Table 2.

HPV16/18 vaccine efficacy against prevalent cervical, anal, and oral HPV16/18 DNA four years after vaccination in the “Naïve” cohort*,†

Study population	Arm	Women or sites	No. events	HPV16/18 prevalence, %	Efficacy (95% CI), %
Cervical, anal, or oral HPV16/18	HPV vaccine	970	15	1.5	83.5 (72.1 to 90.8)
Multisite woman level‡	Control	949	89	9.4
Cervical HPV16/18	HPV vaccine	970	8	0.8	89.4 (79.0 to 95.2)
	Control	949	74	7.8
Anal HPV16/18	HPV vaccine	970	7	0.7	85.1 (68.4 to 93.8)
	Control	949	46	4.8
Cervical, anal, oral HPV16/18	HPV vaccine	2910	15	0.5	88.2 (79.6 to 93.1)
Multisite infection level§	Control	2847	124	4.4
HPV16/18 at two or three sites	HPV vaccine	970	0	0.0	100.0 (91.0 to 100.0)
	Control	949	34	3.6

* The naïve cohort excluded those who were human papillomavirus (HPV) 16/18 seropositive at baseline or high-risk cervical HPV DNA+ at baseline or had loop electrosurgical excision procedure during the vaccination phase. CI = confidence interval; HPV = human papillomavirus. † The vaccine efficacy for oral HPV16/18 alone was excluded given low number of events. These results are presented in Supplementary Table 2 (available online).

‡ A woman-level event is defined as a woman who is positive for cervical, anal, and/or oral HPV DNA at the four-year visit.§ An infection-level event is defined as a woman’s anatomical site having HPV16/18 DNA (women contribute three times for each anatomic site); the vaccine efficacies for this analysis utilized generalized estimating equations to adjust for the correlation within an individual.