A study led by the Duke Clinical Research Institute (DCRI) in partnership with Vanderbilt University found no symptomatic or clinical benefit to taking the antidepressant fluvoxamine 50 mg twice daily for 10 days for the treatment of mild-to-moderate COVID-19 symptoms.

“There was no evidence of improvement in time to recovery in participants who took this dose of fluvoxamine versus those who took a placebo,” said Adrian Hernandez, M.D., the study’s administrative principal investigator and executive director of the DCRI.

Findings appear on medRxiv, a pre-publication server, and have been submitted to a peer-reviewed journal.

Researchers looked at the rate of sustained recovery, defined as three days without symptoms, in ACTIV-6. While 75% of participants were still reporting symptoms at day 7, the majority (82%) of these participants reported no limitation in activities.

“This finding may reflect the decreased severity of COVID-19 symptoms in a vaccinated population,” Hernandez said. “In future COVID-19 research, we may want to consider evaluating functional status instead of symptom relief.”

Close to 70% of the 1,227 participants who enrolled in this study reported having received two or more doses of a COVID-19 vaccine. Study enrollment opened in August 2021 and participants either took 50-mg tablets of fluvoxamine or a matching placebo twice daily for 10 days. Participants tolerated this dose well with very few side effects such as diarrhea reported by people receiving fluvoxamine or placebo.

ACTIV-6 -- “The Randomized Trial to Evaluate Efficacy of Repurposed Medications” -- is a nationwide double-blind study that has enrolled more than 5,000 participants. The trial continues to enroll participants from across the United States to evaluate the potential benefits for treating mild-to-moderate COVID-19 with repurposed medications.

Repurposed medications are those already approved by the U.S. Food and Drug Administration (FDA) for other medical indications. Fluvoxamine is one of three FDA-approved repurposed medications currently being tested in ACTIV-6.

Fluvoxamine is a selective serotonin reuptake inhibitor, which is used to treat obsessive-compulsive disorder and depression. It is not approved by the FDA to treat COVID-19 and should only be taken as prescribed or as part of a clinical trial. Fluvoxamine was chosen for this study because previous evidence suggested that it may be able to reduce inflammation due to the virus. In addition to fluvoxamine 50 mg twice daily for 10 days, the ACTIV-6 team is also testing fluvoxamine 100 mg twice daily for 13 days.

“Other research suggests that 100 mg of fluvoxamine taken twice daily may be effective in treating COVID-19, but tolerance may be a limitation,” said Susanna Naggie, M.D., the DCRI principal investigator overseeing the study’s clinical coordinating center. “We set out to test if 50 mg taken twice daily is effective and tolerated. We learned efficacy is not achieved at the lower dose of fluvoxamine and look forward to learning of and sharing results from the open study arm testing the higher dose.”

In addition to Drs. Hernandez and Naggie, members of the ACTIV-6 Executive Committee include Stacey Adam, David Boulware, Sean Collins, Allison DeLong, Sarah Dunsmore, G. Michael Felker, George Hanna, Chris Lindsell, Matthew McCarthy, April Remaly, Elizabeth Shenkman, Thomas Stewart, Florence Thicklin, Rhonda Wilder, and Sybil Wilson.

ACTIV-6 (ClinicalTrials.gov identifier NCT04885530) received funding from the National Institutes of Health (3U24TR001608-06S1).