Assessment of Factors Associated with Low Measles Vaccine Effectiveness in Honkolo-Wabe District, Ethiopia

Background:-Measles is an acute illness and the most contagious childhood diseases. Almost all non-immune children contract this respiratory disease if exposed to the virus. The disease characterized by prodarmal fever, conjunctivitis, coryza and presence of Koplik spots. Prior to the introduction of vaccination programs, measles affected almost every child in the world. The expected sero conversion was estimated to 80-85% when 0.5ml live attenuated measles vaccine correctly administered subcutaneously at 9 months and more than 95% after 12months. This study was aimed to describe vaccine effectiveness and assess factors contributing to low measles vaccine effectiveness in Honkolo-Wabe district, Ethiopia. Methods:-Community based unmatched case-control study, involving 51 children who had previous measles illness were randomly selected and 153 controls were selected from the community three for each case in July, 2014. Vaccination status and other risk factors for the study children were ascertained through by interviewing mothers /care giver and observing the cold chain management. Epi-info version 7 was used for data analysis. Results:-Measles vaccine effectiveness was estimated at 70.9% [95% CI=65-79%]. Age of measles vaccine given, poor health seeking behavior of the community, number of dose and inappropriate vaccine transportation from district health office to health post, administration of reconstituted vaccine after 6hrs by HEW were identified as the contributing factors for low measles vaccine effectiveness in Honkolo-Wabe district. Contacting with laboratory confirmed or epidemiological linked measles cases statically significant regard to measles [OR=23.77, 95% CI=9.17-64.25]. Of the study participants 19.6%, 44.6% and 3.9% were received one, two and three doses of measles vaccine respectively. About 3.9%, 45.1% and 12.3% of the participants were received first dose of measles vaccination before, at 9month and after nine month respectively. However 18.6% of the study participants were not received 2nd does. Only 35.3% of the participants were received their second doses after 12month their birth. Conclusions:-Measles vaccine effectiveness was low. Age of children, number of dose, inappropriate vaccine transportation and utilization of reconstituted vaccine after 6hrs were contributing factors for low measles vaccine effectiveness. Regular monitoring and ensure of all birth cohort have received at least 2 doses of measles vaccine at 9month of their birth and above. Improve cold chain management at health post and use reconstituted vaccine within 6 hours.