Human papillomavirus vaccines: key factors in planning cost-effective vaccination programs

Abstract

Prophylactic HPV vaccines hold tremendous potential for reducing cervical and non-cervical HPV-related disease burden worldwide. To maximize on this potential, policy officials will need to carefully consider available evidence, existing uncertainties and the cost–effectiveness of mass HPV vaccination programs in the context of their respective nations and/or regions. Proper harmonization of primary prevention strategies with secondary prevention efforts will also be important. Decisions following such considerations may ultimately depend on programmatic objectives, infrastructure and available resources. Continued research and surveillance surrounding HPV vaccination will be essential for filling current knowledge gaps, and forcing ongoing reconsiderations of selected immunization strategies.

Keywords:

• cancer
• Cervarix^®
• cervical cancer
• cost–effectiveness
• Gardasil^®
• genital warts
• HPV
• screening
• vaccination

Financial & competing interests disclosure

EL Franco has served as occasional consultant or advisory board member to Merck and GSK on HPV vaccines, to Qiagen, Roche, GenProbe and Becton & Dickinson on HPV diagnostics, to Cytyc and Ikonisys on cytology and to Innovus and Scimetrika on health economic modeling. This work was partially supported by the Canadian Institutes of Health Research Doctoral award to SD Isidean and Team grant CRN-83320 to EL Franco. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• The duration of protective efficacy conferred by available human papillomavirus (HPV) vaccines is still unknown, but is likely to exceed 10 years (at the least).

• HPV vaccination has begun to yield a population-level impact in reducing the incidence of anogenital warts and cervical precancerous lesions.

• Both vaccines have demonstrated cross-protective efficacy against one or more non-vaccine HPV types, though the duration of this efficacy is undetermined.

• Individuals receiving fewer than three doses of HPV vaccine demonstrate non-inferior immune responses to those receiving three doses. The duration of protection offered by adapted vaccine schedules is unknown.

• Reductions in vaccine-targeted HPV types may lead to apparent increases in non-vaccine types caused by ‘unmasking’. Investigators must take this into account when evaluating vaccine effectiveness and potential HPV type replacement.

• Natural type competition (between vaccine-targeted and non-vaccine HPV types) is considered a prerequisite for HPV type replacement to occur. Fortunately, epidemiological studies have not provided any strong evidence of this competition, suggesting that type replacement is unlikely.

• Recent findings indicate that HPV vaccination may also be an important preventive measure for non-cervical, HPV-related cancers in both men and women.

• Vaccination of young girls has been consistently described as cost-effective for the prevention of HPV-related disease. Current assessments may prove to be underestimates as long-term efficacy data against cervical and non-cervical end points are accumulated.

• The success of HPV vaccination will force a change in the cervical cancer screening paradigm during the next 5–10 years. Ultimately, as new and more efficacious vaccines become available, a complete rethinking of secondary prevention will be warranted.