Purpuric lesions on the pretibial area (A) and lower legs (D) of two vaccinees. Haematoxylin and eosin stain (original magnification × 2) shows swollen endothelial cells and a dense perivascular lymphocytic infiltrate with numerous extravasated erythrocytes, but no fibrinoid necrosis or thrombi (B, E). Examination of skin biopsy samples were done on days 2 and 5 after the onset of purpura, respectively. Immunostaining identifies the lymphocytic infiltrate as composed mainly of CD4+ T cells (C, F). Complement C3 was detected in the vessel walls and at the dermal epidermal junction (not shown), without IgG, IgM, or IgA deposits. rVSV-ZEBOV=recombinant vesicular stomatitis virus-based Zaire Ebola virus vaccine.