2 compared to COVID-19 (65.2 ± 0.8) and common myocarditis (72.5 ± 1.6) (Fig. 2, supplementary table 3). Here, CD68 is linked to COVID-19.