Fig. 4

Differences in anti-SARS-CoV-2 Spike S1 antibody kinetics between infection-naïve and previously SARS-CoV-2-infected nursing home residents. (a) Increase due to the third vaccine dose, (b) decay after the third vaccine dose, (c) increase due to the fourth vaccine dose, (d) decay after the fourth vaccine dose, and (e) increase due to the fifth vaccine in anti-wild-type (WT) S1 antibodies. (f) Increase in anti-S1 antibodies to Omicron due to the fifth vaccine dose. Decays to one year post vaccine dose five of anti-S1 antibodies against (g) the WT or (h) Omicron SARS-CoV-2. The anti-WT S1 antibody concentrations are expressed in international binding antibody units (BAU) using the 20/136 NIBSC standard and anti-S1 antibody concentrations against Omicron are expressed in arbitrary units (AU). The green line shows the fitted linear mixed effects model (LMEM) of the data from infection-naïve nursing home residents and the red line that from previously infected individuals.Individual data points from males are shown in blue and the female ones in purple. Circles represent individuals of 50–80 years of age, whereas triangles depict persons of 80–100 years of age. Slopes (βi) and number (n) of study participants per timepoint are given within the graphs