Fig. 2. Effect of age on the avidity of HPV-specific antibodies.

a Avidity of HPV-6, HPV-11, HPV-16, and HPV-18-specific specific IgG, measured in a subgroup of ELISA responders, reported as molarity (M). Each dot represents a single donor; n = 11 and n = 10 for adolescents of the “Early cohort” and the “Late cohort”, respectively; n = 8 and n = 9 for adults of the “Early cohort” and the “Late cohort”, respectively. b Molarity values (M) were correlated with with the months post-vaccination. Statistical significance was determined by the Mann–Whitney (a) and Spearman’s rank correlation (b) and all p-values are shown. “Early cohort”, Early; “Late cohort”, Late.