Immune characteristics of the study subjects.

aValues reported are in IU/mL for antibody responses, cytokine spot-forming units (SFUs) per 2×105 cells for Elispot responses and pg/mL for secreted cytokines ± IQR, inter-quartile range with 25% and 75% quartiles.Elispot response and secreted cytokine response is defined as the subject-specific median rubella virus-stimulated response (measured in triplicates) minus the median unstimulated response (also in triplicates). Negative values indicate that stimulated values were on average smaller than unstimulated values.bP-value from multivariate analysis, statistically adjusting for all other variables (age at enrollment, age at first and second immunization, time since second rubella immunization to blood draw).