Background: This exploratory analysis was conducted to characterize the level of HPV types 6/11 antibodies in peripartum maternal blood and in cord blood of infants born to women who received 9-valent HPV (9vHPV) vaccine or quadrivalent HPV (qHPV) vaccine in a pivotal efficacy study (V503-001, NCT 00543543).
Methods: A total of 21 mother-infant pairs had evaluable HPV 6/11 results available for analysis. HPV6/11 antibodies were assessed using competitive Luminex immunoassay. The distribution of the ratios of infant to mother anti-HPV antibodies (i.e., infant-anti-HPV/mother- anti-HPV) was summarized.
Results: All mothers and infants were seropositive to HPV 6 and HPV 11. Anti-HPV 6/11 geometric mean titers (GMTs) in peripartum maternal blood and in cord blood of infant born to study participants were highly correlated. A 100% of infants born to seropositive mothers were also seropositive. The GMT ratios of peripartum maternal blood vs. those in cord blood were HPV 6: 1.23 [0.43, 3.49] and HPV 11: 1.29 [0.54, 3.07] in the 9vHPV vaccine group and HPV 6: 1.33 [0.41, 4.29] and HPV 11: 1.19 [0.45, 3.13] in the qHPV vaccine group, respectively.
Conclusions: These results indicate that antibodies induced by the 9vHPV vaccine cross the placenta, which could potentially be beneficial against HPV6/11 infection and related disease such as recurrent respiratory papillomatosis.
Keywords: 9vHPV vaccine; clinical trial; geometric mean titers (GMTs); human papillomavirus; recurrent respiratory papillomatosis.