The WHO Solidarity Trial: Key Findings on Repurposed Drugs for COVID-19

The WHO Solidarity trial, one of the largest international randomized controlled trials for COVID-19 treatments, has delivered its final results on the effectiveness of several repurposed antiviral drugs. Conducted across 52 countries and involving over 14,000 hospitalized patients, the trial aimed to determine whether existing medications could reduce mortality in people with severe or critical COVID-19.

The study evaluated four repurposed drugs: remdesivir, hydroxychloroquine, lopinavir/ritonavir, and interferon beta-1a. Patients were randomly assigned to receive one of these drugs (where locally available) or the local standard of care alone, with no placebos used. The primary outcome measured was in-hospital mortality.

Interim Findings Led to Early Discontinuation of Three Drugs

Based on interim analyses, the trial’s independent data monitoring committee found that hydroxychloroquine, lopinavir/ritonavir, and interferon beta-1a showed little or no effect on reducing mortality, ventilation initiation, or hospital discharge duration. Recruitment for these three arms was discontinued for futility.

Randomization to remdesivir continued, as interim data suggested a potential signal of benefit that warranted further investigation.

Final Results Show Limited Impact on Mortality

The final analysis, published in The Lancet in May 2022, concluded that remdesivir, hydroxychloroquine, lopinavir/ritonavir, and interferon beta-1a had little or no effect on overall in-hospital mortality compared to the control group. These findings were consistent across subgroups, including patients requiring oxygen support at baseline.

The results were further supported by updated meta-analyses combining Solidarity data with other relevant trials, reinforcing the conclusion that none of these four repurposed antivirals significantly improved survival in hospitalized COVID-19 patients.

Implications for Clinical Practice and Future Research

While the Solidarity trial did not find mortality benefits for these specific repurposed drugs, it demonstrated the value of large, adaptive platform trials in rapidly evaluating multiple therapies during a public health emergency. The trial’s design allowed for swift discontinuation of ineffective arms and continuation of promising ones, accelerating the generation of reliable evidence.

The findings have informed global treatment guidelines, steering clinical focus toward other interventions such as corticosteroids (like dexamethasone), immunomodulators, and antiviral agents specifically developed for SARS-CoV-2. Ongoing research continues to explore novel therapeutics and combination strategies for COVID-19 and future pandemic preparedness.

Key Takeaways

• The WHO Solidarity trial tested four repurposed drugs for COVID-19: remdesivir, hydroxychloroquine, lopinavir/ritonavir, and interferon beta-1a.
• Interim analyses showed no mortality benefit for hydroxychloroquine, lopinavir/ritonavir, or interferon beta-1a, leading to their discontinuation.
• Final results confirmed that none of the four drugs significantly reduced in-hospital mortality.
• The trial’s adaptive design enabled rapid, evidence-based decisions during the pandemic.
• These results have guided global clinical recommendations toward more effective treatments for severe COVID-19.