Figure 3.

Correlations of antibody titers (A) one month after SVD and three weeks after FVD, (B) one month after BD and nine months after SVD, (C) six months after SVD and one month after SVD, (D) six months after BD and one month after BD. Points corresponding to IgG titers after primovaccination are coloured blue; points corresponding to IgG titers after the BD are coloured red. Titers were logarithmically transformed before plotting to ensure better visualisation. Sera after contracting COVID-19 were not included. FVD = first vaccine dose, SVD = second vaccine dose, BD = booster dose, r = Spearman’s correlation coefficient. *** p < 0.001 (correlation test).