Surveillance of measles antibody levels of middle school students and effect of intensified measles vaccine immunization in junior high school students in Fenghua city

Objective The study was conducted to identify the measles immunization levels and evaluate the effect of intensified immunization of measles vaccine(MV) among junior high school students.Methods A total of 563 participants including students with measles infection history from Xiwu Junior High School and those without infection history from Chunhu Junior and Senior High School in 2005 received the surveillance of measles IgG antibody levels.The students from Chunhu Junior High school were immunized with measles vaccines.Changes of measles IgG antibody levels were recorded before and after intensified inoculation and emergency inoculation of measles vaccines.The measles IgG antibodies were detected by the ELISA technology from intravenously collected blood samples.Results The measles IgG antibody levels were 1001,951 and 813 IU/ml among the students from Xiwu Junior High School(grade one),Chunhu Junior High School and Senior High School,respectively.The geometric mean concentration(GMC) of measles antibodies among Chunhu Junior High School students after inoculation was 2354 IU/ml,2.48 times before inoculation,the protective antibody positive rate being 97.64%.The students from Xiwu Junior High School(grade two and grade three) that received emergency inoculation of MV in 2005 had the GMC of 1889 IU/ml,the protective antibody positive rate 80.61%.Conclusion Junior high school students with intensified or emergency immunization history of MV present an apparently higher measles antibody level compared with those unvaccinated,and the difference is statistically significant.