Measles antibody in previously two dose immunized and reimmunized in school age children

Background: The aim of this study was to determine measles antibody titer in children who received two doses of vaccine and were reimmunized at 7 years of age. Methods: The school children were randomly choosen from various areas of Tehran who had received two doses of measles vaccine at 9 and 15 months of age and reimmunized at 7 years of age. Measles antibody was measured in children aged 7 years and 4-6 weeks after reimmunization by Enzyme-linked immunosorbent assay (ELISA). Findings: A total of 339 children were evaluated. Antibody titers in 132 (38.9%) children were more than 10 IU/ml (mean 68.3 IU/ml) and 207 (61.1%) less than 10 IU/ml. Antibody titers in 32 of 42 children who had been reimmunized were less than 10 IU/ml. In two (6.3%) of 32 children antibody titers did not rise after reimmunization and the mean antibody titer in remainder (30) of the children was 71.3 IU/ml. Antibody titers in 10 (23.8%) of 42 children before and after reimmunization were 58 and 168.5 IU/ml respectively. After reimmunization, the mean antibody titer in children with high titer before reimmunization was higher than those with low antibody titer. Conclusion: This study indicates that children with two dose measles immunization before and after the first year of age are still immunologically resistant against measles at 7 years of age. Immunization is the most efficacious and cost effective intervention available to improve the health and wellbeing of children and prevention of the infectious disease.