MEASLES SEROPREVALENCE IN SCHOOL GOING AGE CHILDREN

ABSTRACT

Objectives:The aim of the study was to determine the IgG antibodies against measles in school going children and assess the need of second dose of vaccination. 

Methods:A national representative sample of 5503 school going children between 5-7 years of age was taken out using the prevalence rate of 14.9 % and 5% level of significance. These children were selected from major cities of Pakistan comprising of 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 and serum separated and stored for testing. Measles antibody titres (serum IgG antibodies) were measured by enzyme-linked immunosorbent assay (ELISA). For the purpose of analysis, ages of the children were divided into < or equal to 5 years, 5.1-6 years and over 6 years and results are reported for the country and province wise.  

Results:A total of 5503 children were screened for the presence of measles antibodies. Protective IgG antibodies were found in 78% children. Gender wise 77.9% males and 78.0% females had antibodies. 

Age breakup showed that these 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, antibodies were significantly higher in Sindh (82.9%) and Balochistan (80.4%) as compared to Punjab (74.3%) and NWFP (75.2%) (p<0.01), and a similar trend was seen in gender within the provinces.  

Province and age wise breakup showed that antibody titers in children up to 5 years of age were present in 80.8% in Sindh, 86.7% in NWFP and 81.5% in Balochistan but were significantly less (73.4%) in Punjab (p<0.05). In children between 5.1-6.0 years antibody positivity was 80.9% Sindh and 79% in Balochistan but was significantly less in Punjab (73.1%) and NWFP (74.1%) (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:About 20% children are unprotected against measles. Strategies need to be developed to scale up this protection.