ABSTRACT
To determine the Seroprevalence of measles IgG antibodies in school going children [age 4 to7.5 years] and assess the need for second dose of vaccination. Study type, settings and duration: National study in randomly selected primary school children for a duration of 12 months. Subjects and Methods: A national representative sample of 6000 school going children between 5-7 years of age was taken out. As 500 children were already studied an year before in Islamabad, therefore, 2500 children from Punjab, 2000 from Sindh and 500 each from Khyber Pakhtonkhaw and Balochistan making a total of 6000 children. These children were selected from major cities of Pakistan that included Peshawar, Lahore, Multan, Faisalabad, Karachi, Hyderabad, and Quetta. Consent was taken from the parents and principals of the schools for collection of blood samples. About 5 ml of whole blood was taken from which serum was separated and stored for testing. Measles antibody titres [serum IgG antibodies] were measured by enzyme-linked Immunosorbant assay [ELISA]. Antibodies concentration<200 m IU was considered negative [non-protective]; those having levels between 200-300 m IU were labeled as border line and>300 m IU as positive [protective]. For the purpose of analysis, ages of the children were divided into three groups