Mean ±Standard Error in the Mean (SEM) IgG titers for the measles vaccines sourced from "Open Market", Ebonyi, Enugu, Imo, Anambra and Abia States were 0.793±0.051, 1.621±0.015, 1.621±0.015, 1.715±0.081, 1.793±0.051 and 1.683±0.078 respectively while the mean ±Standard Error in the Mean (SEM) IgM titres were 0.857±0.037, 1.400±0.030, 1.391±0.032, 1.339±0.037, 1.405±0.066 and 1.279±0.025 respectively. The gene discussed is CD40LG; the disease is measles.