A systematic review and modelling insights of factors impacting measles vaccine effectiveness

IntroductionOutbreaks of measles have been frequently reported despite the availability of an effective vaccine. In this systematic review we examine the potential factors that could impact the effectiveness of the measles vaccine (MV) in children. MethodsWe conducted a literature search using PubMed and Google Scholar for primary articles published between January 2014 and July 2024. Articles reporting the effectiveness or immunogenicity of MV in children aged 0-15 years were included. Additionally, we use regression analysis on data available from few cohort studies in India and epidemiological modelling simulations to assess the effect of factors on vaccine effectiveness (VE). ResultsOverall, 34 primary articles involving 151888 children who had received the MV were included in the analysis. Key factors that may affect VE were malnutrition, genetic variants, chemotherapy and gender. Through statistical modelling we identified an inverse relationship between malnutrition and measles VE and estimated the possible percentage decrease in VE due to malnutrition across different states of India. Additionally, simulations from a Susceptible-Infected type model showed the effect of varying VE on the modelling outcomes and measles elimination targets. ConclusionsWe identified a few key factors including malnutrition, genetic variants, chemotherapy and gender that impact measles VE. Therefore, in addition to maintaining WHO recommended vaccine coverages, addressing the problems related to VE is crucial for achieving measles elimination targets.