Immunotherapeutic effect of MIP vaccine along with multidrug therapy (MDT) in leprosy: A systematic review and meta-analysis.

Background and objectives Leprosy is a neglected tropical disease caused by Mycobacterium leprae often resulting in nerve damage, numbness, disfiguring lesions, and disability. India accounts for ∼52% of the world's new leprosy patients. Immunotherapy has been reported to achieve faster bacterial clearance in multi-bacillary (MB) leprosy patients. We conducted this systematic review to synthesise the global evidence available for the efficacy and safety of the MIP vaccine (Mycobacterium indicus pranii), previously known as Mw, as an immunotherapeutic agent along with standard chemotherapy, on the treatment outcomes in patients with multi-bacillary (MB) and pauci-bacillary (PB) leprosy. Methods Three bibliographic databases namely, PubMed, Embase, and Cochrane Library were used for search of articles apart from four clinical trial registries, Google Scholar, and the Google search engine. Articles published between 1980 to 2023 reporting the efficacy of the MIP vaccine for immunotherapy along with standard chemotherapy in leprosy patients were included. Methodological bias was assessed using the RoB2 and ROBIN-I tool. Meta-analysis was carried out from four RCTs and three non-RCTs for the outcomes clinical score and bacterial index following 12 and 24 mo of treatment using the Review Manager 5.4.1 (RevMan). Results The pooled analysis of four RCTs with 12 and 24 mo of follow up showed a significant reduction in clinical scores with mean difference of -1.35 [95% confidence interval (CI): -2.12 to -0.57] and -2.62 (95% CI: -4.28 to -0.96) respectively, while the analysis of three non-RCTs showed a mean difference of -2.97 (95% CI: -4.00 to -1.94) and -3.10 (95% CI: -3.84 to -2.37) at 12 and 24 mo respectively. Subgroup analysis showed a significant reduction in clinical scores and bacterial index among borderline lepromatous (BL) and lepromatous leprosy (LL) types of leprosy. The vaccine was reported to be safe and well-tolerated. Interpretation and conclusions This systematic review and meta-analysis confirms the clinical efficacy of the MIP as an immunotherapeutic vaccine in leprosy patients for rapid bacterial clearance and overall clinical improvement when used as an adjunct to chemotherapy.