Seroprevalence of measles antibodies in school going children in Pakistan

To determine the Seroprevalence of measles IgG antibodies in school going children (age 4 to 7.5 years) and assess the need for second dose of vaccination. National study in randomly selected primary school children for a duration of 12 months. 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 300 m IU as positive (protective). For the purpose of analysis, ages of the children were divided into three groups < or equal to 5 years, 5.1-6 years and over 6 years and data compared within provinces. A total of 5503 children were screened for the presence of measles antibodies (IgG). Antibodies were found in 78% children, irrespective of the gender. Age breakup showed that protective antibodies were found in 77.3% children aged up to 5 years, in 76.3% aged between 5.1 - 6.0 years and in 81.1% children aged more than 6 years (p