Vaccine Effectiveness and Risk Factors Associated with Measles Among Children Presenting to the Hospitals of Karachi, Pakistan

Objective: To determine the risk factors regarding guardian's practices associated with development of Measles and also find out effectiveness of Measles vaccine among children less than 12 years of age presenting to the hospitals of Karachi. Study Design: Matched case control study. Place and Duration of Study: Multicenter surveillance was conducted in 11 public and private sector hospitals of Karachi from January 2011 to September 2012 in consultation with World Health Organization Measles Surveillance Cell. Methodology: Cases were children aged less than 12 years with Measles presenting to the hospitals. Controls for cases were enrolled from the same hospitals without Measles, matched for age and gender. Studied variables were analyzed by multivariate conditional logistic regression analysis adjusted for age and gender. Results: Measles cases were more likely to have mothers with 'lower education' [adjusted matched Odds Ratio or mOR: 3.2 (95% Cl: 1.2 - 7.6), for < 5 years of schooling adjusted mOR: 2.2 (95% Cl: 1.0 - 5.7) for 6 - 10 years of schooling]. Children with Measles were also more likely to be not given breast milk in initial 2 years of life [adjusted mOR: 2.6, 95% Cl 1.0 - 7.0]. Cases were also more likely to have never received vaccination [adjusted mOR: 10.1, 95% Cl 4.5 - 22.5] and having no other children vaccinated at home [adjusted mOR: 3, 95% Cl 1.5 - 5.3]. Vaccine effectiveness for single dose was found to be 87.4 (95% Cl: 76.1 - 93.4), while for two doses it was approximately 93% (95% Cl: 86.2 - 96.6). Conclusion: For Measles elimination, mother's education on breast feeding and appropriate weaning practices is required.