Adjuvanted inactivated rabies virus-vectored Lassa virus vaccine in healthy adults: a phase 1 trial - Report - MDSpire

Adjuvanted inactivated rabies virus-vectored Lassa virus vaccine in healthy adults: a phase 1 trial

  • By

  • Justin R. Ortiz

  • Drishya Kurup

  • Adam C. Kaufman

  • Sabrine Ben Hamed

  • Allison M. LaRocco

  • Kirsten E. Lyke

  • Sarah M. Litts

  • Shrimati Datta

  • Yuanyuan Liang

  • Megan F. McGilvray

  • Jeannie A. Losignor

  • Jennifer J. Oshinsky

  • Kari V. Palmer

  • Ifayet PL Johnson-Mayo

  • Gabrielle Scher

  • Uthra Balakumar

  • Anisha Chandwani

  • Rekha R. Rapaka

  • Meagan E. Deming

  • Joel V. Chua

  • Christoph Wirblich

  • Wilbur H. Chen

  • Kathleen M. Neuzil

  • Marcela F. Pasetti

  • Matthias J. Schnell

  • June 9, 2026

  • 0 min

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Clinical Report: Phase 1 Trial of an Adjuvanted Inactivated Rabies Virus-Vectored Vaccine for Lassa Virus in Healthy Adults

Overview

This report presents interim findings from a Phase 1 trial evaluating the safety and immunogenicity of the LASSARAB vaccine, an adjuvanted inactivated rabies virus-vectored vaccine for Lassa virus. The trial included healthy adults and assessed various dosing regimens.

Background

Lassa fever is a significant public health concern in West Africa, with high morbidity and mortality rates. The absence of licensed vaccines highlights the urgent need for effective preventive measures against this viral hemorrhagic fever. Understanding immune responses to Lassa virus is crucial for developing effective vaccines.

Data Highlights

No numerical data or trial results were provided in the source material.

Key Findings

  • The trial enrolled healthy, nonpregnant adults aged 18-50 years.
  • Participants were divided into four groups receiving different doses of the LASSARAB vaccine.
  • Group A received 700 rU of antigen with 5 µg of adjuvant, while Group B received 1,400 rU with the same adjuvant dose.
  • Group C received two concurrent injections totaling 2,800 rU of antigen and 10 µg of adjuvant.
  • Group D served as the control, receiving the licensed inactivated rabies vaccine.
  • All participants completed follow-up through day 61.

Clinical Implications

The findings from this trial may inform future vaccine development strategies for Lassa fever. Understanding the safety and immunogenicity of the LASSARAB vaccine is essential for advancing to later-phase trials.

Conclusion

The interim analysis of the Phase 1 trial indicates the potential of the LASSARAB vaccine as a candidate for Lassa fever prevention. Further studies are needed to confirm these findings.

Related Resources & Content

  1. Nature Medicine, 2026 -- Favipiravir for Lassa fever: an open-label, randomized controlled phase 2 trial
  2. Open Forum Infectious Diseases, 2023 -- Phase 1 Randomized Clinical Trial Evaluating a Combined Protein-Based Virus-Like Particle Vaccine for Respiratory Syncytial Virus and Human Metapneumovirus in Adults Aged 60 to 75
  3. The Journal of Infectious Diseases, 2023 -- Evaluation of Safety and Immune Response of a Prefusion-Stabilized SARS-CoV-2 Spike Subunit Vaccine Using a Second-Generation Molecular Clamp in Adults Aged 18 to 55: Results from a Phase I Randomized, Double-Blind, Active Comparator Trial
  4. Lassa fever -- WHO Fact Sheet
  5. Infection Prevention and Control Recommendations for Patients in U.S. Hospitals who are Suspected or Confirmed to have Selected Viral Hemorrhagic Fevers (VHF) | CDC
  6. The Journal of Infectious Diseases — Evaluation of Safety and Immune Response of the Klebsiella pneumoniae Tetravalent Bioconjugate Vaccine (Kleb4V) in Healthy Adults: Results from a Phase I/II Randomized Controlled Trial
  7. Lassa Fever Training for Healthcare Providers | CDC
  8. Lassa fever
  9. Infection Prevention and Control Recommendations for Patients in U.S. Hospitals who are Suspected or Confirmed to have Selected Viral Hemorrhagic Fevers (VHF) | Viral Hemorrhagic Fevers (VHFs) | CDC
  10. Viral Hemorrhagic Fever (VHF) 2025 Case Definition | CDC
  11. Immunogenicity of an adjuvanted, combination inactivated rabies-vectored, Lassa fever vaccine in healthy adults: interim results of a first-in-human Phase 1 trial | medRxiv
  12. Safety and Immunogenicity of an rVSV Lassa Fever Vaccine Candidate | New England Journal of Medicine
  13. Fast facts about IAVI’s contributions to fighting Lassa fever in West Africa - IAVI
  14. Frontiers | Safety, tolerability, and immunogenicity of INO-4500, a synthetic DNA-based vaccine against Lassa virus, in a phase 1b clinical trial in healthy Ghanaian adults
  15. Favipiravir for Lassa fever: an open-label, randomized controlled phase 2 trial | Nature Medicine
  16. Lack of Evidence for Ribavirin Treatment of Lassa Fever in Systematic Review of Published and Unpublished Studies - PMC

Original Source(s)

Adjuvanted inactivated rabies virus-vectored Lassa virus vaccine in healthy adults: a phase 1 trial

  • by Justin R. Ortiz, Drishya Kurup, Adam C. Kaufman, Sabrine Ben Hamed, Allison M. LaRocco, Kirsten E. Lyke, Sarah M. Litts, Shrimati Datta, Yuanyuan Liang, Megan F. McGilvray, Jeannie A. Losignor, Jennifer J. Oshinsky, Kari V. Palmer, Ifayet PL Johnson-Mayo, Gabrielle Scher, Uthra Balakumar, Anisha Chandwani, Rekha R. Rapaka, Meagan E. Deming, Joel V. Chua, Christoph Wirblich, Wilbur H. Chen, Kathleen M. Neuzil, Marcela F. Pasetti, Matthias J. Schnell

  • June 9, 2026

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