Sero-surveillance of measles amongst vaccinated and non-vaccinated children: An age stratified population based survey in Pakistan

Measles is one of the most contagious human diseases; it remains a leading cause of death among young children and its elimination is one of the major global public health priorities. It is estimated that in year 2008 approximately 100,000 deaths in children aged less than 5 years was attributable to measles. The increase in measles vaccination coverage in the developing world has produced significant changes in the epidemiology of the infection. The present age stratified cross sectional survey was conducted in Islamabad, Pakistan and its adjoining areas during January to June, 2009 to determine the measles protective titre in children of 1 to 15 years. 927 blood samples of children were collected to ascertain the measles antibodies by ELISA assay. 588 were males and 339 were female (p = 0.001). Measles IgG antibodies sero-positive ratio in children among examined population was 741 (79.9%), sero-negative 174 (18.77%) (p = 0.001). Out of 174 seronegative children, 135 (14.5%) were vaccinated while 39 (4.20%) children were non-vaccinated. The children were divided into three groups, that is, 1 to 5 years (pre school age), 6 to 10 years (primary school group) and 11 to 15 years (secondary school going children). Sero-positive antibodies percentage increased age. Measles IgG antibodies ratio is higher in male children as compared to female. Sero-surveillances should be conducted at regional and provincial levels to assess the actual level of protective titre throughout the country and to evaluate the country's vaccination program. The routine coverage of immunization should also increase from 80 to 100%.