Pre- vaccination seroprevalence of rubella IgM among women of child bearing age in southeast Nigeria: a five-year cross-sectional study.

Rubella is an acute, contagious viral illness that is generally mild, yet infection during early pregnancy can cause congenital rubella syndrome (CRS), a serious condition associated with deafness, blindness, congenital heart defects, and developmental disabilities. Although vaccination is the only effective preventive measure, rubella continues to circulate in regions with low immunization coverage. This study assessed the pre-vaccination seroprevalence of rubella IgM antibodies among women of reproductive age in Southeast Nigeria. A retrospective cross-sectional study was conducted from 2020 to 2024 among 405 women aged 15-49 years across five states in Southeast Nigeria. Serum samples were tested for rubella IgM antibodies using ELISA. Rubella IgM seroprevalence was 6.7% (27/405). Adolescents, 15-19 years had the highest positivity (11.7%), with prevalence declining steadily with age to 1.9% among women aged 30-34 years. Rubella positivity peaked in 2020 (16.0%) and 2024 (14.5%), with Imo State showing the highest prevalence (10.1%) and an incidence of 7.3 per 1,000,000 population. Rubella IgM positivity among women of childbearing age indicates ongoing transmission and susceptibility, particularly among adolescents. These findings provide baseline data for assessing vaccine impact and highlight the need for stronger surveillance and improved uptake to prevent CRS in Nigeria.