Reproduction of antibody levels following five distinct ChAdOx1 nCoV-19 vaccine regimens through virtual patient cohorts.

We present a mathematical model of the immune response elicited by the ChAdOx1 nCoV-19 vaccine across primary and booster immunisations. The model was calibrated with clinical cohort data. To assess population variability, we generated a Virtual Cohort (VC) of >16,000 virtual patients by sampling biologically plausible parameter sets that reproduced observed antibody trajectories. In silico trials compared five adult vaccination scenarios (ages 18-55): a two-dose primary regimen, booster schedules at 8-12, 15-25, and 44-45 weeks, and an additional third-dose option. Model predictions were validated against longitudinal clinical data up to one year after booster administration. Analysis of the VC identified timing strategies for two- and three-dose regimens that promote sustained antibody responses. These results illustrate how computational models and virtual populations can inform vaccine scheduling and support optimisation of vaccination strategies.