Immune response to the HPV-16/18 AS04-adjuvanted vaccine administered as a 2-dose or 3-dose schedule up to 4 years after vaccination: Results from a randomized study

This randomized, partially-blind study (ClinicalTrials.gov registration number NCT00541970) evaluated the immunogenicity and safety of 2-dose (2D) schedules of the HPV-16/18 AS04-adjuvanted vaccine. Results to month (M) 24 have been reported previously and we now report data to M48 focusing on the licensed vaccine formulation (20 μg each of HPV-16 and -18 antigens) administered at M0,6 compared with the standard 3-dose (3D) schedule (M0,1,6). Healthy females (age stratified: 9–14, 15–19, 20–25 years) were randomized to receive 2D at M0,6 (n = 240) or 3D at M0,1,6 (n = 239). In the according-to-protocol immunogenicity cohort, all initially seronegative subjects seroconverted for HPV-16 and -18 antibodies and remained seropositive up to M48. For both HPV-16 and -18, geometric mean antibody titer (GMT) ratios (3D schedule in women aged 15–25 years divided by 2D schedule in girls aged 9–14 years) at M36 and M48 were close to 1, as they were at M7 when non-inferiority was demonstrated. The kinetics of HPV-16, ...