This study examined the factors influencing vaccine uptake using the Fogg Behavioral Model (FBM) and validated a multi-dimensional index for measuring a key construct in the FBM, motivation, using Confirmatory Factor Analysis (CFA) and Cronbach's alpha. The research was conducted in Yopougon Est, Côte d'Ivoire, and Kinshasa, Democratic Republic of Congo. We aimed to develop a motivation index for COVID-19 vaccination uptake informed by the FBM. The motivation index was developed and refined using interviews and cognitive testing, and then used in baseline and endline surveys to measure the motivation to uptake COVID-19 vaccination among 2173 respondents. The index was simplified to six items validated using Confirmatory Factor Analysis (CFA) and demonstrated strong internal reliability with Cronbach's alphas of 0.89 for the baseline and 0.77 for the endline. The study's findings indicate that this motivation index is a valid tool for measuring motivation to receive COVID-19 vaccination, with potential applications in other vaccination campaigns. However, further testing in diverse settings is needed to enhance generalizability, including in rural areas. This research provides valuable insights for designing effective behavior change interventions to increase COVID-19 vaccination rates.
Keywords: COVID-19 vaccination; Fogg Behavioral Model; behavior change interventions; confirmatory factor analysis; demand creation; motivation index; vaccine hesitancy.