Individual-level reconstruction of longitudinal anti-spike binding antibody kinetics under hybrid immunity
摘要
Reconstructing individual-level antibody dynamics from sparse and irregularly sampled serological data remains challenging, particularly under hybrid immunity shaped by repeated vaccination and infection. We developed a trajectory reconstruction framework that integrates a piecewise exponential kinetic model with a nonlinear mixed-effects approach to infer event-specific antibody kinetics from longitudinal real-world data. The model represents each individual’s anti-Spike binding antibody response as a continuous sequence of boosting and waning phases across primary vaccination, second dose, booster vaccination, and breakthrough infection, while jointly estimating population-level typical kinetics and subject-specific deviations. We applied the framework to longitudinal antibody measurements from 380 healthcare workers in South Korea with heterogeneous sampling schedules, vaccine regimens, and immune histories. The framework enabled reconstruction of individual antibody trajectories from irregular observations, with a median individual-level Standardized Root Mean Square Error (SRMSE) calculated on the