Leprosy, a chronic
infectious disease caused by Mycobacterium leprae and Mycobacterium
lepromatosis, remains a major public health challenge today. Despite
advancements in treatment through multidrug therapy (MDT), the persistence of
the disease, active transmission cases, and associated stigma continue to
hinder eradication efforts. In this context, prophylactic and therapeutic
vaccines are emerging as promising tools, offering a critical complementary
approach to accelerate the elimination of this ancient disease.
Leprosy Vaccines: A
Promising Strategy?
This study reviewed 12
randomized clinical trials assessing the efficacy of leprosy vaccines, divided
into 8 prophylactic and 4 therapeutic studies. Key findings include:
Prophylactic
Vaccines:
- A significant reduction in infection risk
was observed, with a combined relative risk of 0.61.
- Vaccines based on BCG, alone or combined
with other components (e.g., Mycobacterium indicus pranii), showed varying
protective effects depending on the populations studied (age, region).
Worth noting: Relative risk compares the
likelihood of an event (such as disease) between two groups, indicating how
many times higher or lower the risk is in one group versus another.
Therapeutic
Vaccines:
- Clinical severity scores, such as the Ramu
score, significantly improved after administering therapeutic vaccines
like Mycobacterium w.
- However, results on the bacterial index
were inconsistent, suggesting a limited impact on active bacterial load.
Worth noting: The Ramu score is a clinical tool
used to evaluate the severity of leprosy, considering criteria such as skin
lesions, affected nerves, and internal organ involvement.
Promising Vaccines
to Close a Millennia-Old Chapter
The findings indicate
that leprosy vaccines, whether prophylactic or therapeutic, provide significant
protection and improve clinical outcomes. However, the heterogeneity of
studies, particularly in vaccination protocols and control groups, limits the
generalization of conclusions.
