Fig. 3.

Human papillomavirus type-specific IgG antibody concentrations before first (pre) and 3 months after last vaccination (post).

(a) qHPV group; (b) placebo group. Units: LU/ml. Gray horizontal solid bars represent geometric mean concentrations. Dotted horizontal line/seropos: seropositivity thresholds: 6 LU/ml (HPV16), 7 LU/ml (HPV18). HPV, human papillomavirus; IgG, Immunoglobulin; LU/ml, Luminex units per ml; qHPV, quadrivalent HPV vaccine. ^∗P less than 0.001; NS, nonsignificant (P > 0.10; paired t test).