Post-Vaccination Antibody Persistence and Immune Response Variability in East Mediterranean Children Following Measles-Rubella Vaccination Campaign (2022–2024)
Carlos Martín¹, Lucia González², Javier Ortega³, Sofia Hernández⁴, Elena Torres⁵
Keywords:
measles, rubella, vaccine immunity, antibody persistence, pediatric immunizationAbstract
Despite large-scale immunization efforts, periodic outbreaks of measles and rubella persist in the East Mediterranean region, raising concerns about the long-term durability of vaccine-induced immunity. This prospective study evaluated antibody persistence and immune response variability in 1,204 children (ages 9 months to 6 years) across Egypt, Jordan, and Iraq following national measles-rubella (MR) vaccination campaigns conducted between 2022 and 2024.
Children were stratified into three age groups: 9–12 months (n = 408), 13–36 months (n = 412), and 37–72 months (n = 384). Serum IgG titers were measured at 6, 12, and 18 months post-vaccination. At 18 months post-vaccination, 89.3% retained protective measles IgG levels (>200 mIU/mL), while only 74.8% maintained rubella IgG above the protective threshold (>10 IU/mL). Antibody waning was significantly higher in the youngest group, with a 27.4% drop in rubella IgG levels between 6 and 18 months (p < 0.001).
Host immune profiling revealed that children with HLA-DRB1*15:01 genotype had 2.1-fold higher rubella IgG decline compared to non-carriers (p = 0.004). Additionally, malnourished children had significantly lower peak antibody levels and a faster rate of waning (p < 0.001). Multivariate logistic regression identified age at vaccination, nutritional status, and genetic polymorphism as independent predictors of seroprotection at 18 months.
Overall, 16.7% of participants fell below protective levels for either measles or rubella by 18 months, highlighting potential gaps in immunity. These findings support the need for age-specific booster policies and underline the importance of post-campaign immunological surveillance.
This is the first longitudinal immunogenicity study in East Mediterranean children linking genetic and nutritional factors to MR vaccine antibody durability, with direct implications for improving public health immunization strategies.
