There were a total of 44 subjects (qHPV, 24; placebo, 20) with available mother-infant pair serology data whose data were considered for the antibody analysis. In general, the serum samples obtained at the time of infant delivery from mothers given placebo were seronegative for vaccine-type anti-HPV. There were only 4 mothers who received placebo whose serum samples obtained at the time of infant delivery were seropositive for HPV-6.
Among the subjects whose mother-infant pairs were used in the correlation analysis, the median time after vaccine dose 3 when the maternal serum and cord blood samples were obtained was 28 months (range, 14 to 43 months; interquartile range, 19 to 35 months). Relative to day 1, the median time after vaccine dose 1 when the maternal serum and cord blood samples were obtained was 34 months (range, 19 to 48 months; interquartile range, 24 to 40 months).
As seen in , the majority of infants whose mothers received qHPV vaccine and were seropositive for a vaccine HPV type were also seropositive for that HPV type. Overall, 67%, 83%, 92%, and 39% of infants were seropositive via the cLIA assay to HPV types 6, 11, 16, and 18, respectively, when their mothers were also seropositive at the time of birth. When all HPV-specific IgG molecules are considered, 84%, 65%, 100%, and 62% of infants were seropositive for HPV-6, -11, -16, and -18, respectively, when their mothers were also seropositive at the time of birth.
Summary of serostatus of mother-infant pairs (all mother-infant pairs with serology data)a
shows the scatter plot on the 2-dimensional xy plane of the HPV cLIA data points (x = cord blood anti-HPV result, y = maternal serum anti-HPV result) for each of HPV types 6, 11, 16, and 18. The data indicate that HPV titers in maternal serum samples are positively correlated with anti-HPV titers from infant cord blood samples. Pearson correlation coefficients of 0.94, 0.83, 0.80, and >0.99 were calculated for HPV-6, -11, -16, and -18, respectively.
Scatter plots of mother-infant vaccine-type anti-HPV titers (all qHPV vaccinated with mother-infant serology result). The analysis of HPV-6 includes 4 mother-infant pairs such that the mother received placebo but had detectable anti-HPV-6.
A plot of the distribution of the ratios of infant to mother cLIA anti-HPV results for each of the 4 vaccine HPV types is shown in . The distribution of the ratio of anti-HPV results centered on 1.0 further illustrates the highly concordant mother and infant anti-HPV antibody titers.
Fig 2 Distribution of the ratios of infant to mother anti-HPV titers (all qHPV vaccinated with mother-infant serology result). The bottom and top edges of the box plot correspond to the 25th and 75th percentiles, respectively, of the distribution. The horizontal (more ...)