LONDON — A new experimental rabies vaccine has entered human testing in the United Kingdom, using self-amplifying RNA that could allow very small doses to produce a stronger immune response.
Called RAB-Vac, the vaccine is being developed by scientists at Imperial College London and is being tested at Chelsea and Westminster Hospital. The programme is supported by the Coalition for Epidemic Preparedness Innovations, or CEPI.
The Phase I study involves 48 healthy adults aged 18 to 50. Researchers will assess safety and monitor the immune response, including antibody levels and T-cell and B-cell activity.The study is not designed to establish whether RAB-Vac can prevent rabies infection.
The technology behind the vaccine is the unusual part. RAB-Vac uses self-amplifying RNA, known as saRNA, packed inside lipid nanoparticles. Once the RNA enters cells, it carries instructions that allow it to make additional copies of itself for a limited period. The aim is to produce enough vaccine protein to activate the immune system while using a much smaller amount of RNA.
Three dose levels are being examined: 0.2 micrograms, 1 microgram and 5 micrograms. Participants will receive three injections under different schedules, with immune responses measured over time.
WHO estimates that tens of thousands of people die from rabies every year, with most deaths occurring in Africa and Asia.
India carries a major share of the global burden. WHO estimates that the country accounts for about 35 per cent of rabies deaths worldwide. Effective rabies vaccines already exist. Access, production and delivery remain difficult in many parts of the world, particularly in countries carrying the heaviest disease burden.
RAB-Vac is being developed around the possibility of using much smaller RNA doses and making vaccine production more efficient at scale.
Participants will be followed for about a year, while the wider study is expected to run for roughly 21 months.
The vaccine remains experimental and has not been approved as a replacement for existing rabies vaccines.
