Figure 3. Sensitivity analysis: Vaccine efficacy. Effect of a change in Human papillomavirus (HPV) vaccine efficacy on the cost effectiveness of vaccination compared with current practice under varying assumptions of vaccine immunity. The triangles represent a vaccine which provides lifetime immunity to high-risk types of HPV. The circles represent a vaccine which requires booster shots every 10 years to remain effective (base-case assumption). The hatches represent a vaccine that requires booster shots every 5 years to remain effective. The dashed line indicates the $50,000 per quality-adjusted life year cost-effectiveness threshold. The base-case value of 75% efficacy is indicated by the arrow.