Fig. 4: Interaction between number of previous exposures and the percent change in IgA and IgG against RBD contrasting the first-vaccinated group minus the first-infected group at T10 and T11*.
* Estimates from linear mixed models estimating the %MFI increase in those first-vaccinated compared to the first-infected group (reference). The models accounted for repeated measurements in the same individual with a random intercept per individual. The model was adjusted as the main model (M5): age (restricted cubic spline with 3 df) + sex + number of chronic comorbidities and tobacco smoking status + number of non-Omicron and Omicron symptomatic infections (as factors) + number of non-Omicron and Omicron asymptomatic infections (as factors) + number of non-bivalent and bivalent vaccines (as factors) + days from last infection (restricted cubic spline with 3 df) + days from last vaccine (restricted cubic spline with 3 df), with an interaction term between the main exposure and number of previous exposures (as a factor). For each isotype and variant of concern model, there were 334 samples from T10 and 306 samples from T11, totaling 640 samples from 354 individuals. The central circles represent the point estimates, and the vertical bars indicate the 95% confidence intervals. Pint represents the two-sided p-value from the likelihood ration test for the interaction term. Source data are provided in the source data. df: degrees of freedom. MFI: median fluorescence intensity. M: model. T: timepoint. RBD: Receptor binding domain.
