A systematic review of the literature using the MEDLINE data base (1 January 1990–1 January 2023) was conducted to identify peer-reviewed publications relevant to the diagnosis, pathogenesis and treatment of neuro-COVID using the search terms angiotensin-converting enzyme 2 (ACE2), blood-brain barrier (BBB), brain, chemokines, corona virus, COVID-19, cytokines, endothelial cells, fatigue, fog, inflammation, Long-COVID, mast cell, microglia, neuroinflammation, toll-like receptors, and vasculature. The gene discussed is ACE2; the disease is COVID-19.