Figure 2.

Control chart analysis of the effectiveness of the 9vHPV vaccine against HPV16/18/31/33/45/52/58-related CIN2, CIN3, AIS, and cervical cancer in the PPE population. The incidence of HPV-related disease was evaluated at 2-year intervals during the LTFU period and, if plotted incidences crossed the 1.83- and 2.75-sigma control limits of the control chart, an inference was made that the accumulating data were indicative of waning effectiveness. Shaded intervals indicate intervals with insufficient follow-up time to declare statistical significance. The center line indicates the expected count in each interval. 9vHPV, nine-valent human papillomavirus; AIS, adenocarcinoma in situ; CIN, cervical intraepithelial neoplasia; HPV, human papillomavirus; LTFU, long-term follow-up; PPE, per-protocol effectiveness