AN INTERRUPTED TIME SERIES ANALYSIS USING SEGMENTED REGRESSION IN EVALUATING THE EFFICACY OF PCV10 VACCINATION IN KILIFI COUNTY HOSPITAL

Abstract

The study on PCV10 vaccination in Kilifi County is highly relevant for understanding and addressing the burden of pneumonia among children under five. By evaluating vaccine uptake, effectiveness, and challenges, the study provides critical evidence on the role of PCV10 in reducing pneumococcal disease and associated mortality. These findings are essential for informing policy decisions at both county and national levels, particularly in optimizing immunization strategies, resource allocation, and community outreach. The main aim of the study was to develop an ITS model for assessing influence of the PCV10 vaccination intervention, test the developed ITS model viability in relation to correlation structure and use the model in predicting future trend of PCV10 vaccination. The study utilized one time prior to intervention and one period following intervention, segmented regression to account for a separate line segment that is drawn to fit into each period of the independent variable, which is divided into intervals. The variables used in the study were; time before PCV10 vaccination intervention, the PCV10 vaccine and time after PCV10 vaccination intervention. The study population comprised of admissions of children aged between two months and five years admitted to Kilifi County Hospital from January 2007 to December 2020. The study findings indicated a downward trajectory as regards the number of pneumonia cases reported. Further, segmented regression results showed that the intercept (β0) = 823.16, coefficient estimate of time (β1) = - 2.72, coefficient estimate of PCV10 intervention (β2) = 59.63 and the coefficient estimate of the time after PCV10 intervention (β3) = -6.03. In addition, the results exhibited that in the period after the intervention, the number of pneumonia cases had an average value of approximately 422.02. The drop in the number of pneumonia cases observed in the PCV10 intervention period is therefore statistically significant. The study concludes that the developed model is effective in assessing influence of the PCV10 vaccination intervention and able to predict future trend of pneumonia infections in Kilifi County. The study findings are instrumental towards the development of strategies and policies aimed at improving longevity and overall health among Kilifi County residents. The model will guide towards effective allocation of preventive healthcare resources to alleviate pneumonia transmission in Kilifi County.