COVID-19 vaccine fatigue in Scotland: how do the trends in attrition rates for the second and third doses differ by age, sex, and council area?

Vaccine fatigue is the propensity for individuals to start but not finish a vaccination program with several doses, which means they are less protected. Our study examines vaccine fatigue in the COVID-19 vaccination programme in Scotland. We model the attrition rates across multiple doses with a hierarchical binomial logistic regression model with correlated age- and area-specific random effects with conditional autoregressive priors, where inference uses integrated nested Laplace approximations. We find attrition rates smoothly decrease with increasing age, are much higher for the third dose than the second, and are generally higher for males than females.