Effectiveness of Measles Mass Vaccination in the Reduction of Childhood Morbidity and Mortality in Yobe State, Northeast Nigeria

Abstract

Measles is an issue of public health concern responsible for outbreaks and death of children especially in Sub-Saharan Africa. This study sought to determine the effectiveness of mass vaccination against measles in Yobe State, Northeast Nigeria. An ecological epidemiological study design involving the collection of secondary data from the same population was carried out over a period of two years. These data were collected from Epidemiology Unit of Yobe State Primary Healthcare Development Board from the Integrated Disease Surveillance Response database which collects records of notifiable diseases in Nigeria. All cases of measles within the period under review (2016-2017) were included and a comparison of the number of cases and deaths from measles reported in two different periods before supplementary immunization activity or mass vaccination against measles (2016) and after supplementary immunization activity against measles in the state (2017) was done. The mass vaccination intervention was conducted within first week of January 2017 as a measure to address outbreaks of measles in the state. Data were analyzed using the Statistical Package for Social Sciences (SPSS) windows version 22. A total of 4242 cases were reported during the study period. 3780(89.1%) in 2016 (before mass vaccination) and 462(10.9%) were reported in 2017 (after mass vaccination). A total of 556 deaths with case fatality rate of 13.1% was recorded during the study period. Majority of the deaths 525(94.4%) occurred in 2016 when there was no mass vaccination while few 31(5.6%) occurred in 2017 after the mass vaccination. Mass vaccination resulted in a 78.2% decline in number of cases and 88.8% decline in the number of deaths from measles. There was a statistical significant difference in the number of cases and mortality from measles pre and post mass vaccination against the disease in Yobe state. Paired sample t-test done revealed a monthly case distribution mean of 276.6 (95% CI 89.8 to 463.3) with alpha set at 0.05, P = 0.008 while monthly mortality mean was 41.1 (95% CI 15.5 to 66.7) with alpha set at 0.05, P = 0.005. Mass vaccination against measles therefore confers immunity and herd immunity to populations with a subsequent significant decline in morbidity and mortality associated with the measles infection. It is therefore recommended that this initiative be sustained for every two years or possibly yearly to ensure elimination of measles in the Sub-Saharan Africa region and the World at large.