Figure 2. Human Papillomavirus (HPV)–Type-Specific Antibody Response to Quadrivalent Vaccine by Study Cohort Over Time, Measured by Enzyme-linked Immunosorbent Assay.

A, HPV-6. B, HPV-11. C, HPV-16. D, HPV-18. Geometric mean antibody levels with geometric SDs were plotted at day 1 (prevaccine baseline) and months 2, 6, 7, and 12 after the first vaccination. The blue circles represent hematopoietic stem cell transplant participants (HCT) receiving immunosuppression therapy (IST), the orange squares represent HCT not receiving IST, and the grey triangles represent healthy volunteers. Levels lower than the cutoff were given the value of 4 EU/mL.