Delayed dosing intervals for quadrivalent human papillomavirus vaccine do not reduce antibody avidity.

The quadrivalent HPV vaccine (4vHPV) was originally recommended as a three-dose series (0/2/6 months), though delays in completing the series frequently occur. We previously found delayed dosing in girls resulted in similar or higher antibody titers compared to on-time dosing. Archived sera from 262 healthy females aged 9-18 recruited from pediatric clinics were tested to determine if delayed dosing intervals affected antibody avidity. Avidity index (AI; ratio of IgG Ab bound in the treated and untreated sample) was determined pre- and post-dose 3 4vHPV for each participant using a modified multiplex ELISA. Data were grouped by dosing intervals: (1) on-time dose 2 and 3, (2) delayed dose 2 and on-time dose 3, (3) on-time dose 2 and delayed dose 3, (4) delayed dose 2 and 3. Overall, mean AI was highest for HPV16 and lowest for HPV6. As expected, AI did not differ between groups 1 & 3 or groups 2 & 4 pre-dose 3, however, for most types mean AI was significantly higher both pre- and post-dose 3 for groups with delayed dose 2. For all types, mean AI was higher post-dose 3 in all delayed dosing groups compared to group 1. One month post-dose 3, there was a positive but weak correlation between AIs and antibody titer for HPV 6 (ρ = 0.25, p = .0001), HPV 11 (ρ = 0.14, p = .0370), HPV 16 (ρ = 0.11, p = .0934), and HPV 18 (ρ = 0.37, p < .0001). Our findings suggest longer intervals between doses result in higher antibody avidity, providing further evidence that delayed dosing of 4vHPV does not hinder the immune response.

Duke Scholars

Author Emmanuel Benjamin Walter Jr. Pediatrics, General Pediatrics and Adolescent Health