HPV HANDBOOK - Zervita

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THE POTENTIAL PUBLIC HEALTH IMPACT OF VACCINES AGAINST HPVVaccine efficacy and effectiveness• Efficacy: measures how well an intervention can work underideal conditions, such as a vaccine trial• Effectiveness: measures the impact of an intervention undermore realistic conditions: for example, in an immunizationprogramme that does not vaccinate 100% of the targetpopulationHPV clinical vaccine trials should provide data on the ‘efficacy’ of thevaccine, but how this factor relates to take, degree and also durationof protection may be unclear. However, the very high seroconversionrate in early clinical trials, together with the high level of protection inanimal models, suggests that there could be a high take against theparticular viral types included in the vaccine.Model definitionTo advance from simple theory, we developed a compartmental,deterministic model and applied it to the question of whether womenand men, or women only, should be vaccinated (see box on page 66).For both squamous intraepithelial lesions (SIL) and CC, at highvaccination coverage, the additional benefit achieved by vaccinatingmen as well as women is small. For men, the HPV vaccine would carrythe risks of immunization but little benefit, although the inclusion oflow-risk HPV types 6 and 11 would potentially decrease the incidenceof genital warts. 11 There may also be immunological reasons whyimmunization should be confined to women: if breakthrough infectionsdo occur among vaccinated women, mucosal antibodies coating theshed virus may neutralize the virus and stop transmission tosusceptible men, thus reducing the need for men to be vaccinated (JSchiller, personal communication). If vaccination of men carries littlebenefit, then resources could be conserved and public strategiesshould concentrate on vaccinating women only.65
3: HPV AND CERVICAL CANCER: PUBLIC HEALTH PERSPECTIVESShould men also be vaccinated?Model integrating HPV-progress-to-disease-with-ageand HPV transmissionModel assumptions• Based on developingcountry demographics• Population growth rate of3% annually• Individuals are eithervaccinated at 15 years ofage or remain susceptibleto HPV infection• Sexual activity begins at 15years of age• Population was stratifiedaccording to age (0–85years) and sexual activityclass (i = 1, 2…4), definedaccording to the rate ofsexual partner changeConclusionsMale vaccination would:• Protect women• Protect homosexual men• Expose heterosexual mento risks associated withvaccination, while only aminority might benefit fromprevention of low-incidenceHPV anogenital and head/neck cancers• Produce small benefits inHSIL and CC reduction• Be most effective at lowvaccine overall coverage(a)BirthsSusceptibleVaccineprotectionVaccine failureRegressionVaccinated(b)BirthsSusceptible0.9Vaccine protection• Coverage• Age at vaccination• TakeVaccine failure• Degree• Duration0.5VaccinatedDeaths from CCHPVLSILHSILCCInfectedPersistence0.1CancersurvivorsFigure 3 Modelling the natural history of infection in (a) men and (b) women66
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THE HEALTH PROFESSIONAL’SHPV HAND
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ContentsList of contributors 7Intro
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Introduction to the HPV Handbook se
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3: HPV AND CERVICAL CANCER: PUBLIC
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Page 26 and 27: 2. HPV testing as a screeningtest:
Page 28 and 29: HPV TESTING AS A SCREENING TEST: TH
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Page 68 and 69: THE POTENTIAL PUBLIC HEALTH IMPACT
Page 80 and 81: Indexadenocarcinoma,detection by HP
Page 82 and 83: INDEXuse in ASCUS 53use to confirm
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HPV HANDBOOK - Zervita

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