Sadaruddin A, Ghafoor F, Alam S E, Sumera Naz, Khan I M, Mohyuddin G, Shahid A, Taseer I, Habibullah S, Akhtar T, Iqbal R, Goraya A, Talreja K, Arif A.
Seroprevalence of measles antibodies in school going children in Pakistan.
Pak J Med Res Jan ;51(2):38-43.
Objectives: 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 < or equal to 5 years, 5.1-6 years and over 6 years and data compared within provinces. Results: 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<0.01). Within the provinces, titers of protective antibodies were significantly higher in Sindh (82.9%) and Balochistan (80.4%) as compared to Khyber Pakhtonkhaw (75.2%) and Punjab (74.3%) (p<0.01), and a similar trend was seen for gender within the provinces. Province and age wise breakup showed that antibody titers in children up to 5 years of age were present in 86.7% in NWFP, 81.5% in Baluchistan, 80.8% in Sindh, but were significantly low (73.4%) in Punjab (p<0.05). In children between 5.1-6.0 years antibody positivity was 80.9% in Sindh, 79% in Balochistan, 74% NWFP and again were significantly low in Punjab (73.1%), (p<0.05). In children over 6 years of age, higher antibody positivity was seen in Sindh (85.3%) and Balochistan (90.3%) and significantly less were found in Punjab (76.9%) and NWFP 73.9% (p<0.05). Conclusions: Overall about 22% children are unprotected against measles. Within provinces Punjab is showing less protection as compared to other provinces. Strategies need to be developed to scale up this protection. Policy message: Expanded program of immunization should review its strategies for measles immunization and look for introducing a second dose of vaccine.
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