COVID-19: Famotidine, Histamine, Mast Cells, and Mechanisms

SARS-CoV-2 infection is required for COVID-19, but many signs and symptoms of COVID-19 differ from common acute viral diseases Currently, there are no pre- or post-exposure prophylactic COVID-19 medical countermeasures Clinical data suggest that famotidine may mitigate COVID-19 disease, but both mechanism of action and rationale for dose selection remain obscure We explore several plausible avenues of activity including antiviral and host-mediated actions We propose that the principal famotidine mechanism of action for COVID-19 involves on-target histamine receptor H (2) activity, and that development of clinical COVID-19 involves dysfunctional mast cell activation and histamine release