Safety & Immunogenicity of a Candidate Vaccine for Visceral Leishmaniasis (Alum-Precipitated Autoclaved L.Major +BCG) In Children: An Extended Phase II Study. Annals of Tropical Paediatrics

Khalil, Eltahir Awad G; Musa, Ahmed M.

Safety & Immunogenicity of a Candidate Vaccine for Visceral Leishmaniasis (Alum-Precipitated Autoclaved L.Major +BCG) In Children: An Extended Phase II Study. Annals of Tropical Paediatrics

Date

2015-11-25

Authors

Khalil, Eltahir Awad G

Musa, Ahmed M.

Publisher

UOFK

Abstract

Background: Untreated visceral leishmaniasis (VL) is an inevitably fatal childhood disease. First-generation candidate vaccines for VL [autoclaved Leishmania major (ALM) + BCG] have been found to be safe and immunogenic but not superior to BCG alone. Modulation of ALM by adsorption to Alum significantly increases the immunogenicity. The Alum-adsorbed ALM vaccine was found to be safe and strongly immunogenic in healthy adult volunteers in a non-VL-endemic area. This study aimed at establishing the safety and immunogenicity of Alum-precipitated autoclaved L. major + BCG vaccine in children under field conditions. Methods: A total of 544 healthy, leishmanin non-reactive children (<15 y) were randomly allocated to receive either a single intradermal injection of Alum/ALM + BCG or vaccine diluent (placebo). Volunteers were closely followed for 2 years at 6-month intervals for vaccine safety and immunogenicity. Results: The vaccine was well tolerated with minimal side-effects. Leishmanin skin test conversion (≥5 mm) was seen in 56%, 50%, 25% and 31% at 6, 12, 18 and 24 months post-vaccination, respectively; conversion in the placebo group was 4%, 12%, 3% and 13% at the same follow-up visits. There was no significant increase in anti-leishmanial antibodies in either study arm at any of the follow-up visits. During the study, four patients in the placebo arm developed parasitologically confirmed VL. Conclusion: Alum/ALM + BCG vaccine is safe and immunogenic in children under field conditions. Multiple injections might be needed to obtain results similar to those obtained in healthy volunteers.