Meningococcal vaccines and protein-energy undernutrition in children in the African meningitis belt.

BACKGROUND: Vaccines to prevent meningococcal meningitis in the African meningitis belt include PsACWY, a polysaccharide-only vaccine; and PsA-TT, a polysaccharide-protein conjugate vaccine. Protein-energy undernutrition, a condition where children do not receive enough macro- or micronutrients, is related to increased risk of infectious diseases and poor immune function. Reduced immune function could affect vaccine immunogenicity. We investigated connections between protein-energy undernutrition and vaccine immunogenicity and antibody waning to PsACWY and PsA-TT in children in the African meningitis belt. METHODS: This is a secondary analysis of data collected as part of four clinical trials testing the safety and efficacy of PsA-TT in children in Mali, Ghana, and Senegal. We identified whether anthropometric growth indices (low height-for-age, weight-for-height, or weight-for-age Z-score categories) were related to reduced vaccine-elicited antibody (measured with rabbit complement) from pre- to 1 month post-vaccination, in linear regression models. We also identified whether these growth indices were related to increased waning for vaccine-elicited antibody over time, in linear regression models. RESULTS: A total of 697 children were included in our analysis, of which 350 (50.2%) were female; the mean (SD) age was 1.0 (1.1) years, and 578 (83.0%) received PsA-TT. In linear regression models, no consistent statistical relationship was seen between pre-vaccination anthropometric Z-score categories and vaccine immunogenicity, or decline in antibody over time, for either vaccine, although children with low weight-for-height had a greater decline in antibody from 1 to 6 months post-vaccination. CONCLUSIONS: Our analysis did not find protein-energy undernutrition to be associated with immunogenicity or waning of PsACWY- or PsA-TT-elicited antibody in children living in the African meningitis belt. Future studies should consider measuring antibody titers at additional time points post-vaccination, and for longer periods of time, to determine if the rate of antibody waning over a period of several years is associated with protein-energy undernutrition.