Fluvoxamine is a selective serotonin reuptake inhibitor (SSRI) which is being trialed for possible therapeutic use in COVID-19.
Fluvoxamine showed promise in a randomized, placebo-controlled trial of 152 COVID-19 positive outpatients. In a paper published in November, 2020 in the Journal of the American Medical Association:
Clinical deterioration occurred in 0 of 80 patients in the fluvoxamine group and in 6 of 72 patients in the placebo group (absolute difference, 8.7% [95% CI, 1.8%-16.4%] from survival analysis; log-rank P = .009). The fluvoxamine group had 1 serious adverse event and 11 other adverse events, whereas the placebo group had 6 serious adverse events and 12 other adverse events. -JAMA
Fluoxetine has also shown anti-SARS-CoV-2 activity in vitro in Vero and Calu-3 cells.
Mechanism of possible benefit?
Sigma-1 receptor
Mechanisms of potential benefit in COVID-19 may include sigma-1 receptor agonism. See "Fluvoxamine alleviates ER stress via induction of Sigma-1 receptor" and "Modulation of the sigma-1 receptor–IRE1 pathway is beneficial in preclinical models of inflammation and sepsis".
As SSRI
An observational study of 7,345 hospitalized COVID-19 patients hinted at possible benefit of prior SSRI usage.
As an anti-viral
In an October, 2020 preprint, fluoxetine showed in vitro anti-SARS-CoV-2 activity in Vero and Calu-3 cells.