Researchers at the Bernhard Nocht Institute for Tropical Medicine (BNITM) and the University Medical Center Hamburg-Eppendorf (UKE) have conducted a randomized clinical trial on the treatment of Lassa fever for the first time. The drug candidate favipiravir proved to be safe and well tolerated. The results have been published in the journal Nature Medicine .

Lassa fever is a severe viral hemorrhagic fever disease that occurs mainly in West Africa. Every year, 100,000 to 300,000 people fall ill there. In hospitalized patients, the mortality rate is about 20 percent. So far, there is no approved vaccination and no therapy with clearly confirmed effectiveness. The previous standard ribavirin has been used for decades without randomized trials being able to prove its effectiveness.

In the SAFARI study, the scientists tested favipiravir – an antiviral agent originally developed against influenza – in patients with mild to moderate Lassa fever. The randomized controlled trial compared favipiravir with ribavirin. Favipiravir inhibits virus replication in a variety of RNA viruses, including the Lassa virus.

The results show that favipiravir may be a safe and tolerable alternative to ribavirin. In particular, the risk of anemia as a side effect seems to be lower. The study thus provides reliable data on a new therapy option for Lassa fever for the first time.

The researchers see favipiravir as a promising candidate for further studies, especially in severe cases and in combination with other drugs. Based on the pharmacokinetic data obtained, an adapted treatment regimen is now being tested in the international platform study INTEGRATE, in which the BNITM is a founding member.

The study was conducted in close collaboration with partners in Nigeria (Irrua Specialist Teaching Hospital and Federal Medical Center Owo). It was funded by the German Center for Infection Research (DZIF), the Federal Ministry of Health and the German Research Foundation, among others.

Original Paper:

Erameh C., Okwaraeke K et al. Favipiravir for Lassa fever: an open-label, randomized controlled phase II trial. Nature Medicine 2026, DOI: 10.1038/s41591-026-04402-w

Editor: X-Press Journalistenbüro GbR

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