Code and data for the underlying model outlined in the "Real-time estimation of immunological responses against emerging SARS-CoV-2 variants". The underlying antibody kinetics model is written in Stan. We use cmdstan, called from R using the cmdstanr package. We use data.table for our data manipulation throughout and ggplot2 for all plots. Lastly, for extracting the posterior samples in a user-friendly and simple manner, we ubiquitously use the tidybayes package.