Skip to main content
Journal cover image

Metformin on the Presence of COVID-19 Symptoms 6 Months after Infection: The ACTIV-6 Randomized Clinical Trial.

Journal articles  - Journal Article
Bramante, CT; Stewart, TG; Boulware, DR; McCarthy, MW; Gao, Y; Rothman, RL; Mourad, A; Thicklin, F; Cohen, JB; Garcia Del Sol, IT; Shah, NS ...
Published in: Clin Infect Dis
June 4, 2026

BACKGROUND: We conducted a quadruple-blinded, randomized, placebo-controlled trial of metformin for treating acute SARS-CoV-2 infection to prevent long COVID symptoms in low-risk adults. METHODS: The ACTIV-6 platform evaluated repurposed medications for mild to moderate COVID-19. Between September 19, 2023 and May 1, 2024, 2983 outpatient adults ≥30 years with confirmed SARS-CoV-2 infection and ≥2 COVID-19 symptoms were included within 7 days of symptom onset from 90 sites. Participants were randomized to metformin or placebo for 14 days. Post-acute sequelae of SARS-CoV-2 or death (PASCD) was ascertained by asking whether participants had symptoms they attributed to COVID-19 on day 180. Secondary outcomes included clinician-diagnosed long COVID. RESULTS: The median age was 47 years (interquartile range 38-57); 63% were female; 47% Hispanic/Latino; 83% reported ≥1 prior COVID-19 infections or ≥2 SARS-CoV-2 vaccines. There were no deaths. Overall, 96 (3.2%) reported COVID-19 symptoms on day 90, 101 (3.4%) on day 120, and 79 (2.6%) on day 180. The adjusted risk of symptoms on day 180 was 0.8 percentage points lower with metformin (95% credible interval [CrI] -2.2 to 0.6) with a posterior probability of efficacy [PPE] for preventing symptoms of 0.83, risk ratio 0.79 (95% CrI 0.474 to 1.230). Compared with placebo, the risk of clinician-diagnosed long COVID was 0.7 percentage points lower with metformin (95% CrI -1.5 to 0.1); PPE 0.96; risk ratio 0.495 (95% CrI 0.155 to 0.995). CONCLUSIONS AND RELEVANCE: In low-risk adults, most with prior immunity, metformin did not exceed the efficacy threshold of 0.975 for PASC. Metformin reduced the risk of clinician-diagnosed long COVID.

Duke Scholars

Altmetric Attention Stats
Dimensions Citation Stats

Published In

Clin Infect Dis

DOI

EISSN

1537-6591

Publication Date

June 4, 2026

Location

United States

Related Subject Headings

  • Microbiology
  • 3202 Clinical sciences
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Bramante, C. T., Stewart, T. G., Boulware, D. R., McCarthy, M. W., Gao, Y., Rothman, R. L., … Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV)-6 Study Group and Investigators. (2026). Metformin on the Presence of COVID-19 Symptoms 6 Months after Infection: The ACTIV-6 Randomized Clinical Trial. Clin Infect Dis. https://doi.org/10.1093/cid/ciag335
Bramante, Carolyn T., Thomas G. Stewart, David R. Boulware, Matthew W. McCarthy, Yue Gao, Russell L. Rothman, Ahmad Mourad, et al. “Metformin on the Presence of COVID-19 Symptoms 6 Months after Infection: The ACTIV-6 Randomized Clinical Trial.Clin Infect Dis, June 4, 2026. https://doi.org/10.1093/cid/ciag335.
Bramante CT, Stewart TG, Boulware DR, McCarthy MW, Gao Y, Rothman RL, et al. Metformin on the Presence of COVID-19 Symptoms 6 Months after Infection: The ACTIV-6 Randomized Clinical Trial. Clin Infect Dis. 2026 Jun 4;
Bramante, Carolyn T., et al. “Metformin on the Presence of COVID-19 Symptoms 6 Months after Infection: The ACTIV-6 Randomized Clinical Trial.Clin Infect Dis, June 2026. Pubmed, doi:10.1093/cid/ciag335.
Bramante CT, Stewart TG, Boulware DR, McCarthy MW, Gao Y, Rothman RL, Mourad A, Thicklin F, Cohen JB, Garcia Del Sol IT, Shah NS, Mehta M, Quintero Cardona O, Scott J, Ginde AA, Castro M, Jayaweera D, Sulkowski M, Gentile N, McTigue K, Felker GM, Collins S, Dunsmore SE, Adam SJ, Lindsell CJ, Hernandez AF, Naggie S, Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV)-6 Study Group and Investigators. Metformin on the Presence of COVID-19 Symptoms 6 Months after Infection: The ACTIV-6 Randomized Clinical Trial. Clin Infect Dis. 2026 Jun 4;
Journal cover image

Published In

Clin Infect Dis

DOI

EISSN

1537-6591

Publication Date

June 4, 2026

Location

United States

Related Subject Headings

  • Microbiology
  • 3202 Clinical sciences