A groundbreaking clinical trial for a potential Lassa fever vaccine has commenced at the University of Maryland School of Medicine, marking a significant step towards combating this deadly viral hemorrhagic disease. Originating from rodents common in West Africa, Lassa fever poses severe health risks, including fatalities and permanent hearing loss. This Phase 1 trial, sponsored by NIH’s National Institute of Allergy and Infectious Diseases (NIAID), aims to assess the safety and immune response of the experimental vaccine among healthy adults. The vaccine leverages an attenuated rabies vaccine platform, modified to target both rabies and Lassa virus proteins.

The trial focuses on evaluating three dosage levels of the vaccine candidate, administered through two injections spaced 28 days apart. Participants will either receive the vaccine or a licensed rabies vaccine as a control group. Preceding studies with nonhuman primates demonstrated promising results, showing complete protection against lethal doses of Lassa virus after vaccination. If successful, this dual-purpose vaccine could revolutionize prevention strategies for both Lassa fever and rabies.

Pioneering Research Behind the Vaccine Candidate

This innovative vaccine originates from research conducted by a team at Thomas Jefferson University, supported by NIH funding. Their work centers on creating a vaccine capable of eliciting immune responses against both rabies and Lassa fever. The foundation of the vaccine lies in a weakened rabies vaccine that is then inactivated and modified to express specific proteins from both diseases.

In detail, the vaccine's development process involves utilizing a deactivated rabies vaccine base, which is further altered to include the glycoprotein precursor complex (GPC) of the Lassa virus. This approach ensures the body recognizes and responds to antigens from both pathogens. Preclinical trials on nonhuman primates have shown that two doses of the vaccine, given four weeks apart, provide robust protection against high doses of Lassa virus exposure. These findings underline the vaccine's potential efficacy and pave the way for its evaluation in human subjects.

Phase 1 Clinical Trial Design and Objectives

Up to 55 healthy adult volunteers between the ages of 18 and 50 will participate in this initial phase of testing. Researchers aim to determine the optimal concentration of the vaccine while ensuring its safety and immunogenicity. Participants will be randomly assigned to receive either the experimental vaccine or a standard rabies vaccine used as a comparator.

Each participant will undergo two injection sessions separated by a month-long interval. The study monitors their reactions closely to gauge any adverse effects and measure antibody production levels against both rabies and Lassa fever components. By comparing outcomes across different dosage groups, scientists hope to identify the most effective formulation for advancing into subsequent phases of clinical investigation. Success in this stage would bring humanity closer to possessing a reliable defense mechanism against these dangerous diseases.