Consistent with established risk factors for severe CRS reported in prior studies [14, 15], we operationalized ANC as a binary variable (neutropenic [ANC < 0.5 × 109/L] non-neutropenic) and IL-6 level as a dichotomized parameter (≥ 150 pg/mL vs. < 150 pg/mL). This evidence concerns the gene IL6 and congenital rubella syndrome.