When considering the severity of CRS as continuous variable, the levels of pre-infusion serum IL-6 (Spearman r = 0.241, P = .0117) and ferritin (Spearman r = 0.2, P = .0369) were positively correlated with the grade of CRS, no correlation was found between CRP concentration and CRS grade (Figures 4A–C). This evidence concerns the gene IL6 and congenital rubella syndrome.