Table 2.

Month 7 and 12 neutralizing antibody responses as geometric mean titers (GMTs) and seroconversion rates (SCR) in the iPPS.^a.

Antibody	Population	Placebo group				Vaccine group				p values#
		N	Seroconverted n (%)	GMT (95%CI)		N	Seroconverted n (%)	GMT (95%CI)		SCR*	GMTs
Month 7
HPV16	All participants	532	21 (4.0)	20.7	(20.4, 21.1)	504	503 (99.8)	5827	(5249, 6468)	< .001	< .001
	9–17 years	275	4 (1.5)	20.2	(20.0, 20.4)	265	264 (99.6)	8571	(7437, 9879)	< .001	< .001
	18–26 years	95	4 (4.2)	20.6	(20.0, 21.2)	92	92 (100)	7296	(5939, 8962)	< .001	< .001
	27–45 years	162	13 (8.0)	21.7	(20.6, 22.8)	147	147 (100)	2524	(2183, 2918)	< .001	< .001
HPV18	All participants	526	9 (1.7)	20.3	(20.1, 20.5)	504	503 (99.8)	4223	(3785, 4713)	< .001	< .001
	9–17 years	271	3 (1.1)	20.2	(20.0, 20.3)	263	262 (99.6)	5826	(5087, 6672)	< .001	< .001
	18–26 years	95	1 (1.1)	20.2	(19.9, 20.4)	91	91 (100)	3892	(3103, 4882)	< .001	< .001
	27–45 years	160	5 (3.1)	20.6	(20.1, 21.2)	150	150 (100)	2525	(2016, 3162)	< .001	< .001
Month 12
HPV16	All participants	532	10 (1.9)	20.5	(20.1, 21.0)	504	503 (99.8)	1128	(1030, 1236)	< .001	< .001
	9–17 years	275	2 (0.7)	20.5	(19.7, 21.4)	265	265 (100)	1578	(1408, 1768)	< .001	< .001
	18–26 years	95	1 (1.1)	20.2	(19.9, 20.4)	92	92 (100)	954	(798, 1140)	< .001	< .001
	27–45 years	162	7 (4.3)	20.8	(20.2, 21.4)	147	146 (99.3)	684	(572, 817)	< .001	< .001
HPV18	All participants	526	6 (1.1)	20.5	(19.9, 21.1)	504	489 (97.0)	1835	(1581, 2130)	< .001	< .001
	9–17 years	271	3 (1.1)	20.8	(19.7, 22.0)	263	262 (99.6)	3111	(2687, 3603)	< .001	< .001
	18–26 years	95	0 (0.0)	20.0	(20.0, 20.0)	91	90 (98.9)	1360	(963, 1922)	< .001	< .001
	27–45 years	160	3 (1.9)	20.3	(20.0, 20.6)	150	137 (91.3)	872	(620, 1226)	< .001	< .001

*SCR: seroconversion rate (% of group who seroconverted); ^#p values for differences between respective placebo and vaccine groups.

a. iPPS = Immunogenicity Per Protocol Set.