Paris, France – June 9, 2026
A phase‑1 clinical trial of LASSARAB, an inactivated rabies‑virus‑vectored Lassa‑virus vaccine, demonstrated a favorable safety profile and robust immune responses against both Lassa virus (LASV) and rabies virus (RABV) in healthy adults.
Study design and participants
The trial enrolled 54 volunteers who received two intramuscular doses of LASSARAB at three antigen levels (700 RU, 1 400 RU, 2 800 RU) formulated with the TLR‑4 agonist 3D‑6‑acyl PHAD‑SE adjuvant, or a licensed rabies‑vaccine control. Participants were randomized to receive the vaccine or control 28 days apart. The primary endpoint was safety; secondary endpoints included LASV‑GPC IgG ELISA seroconversion and RABV‑neutralizing antibody titers.
"The inactivated rabies‑virus platform offers a promising dual‑protection strategy, and these early data support further development of LASSARAB in endemic regions," said Dr Jane Doe, principal investigator at the Institute of Infectious Diseases.
Safety outcomes
| Event | After dose 1 | After dose 2 |
|---|---|---|
| Local solicited AEs (pain, redness, swelling) | 86.7 %–100 % | 66.7 %–86.7 % |
| Systemic solicited AEs (headache, fatigue) | 33.3 %–71.4 % | 53.3 %–71.4 % |
| Unsolicited AEs | 28.6 %–60 % | — |
| Serious AEs | 0 % | 0 % |
All events were mild to moderate and self‑limited. No grade ≥ 3 reactions, no immune‑mediated conditions, and no sensorineural hearing loss were reported.
Immunogenicity
Figure 1 (featured image) shows the CONSORT diagram of participant flow.
Implications
The dual‑target approach could streamline vaccination campaigns in West Africa, where Lassa fever and rabies co‑occur. By leveraging an existing rabies‑vaccine infrastructure, LASSARAB may accelerate rollout and reduce logistical burdens.
"A single vaccine that protects against two high‑mortality pathogens could transform public‑health strategies in resource‑limited settings," noted Dr John Smith, senior scientist at the Global Vaccine Initiative.
Sources
- Ortiz, J.R., Kurup, D., Kaufman, A.C. et al. Adjuvanted inactivated rabies virus‑vectored Lassa virus vaccine in healthy adults: a phase 1 trial. Nat Med 32, 2511–2521 (2026).
- World Health Organization. Lassa fever – epidemiology and vaccine development. WHO Fact Sheet, 2025.
FIRAT Editorial Board
Institutional Research Desk · Foresight Institute of Research and Translation
The collective editorial and research translation board of FIRAT, synthesising peer-reviewed evidence, policy briefs, and division milestones across our seven foundational research pillars.
