The long-term neurologic symptoms such as "brain fog" experienced by some patients with COVID-19 may be caused by a unique pathology — the occlusion of brain capillaries by large megakaryocyte cells, a new report suggests. The authors report five separate post-mortem cases from patients who died with COVID-19 in which large cells resembling megakaryocytes were identified in cortical capillaries. Immunohistochemistry subsequently confirmed...