(A) Trajectory of Spike RBD IgG antibody titres and incidence rate in the Tyrolean population during the course of this study. (B) Trajectory of Spike RBD IgG antibody titres and % vaccinated in the Tyrolean population during the course of this study. The analysis involved data on 35,800 Spike RBD IgG antibody measurements taken from 27,845 seropositive participants. Data on SARS-CoV-2 infections and SARS-CoV-2 vaccinations in the Federal State of Tyrol, Austria, are publicly available at the AGES webpage. Abbreviations: BAU/mL, Binding Antibody Units per millilitre; CI, confidence interval; GM, geometric mean; RBD, receptor-binding domain.