Table 3.

Results of regression models with post vaccination titer T_post as the dependent variable in every case.^{^}

Variables	Estimates of regression model		Variables	Estimates of regression model
			Nr vaccinations	A (y-intercept)	3.738^*
				B_NV	−0.369^*
				R²	0.039
Pre-titre	A (y-intercept)	2.433^*	Pre-titre	A (y-intercept)	2.777^*
Pre-titre	B_pre	0.600^*	Pre-titre	B_pre	0.642^*
			Nr vaccinations	B_NV	−0.502^*
	R²	0.257	Nr vaccinations	R²	0.327
Pre-titre Age group	A (y-intercept)	2.993	Pre-titre Age group	A (y-intercept)	3.248^*
	B_pre	0.592^*		B_pre	0.692^*
	B_agegroup	−1.006^*		B_agegroup	−0.911^*
			Nr vaccinations	B_NV	−0.448^*
	R²	0.335	Nr vaccinations	R²	0.390

^{^}

The regression models on the right include number of previous vaccinations B_NV. Notice that number of previous vaccinations has a statistically significant negative effect and contributes to the R² in every case.

p<0.001