This is an excerpt from an article originally published in The Leprosy Mission International’s Leprosy Insights Magazine #18. You can read the full article here.
Why has LepVax, the leprosy vaccine, taken decades to develop, while an effective Covid-19 vaccine took less than a year to create?
In May, The Leprosy Mission and Hope Rises International co-hosted a webinar to give an update on LepVax’s development, and how far we have left to go.
Dr Paul Saunderson, former Medical Director at Hope Rises International and retired clinician with ample experience in leprosy and neglected tropical diseases (NTDs), walked through the lengthy timeline leading up to this point. Multi-drug therapy (MDT) revolutionised leprosy treatment in 1981, and the discovery of the human and M. leprae genomes made the reality of a vaccine closer within reach. 25 years later, though, we still don’t have a vaccine.
Saunderson attributed LepVax’s slow development to a few causes: bacillus, the bacteria that grows leprosy, is a slow-developing bacteria, so trials take longer. Additionally, as is implied with the designation “neglected,” there is less political pressure, and thus less funding, for a vaccine.
You can watch the full webinar here.
How LepVax Works
LepVax works like “fight training”. The vaccine shows your body what the enemy looks like, so it knows how to fight when the enemy really appears.
1. The vaccine is applied: It contains harmless pieces of bacteria, and it does not cause the disease.
2. The body learns: The immune system recognises these pieces, creating a “memory” of defense.
3. The defense is activated: Defense cells (T lymphocytes) learn to attack the real bacteria.
4. Guaranteed protection: If the bacteria appear, the body already knows how to fight it, before and after contact.
What Makes LepVax Different?
LepVax is distinct from the BCG vaccine. The BCG vaccine was primarily developed for tuberculosis, but it also offers some level of protection against leprosy. Studies have shown BCG’s overall protective effect in preventing leprosy is just 26 percent, which is a far cry from full protection.
LepVax, in contrast to BCG, will offer full protection against leprosy, as it is designed specifically to prevent leprosy development. The vaccine is composed of LEP-F1 (a fusion of four leprosy antigens) that have proven acceptable and safe when administered in 21 healthy adults.
For preclinical evidence, researchers found the antigen reduced the M. leprae bacterial burden in the mouse model, and LepVax showed a safer nerve protection profile than BCG.
As for the goals of LepVax, the vaccine will reduce not only leprosy diagnoses, but it will also reduce nerve damage and cases of relapse, and it will enhance the wellbeing of those treated with the vaccine.
The Goals of LepVax
1. Prevent new cases: LepVax will stop transmission by vaccinating close contacts and people in endemic communities before they become infected.
2. Reduce impairment: The vaccine will help people already being treated for leprosy to improve their outlook and quality of life.
Project Status Timeline
- 2020: Phase 1a complete (USA): LepVax is proven to be safe in healthy adults, which marks the first time the vaccine is successfully tested in people.
- 2026: Manufacturing in queue: This will start once Phase 1b funding is secure.
- 2027: Phase 1b Trial (Brazil): Researchers will conduct an approved study on 54 adults in an endemic area.
- 2029+: Phase 2/3 trials: This is a seven-year trial window.
- ~2038: Vaccine reaches people: Following regulatory approval and WHO prequalification, LepVax will be available for use.
Ultimately, millions of people are affected by leprosy, and stigma and discrimination against the disease taints countries across the globe. The development of LepVax has the power to turn this narrative around.