HPV vaccination strategies

World Health Organization recommendations

…prevention of cervical cancer or other HPV-related diseases, or both, constitutes a public health priority; vaccine introduction is programmatically feasible; sustainable financing can be secured; and the cost effectiveness of vaccination strategies in the country or region is considered. HPV vaccines are most efficacious in females who are naive to vaccine-related HPV types; therefore, the primary target population should be selected based on data on the age of initiation of sexual activity and the feasibility of reaching young adolescent girls through schools, health-care facilities or community-based settings. The primary target population is likely to be girls within the age range of 9 or 10 years through to 13 years.

Programmes introduced to prevent cervical cancer should initially prioritize high coverage in the primary target population of young adolescent girls. Vaccination of secondary target populations of older adolescent females or young women is recommended only if this is feasible, affordable, cost effective, does not divert resources from vaccinating the primary target population or effective cervical cancer screening programmes, and if a significant proportion of the secondary target population is likely to be naive to vaccine-related HPV types.³⁶

Age for vaccination

Many countries have adopted policies that support vaccination of female adolescents before sexual debut (usually around ages 10 to 14). Although vaccination even earlier in life poses no theoretical risk, no studies have yet been published to support vaccination of very young girls or infants. Thus far, it is not recommended that sexually active, older women be vaccinated, since both vaccines show much lower effectiveness after HPV infection. Rather, cervical screening is the best approach for this group.^1,36 Because the incidence of cervical cancer is highest in women more than 40 years of age, screening is especially important in older women (see Continued need for screening below).

Subsidies for vaccines

In low-resource countries, vaccination with current vaccines will be possible only with substantial vaccine subsidies. The GAVI Alliance³⁷ is considering providing HPV vaccine at a reduced cost to the poorest countries in the world.

Strategies for vaccinating girls currently are being explored in PATH-led HPV vaccination demonstration projects in India, Peru, Uganda, and Vietnam.³⁸ The strategies include:

• Vaccinating girls in school settings (with outreach to out-of-school girls).
• Vaccinating as part of a campaign to reach older children with other health interventions (such as Uganda’s semi-annual Child Days Plus program).
• Vaccinating girls in community health clinics.

Lessons learned from these demonstration vaccination programs will help give countries the tools they need to develop effective local programs. Forecasting and delivery strategies (in schools or community programs) can also be guided by this information.

Ensuring access to HPV vaccine

Young adolescents do not routinely interact with health systems in most developing countries, and ensuring access will be a challenge. One promising suggestion is to strengthen school health programs, especially because of the recent increase in primary school attendance in some countries. Where many young girls drop out of school at an early age, community programs might help to fill the gap.

Once effective strategies have been developed to reach these girls, they can be used to provide additional health interventions appropriate for older children, such as other immunizations, deworming, malaria intermittent preventive treatment, provision of bed nets, nutritional supplementation, and general health and life skills education. Using one system to deliver multiple interventions—at the same time as HPV vaccination or at different times—will lower the cost of all the interventions.

Continued need for screening

Although the new HPV vaccines are expected to significantly reduce the risk and incidence of cervical cancer, they will not replace screening; rather, use of the vaccines in partnership with screening will maximize effectiveness.^39,40 Screening is needed for the millions of women aged 30 or older in whom HPV infection has likely occurred if they have been sexually active sometime in their lives. Because the new vaccines are not therapeutic, they cannot benefit women who are already infected. In these women, the effects would be much smaller, probably protecting against the type not yet encountered.

Countries with screening programs already in place should continue to support screening even if a vaccination program is instituted. In countries without screening programs, policymakers should consider initiating screening of women aged 30 and older once or twice in their lifetimes, in conjunction with vaccination of girls and young women who are not yet sexually active.^15,40,41 To learn more, visit the Screening section.

Vaccinating boys

Vaccinating boys is not cost-effective in the developing world.
Boys can become infected with HPV, they can infect female partners, and they can develop HPV-associated diseases such as penile, anal, and oral cancers or genital warts. Some experts believe that vaccinating both males and females would benefit women because women are infected by male sexual partners, but computer models suggest that this strategy may not be cost-effective unless vaccine coverage of girls is low.⁴²

Unanswered questions about HPV vaccines

Current research projects and clinical trials are addressing questions:

• Will booster shots be necessary, and if so, when and how often?
• What is the optimal dosing regimen? Can protection be achieved with fewer than three doses? Can doses be delivered on schedules different from the current ones?
• Are the vaccines safe in pregnant and breastfeeding women?

• Is co-administration with other adolescent vaccines safe and effective?

Future vaccines

Second-generation prophylactic vaccines

• Lower price.
• Longer shelf life.
• Stable at a range of temperatures.
• Effective after only one or two doses.
• Function when given nasally or orally.
• Effective against multiple high-risk HPV types.
• Confer long-lasting immunity without boosters.

Investigators are working on second generation prophylactic vaccines that may address some of these needs.^43,44

Therapeutic vaccines

Photo: PATH (center), PATH/Amynah Janmohamed (right)