Chapter 21: Modelling the impact of HPV vaccines on cervical cancer and screening programmes

A guide to global access to HPV vaccination to all women in low- and middle-income countries; a minireview of innovation and equity

Introduction

Cervical cancer is caused by the human papillomavirus (HV), and accounts for more than 311,000 preventable deaths annually, with 85% occurring in low-and middle-income countries. Despite being preventable through screening and screening, significant barriers to implementing HPV vaccination persist in developing nations. This review study aims to identify these barriers and propose innovative, evidence-based solutions to improve vaccination rates and reduce cervical cancer mortality.

Methods

A systematic review search was conducted using PubMed, Embase, and Cochrane Database of Systemic Reviews. Keywords related to HPV vaccination barriers and implementation strategies in developing countries were used. Relevant demonstration projects, pilot studies, and evidence-based research articles were reviewed.

Results

Identifiable barriers to a successful vaccine implementation program in a developing country include vaccine costs, societal, cultural resistance, misinformation, logistical challenges in vaccine delivery, and inadequate human resources. Solutions to these barriers include a subsidized vaccine pricing, community sensitization, education and well-trained media professionals to dispel misinformation, and partnerships with both public and private sector for efficient vaccine distribution.

Discussion

These findings highlight critical barriers that impede HPV vaccination efforts in developing countries and offers practical solutions to overcome these challenges. This aggregate of data can help inform future developing countries' implementation programs to further the World Health Assembly mission to vaccinate 90% of eligible girls globally by 2030.

Using branded behaviour change communication to create demand for the HPV vaccine among girls in Malawi: An evaluation of Girl Effect's Zathu mini magazine

The HPV vaccine was introduced nationally in Malawi in 2019 and administered to 9-year-old girls. In order to drive uptake of the HPV vaccine Girl Effect utilised their youth brand, Zathu, to deliver messaging on the HPV vaccine. A Zathu 'mini magazine' was created specifically for 9-year-old girls to provide information, prompt household conversations and build empowerment around the HPV vaccine. This evaluation assessed the effectiveness of the Zathu mini magazine against two outcomes: (1) Girls are more informed & motivated to receive the HPV vaccine and (2) Girls talk to their caregivers about the HPV vaccine.A quasi-experimental approach was adopted using both qualitative and quantitative data collection to measure the results against these outcomes. The study found positive correlations between consumption of the Zathu mini magazine and awareness of cervical cancer, and positive attitudes towards the HPV vaccine among girls and parents in the exposed group compared to the non-exposed group. The Zathu mini magazine also encouraged household discussions on the HPV vaccine. Most significantly, consumption of the mini magazine was also positively correlated with uptake of the HPV vaccine among girls. This study highlights the value of girl-centred communications in demand generation for the HPV vaccine. There is potential to learn from and replicate this approach in other comparable settings.

Analytical performance of a low-cost multiplex polymerase chain reaction human papillomavirus genotyping assay for use in Sub-Saharan Africa

We have tested a multiplex polymerase chain reaction (PCR) human papillomavirus (HPV) genotyping assay to fill the need for rapid and low-cost HPV detection in Sub-Saharan Africa. This method allows high throughput genotyping and simultaneous detection of 14 high-risk and two low-risk HPV types, by PCR amplification of HPV DNAs in a single reaction tube. In this study, we describe stepwise experiments to validate the multiplex HPV PCR assay for determination of HPV genotypes from 104 cervical brush samples from Tanzanian women. Assay performance was evaluated by determination of intra-laboratory reproducibility, sensitivity, and specificity. Further performance was assessed by comparison with the widely accepted and validated HPV My09/My11 amplification and hybridization assay. Statistics; the Cohen kappa (κ) and McNemar P values were used to analyze interobserver and intermethod agreement. Overall concordance between the multiplex and line blot hybridization assays was 99% (per sample) with a κ value equal to 0.95; and 96.49% (per detection event) with a κ value of 0.92. Interobserver reproducibility of the assay per sample was 95.76% with κ of 0.91. These results demonstrate that the multiplex HPV PCR assay has high analytical sensitivity and specificity in detecting as many as 16 different HPV genotypes and that its simplicity and low cost makes it well suited for sub-Saharan Africa.

Nonidentifiability in Model Calibration and Implications for Medical Decision Making

BACKGROUND

Calibration is the process of estimating parameters of a mathematical model by matching model outputs to calibration targets. In the presence of nonidentifiability, multiple parameter sets solve the calibration problem, which may have important implications for decision making. We evaluate the implications of nonidentifiability on the optimal strategy and provide methods to check for nonidentifiability.

METHODS

We illustrate nonidentifiability by calibrating a 3-state Markov model of cancer relative survival (RS). We performed 2 different calibration exercises: 1) only including RS as a calibration target and 2) adding the ratio between the 2 nondeath states over time as an additional target. We used the Nelder-Mead (NM) algorithm to identify parameter sets that best matched the calibration targets. We used collinearity and likelihood profile analyses to check for nonidentifiability. We then estimated the benefit of a hypothetical treatment in terms of life expectancy gains using different, but equally good-fitting, parameter sets. We also applied collinearity analysis to a realistic model of the natural history of colorectal cancer.

RESULTS

When only RS is used as the calibration target, 2 different parameter sets yield similar maximum likelihood values. The high collinearity index and the bimodal likelihood profile on both parameters demonstrated the presence of nonidentifiability. These different, equally good-fitting parameter sets produce different estimates of the treatment effectiveness (0.67 v. 0.31 years), which could influence the optimal decision. By incorporating the additional target, the model becomes identifiable with a collinearity index of 3.5 and a unimodal likelihood profile.

CONCLUSIONS

In the presence of nonidentifiability, equally likely parameter estimates might yield different conclusions. Checking for the existence of nonidentifiability and its implications should be incorporated into standard model calibration procedures.

Modeling of US Human Papillomavirus (HPV) Seroprevalence by Age and Sexual Behavior Indicates an Increasing Trend of HPV Infection Following the Sexual Revolution

Background

The United States has experienced an increase in the incidence of human papillomavirus (HPV)-related cancers that are not screen-detectable. It has been hypothesized, but not directly demonstrated, that this is due to increasing HPV prevalence in the unvaccinated population.

Methods

Female self-reported numbers of lifetime sex partners and HPV serology from the National Health and Nutrition Examination Survey (NHANES) were used to develop mathematical models of sexual partner acquisition and antibody dynamics. Modeled trends in sexual behaviors were compared to incidence data for cervical adenocarcinoma, oropharyngeal cancer, and anal cancer.

Results

The age-specific HPV seroprevalence data were best explained by a partner acquisition model that explicitly accounted for cohort-dependent changes in sexual behavior. Estimates of the mean time to loss of natural antibodies varied by model, ranging from 49 to 145 years. Inferred trends in sexual behavior over the past decades paralleled the increasing incidence of HPV-related cancers in the United States.

Conclusions

The findings suggest that lower HPV seroprevalence in older US women primarily reflects cohort-specific differences in sexual behaviors, and is only marginally attributable to immune waning with age. Our results emphasize the importance of continuing surveillance of sexual behaviors, alongside vaccine status, to predict future disease burden.

Extending the Human Papillomavirus Vaccination Programme to Include Males in High-Income Countries: A Systematic Review of the Cost-Effectiveness Studies

BACKGROUND AND OBJECTIVES

Giving the human papillomavirus (HPV) vaccination to females has been shown to be cost-effective in most countries. The epidemiological evidence and economic burden of HPV-related diseases have gradually been shown to be gender neutral. Randomized clinical trials report high efficacy, immunogenicity and safety of the HPV vaccine in males aged 16-26 years. Some pioneering countries extended their HPV vaccination programme to include males, regardless of the cost-effectiveness analysis results. Nevertheless, decision makers need evidence provided by modelling and economic studies to justify the funding of mass vaccination. This systematic review aims to assess the cost-effectiveness of extending the HPV vaccination programme to include males living in high-income countries.

METHODS

A systematic review of the cost-effectiveness analyses of HPV vaccination in males was performed. Data were extracted and analysed using a checklist adapted from the Consolidated Health Economic Evaluation Reporting Standards Statement.

RESULTS

Seventeen studies and 12 underlying mathematical models were identified. Model filiation showed evolution in time from aggregate models (static and dynamic) to individual-based models. When considering the health outcomes HPV vaccines are licensed for, regardless of modelling approaches and assumptions, extending vaccinations to males is rarely found to be cost-effective in heterosexual populations. Cost-effectiveness ratios become more attractive when all HPV-related diseases are considered and when vaccine coverage in females is below 40%.

CONCLUSION

Targeted vaccination of men who have sex with men (MSM) seems to be the best cost-effectiveness option. The feasibility of this strategy is still an open question, since early identification of this specific population remains difficult.

Determinants in the Uptake of the Human Papillomavirus Vaccine: A Systematic Review Based on European Studies

Background

Cervical cancer is the fourth most common cancer affecting women worldwide. Since 2006, two human papillomavirus vaccines (HPVV) have been licensed to protect women against the virus that causes cervical cancer. However, worldwide coverage remains unequal. Studies from the USA found strong evidence for differences in HPVV uptake by ethnicity and healthcare coverage. As the profile of ethnic groups and the healthcare system in the USA differ from countries in Europe where HPVV is free in most of the countries, we conducted a systematic review in order to analyze the determinants of HPVV uptake in Europe.

Methods

We performed a systematic Pubmed, Scopus, and Science Direct search to find articles published from HPVV availability in European countries until April 2014. No age restriction was applied. We included all studies assessing factors associated with HPVV uptake. Uptake refers to either initiation and/or completion of the three dose vaccination program.

Results

Out of the 23 eligible studies, 14 were retrospective reviews of data, six were cross-sectional surveys, and three were prospective cohort studies. Higher HPVV uptake was associated with ethnic majority populations, higher socio-economic status, regular cervical screening participation by the mother, and having received previous childhood vaccinations.

Conclusion

Since the vaccine is offered for free in most of the European countries, the findings suggest that ethno-cultural and educational factors play an important role when it comes to HPVV uptake. Girls who were undervaccinated had also a lower uptake of standard childhood vaccines and mothers who were less likely to attend cervical cancer screening. This may indicate that only few parents have specific concerns with HPVV, and that preventive health care should seek ways to target these vulnerable groups.

Systematic review of model-based cervical screening evaluations

BACKGROUND

Optimising population-based cervical screening policies is becoming more complex due to the expanding range of screening technologies available and the interplay with vaccine-induced changes in epidemiology. Mathematical models are increasingly being applied to assess the impact of cervical cancer screening strategies.

METHODS

We systematically reviewed MEDLINE®, Embase, Web of Science®, EconLit, Health Economic Evaluation Database, and The Cochrane Library databases in order to identify the mathematical models of human papillomavirus (HPV) infection and cervical cancer progression used to assess the effectiveness and/or cost-effectiveness of cervical cancer screening strategies. Key model features and conclusions relevant to decision-making were extracted.

RESULTS

We found 153 articles meeting our eligibility criteria published up to May 2013. Most studies (72/153) evaluated the introduction of a new screening technology, with particular focus on the comparison of HPV DNA testing and cytology (n = 58). Twenty-eight in forty of these analyses supported HPV DNA primary screening implementation. A few studies analysed more recent technologies - rapid HPV DNA testing (n = 3), HPV DNA self-sampling (n = 4), and genotyping (n = 1) - and were also supportive of their introduction. However, no study was found on emerging molecular markers and their potential utility in future screening programmes. Most evaluations (113/153) were based on models simulating aggregate groups of women at risk of cervical cancer over time without accounting for HPV infection transmission. Calibration to country-specific outcome data is becoming more common, but has not yet become standard practice.

CONCLUSIONS

Models of cervical screening are increasingly used, and allow extrapolation of trial data to project the population-level health and economic impact of different screening policy. However, post-vaccination analyses have rarely incorporated transmission dynamics. Model calibration to country-specific data is increasingly common in recent studies.

Knowledge about human papillomavirus and the human papillomavirus vaccine in Belgian students

Introduction

The aim of this study was to examine the knowledge of Belgian university students about the human papillomavirus (HPV) and HPV–vaccination.

Material and methods

During a period of two months we administered an online questionnaire, which contained 29 questions, to 3332 students of the Free University of Brussels. Of the 433 completed questionnaires, 346 were included by age (18–30 years) and completeness of responded questionnaires. These formed the study group.

Results

Of the 346 included questionnaires (76% female), 48% were completed by medical students. The majority (65%) knew that both genders could be infected with HPV. Ninety–five percent of all medical students were aware of the existence of HPV, while 92% knew of the possibility to be vaccinated against the virus. Ninety percent of them were aware of the causal relationship between HPV infection and cervical cancer. 46% of the medical students were aware that HPV can cause anogenital cancers, and only 28% knew that HPV–vaccination could protect them against genital warts. Sixty percent of all female students were fully vaccinated against HPV, without any difference between medical and non–medical students. A very small part of all students (3%) believed that vaccination against HPV could enhance a promiscuous lifestyle.

Conclusions

Almost 80% of respondents were aware of the existence of the human papillomavirus, its morbid potential and the HPV–vaccination.

HPV vaccine acceptability in Africa: a systematic review

OBJECTIVE

The objective of this study was to provide a systematic review of peer-reviewed literature on the factors associated with HPV vaccine acceptability among adults in African countries.

METHODS

A systematic search was conducted across five electronic databases: EMBASE, PsychINFO, CINAHL, Global Health and Ovid MEDLINE, to identify studies related to HPV vaccination acceptability in African countries (August 2013). The Health Belief Model was used to guide data abstraction and synthesis.

RESULTS

Fourteen unique studies representing ten sub-Saharan African countries were identified, with more than half published within the last two years. Acceptability of the HPV vaccine for daughters was high (range 59-100%); however, vaccine-related awareness and knowledge were low. Perceived barriers including accessibility and cost concerns were important for acceptance, as were cues to action from healthcare providers and governments.

CONCLUSIONS

This review suggests that acceptability of the HPV vaccine in countries in this region will be high. Broad knowledge gaps were highlighted regarding HPV and cervical cancer and these should be addressed. Education on the vaccine's effectiveness and reducing perceived barriers to vaccination would also be useful. Public endorsement by governments and healthcare providers will likely also increase acceptance.

Incremental benefits of male HPV vaccination: accounting for inequality in population uptake

BACKGROUND

Vaccines against HPV16/18 are approved for use in females and males but most countries currently have female-only programs. Cultural and geographic factors associated with HPV vaccine uptake might also influence sexual partner choice; this might impact post-vaccination outcomes. Our aims were to examine the population-level impact of adding males to HPV vaccination programs if factors influencing vaccine uptake also influence partner choice, and additionally to quantify how this changes the post-vaccination distribution of disease between subgroups, using incident infections as the outcome measure.

METHODS

A dynamic model simulated vaccination of pre-adolescents in two scenarios: 1) vaccine uptake was correlated with factors which also affect sexual partner choice ("correlated"); 2) vaccine uptake was unrelated to these factors ("unrelated"). Coverage and degree of heterogeneity in uptake were informed by observed data from Australia and the USA. Population impact was examined via the effect on incident HPV16 infections. The rate ratio for post-vaccination incident HPV16 in the lowest compared to the highest coverage subgroup (RR(L)) was calculated to quantify between-group differences in outcomes.

RESULTS

The population-level incremental impact of adding males was lower if vaccine uptake was "correlated", however the difference in population-level impact was extremely small (<1%) in the Australia and USA scenarios, even under the conservative and extreme assumption that subgroups according to coverage did not mix at all sexually. At the subgroup level, "correlated" female-only vaccination resulted in RR(L)= 1.9 (Australia) and 1.5 (USA) in females, and RR(L)= 1.5 and 1.3 in males. "Correlated" both-sex vaccination increased RR(L) to 4.2 and 2.1 in females and 3.9 and 2.0 in males in the Australia and USA scenarios respectively.

CONCLUSIONS

The population-level incremental impact of male vaccination is unlikely to be substantially impacted by feasible levels of heterogeneity in uptake. However, these findings emphasize the continuing importance of prioritizing high coverage across all groups in HPV vaccination programs in terms of achieving equality of outcomes.

Evaluation of soluble CD44 protein marker to distinguish the premalignant and malignant carcinoma cases in cervical cancer patients

The main objective of the present study was to estimate the levels of soluble CD44 in cervical cancer patients by determining whether it consistently discriminates the carcinoma of the cervix from early or premalignant stage of the cervical cancer. Serum concentrations of sCD44s in cervical cancer patients were determined by an enzyme-linked immunosorbent assay from serum of 50 cases of cervical cancer patients and 50 cases of suspected patients with premalignant disease of cervical intraepithelial neoplasia. The sensitivity and specificity of the test for differentiating carcinoma of the cervix from premalignant stage were evaluated by plotting receiver operating characteristic (ROC) curve. Significant increase in the levels of soluble CD44 was observed in cervical cancer patients (664.80 ± 26.58 ng/ml), when compared to healthy (P < 0.001) and suspected (P < 0.05) or premalignant cases (275.19 ± 24.39 and 514.33 ± 54.57 ng/ml, respectively). High-grade squamous intraepithelial lesions, adenocarcinoma in situ and premalignance with dysplasia show significant (P < 0.001) increase in the concentration of soluble CD44 levels when compared to other types. A ROC curve was plotted and estimated the threshold value as 633.11 ng/ml. In conclusion, the data indicated an up-regulation of soluble CD44 protein which detect and differentiates the cervical carcinoma from premalignant cases with 62.6 % sensitivity.

The potential impact of HPV-16 reactivation on prevalence in older Australians

BACKGROUND

Some regional cross-sectional human papillomavirus (HPV) DNA prevalence data show an increase in prevalence in older women, the reasons for which are as yet unknown. A recently published study suggests that the increase may be at least partly due to reactivation of latent HPV in menopausal women.

METHODS

We developed a dynamic mathematical model of HPV-16 transmission to estimate the key consequences of hypothetical HPV-16 reactivation in the Australian heterosexual population. We only consider a worst case scenario with regard to reactivation in the Australian setting when all women who are latently infected reactivate and, wherever feasible, we choose model parameter values which may lead to a more pronounced reactivation. The ongoing National HPV vaccination program covering both women and men is incorporated in the model.

RESULTS

We estimate that about 1 in 10 women and men who appear to have cleared HPV-16 infection may be latently infected. The prevalence of HPV-16 in older Australian women will increase by a factor of up to 3.1 between now and 2025 which will be accompanied by an increase by a factor of around 1.9 in older men. However, the long-term impact of the HPV vaccination is not significantly altered by reactivation.

CONCLUSIONS

If the reactivation hypothesis we consider is substantiated, the public health response should be focused on further improvement of cervical screening coverage for older women. Our study also highlights the urgent need for surveillance of HPV prevalence in older Australians.

Evaluation of serogroup C and ACWY meningococcal vaccine programs: projected impact on disease burden according to a stochastic two-strain dynamic model

OBJECTIVE

Advisory committees in Canada and the United States have updated recommendations for quadrivalent meningococcal conjugate vaccines against serogroups A, C, W135, and Y. Our objective was to evaluate optimally effective meningococcal vaccination policies using a stochastic dynamic model. Canada was used as an example.

METHODS

Our stochastic dynamic model of Neisseria meningitidis (Nm) transmission in an age-structured population assumed partial cross-immunity among two aggregated serogroup categories: 'AWY' containing A, W135, and Y; and 'Other' containing B, C, and ungroupable types. We compared the impact of monovalent C versus quadrivalent ACWY vaccination on Nm carriage and invasive meningococcal disease (IMD). Our model was parameterized with Canadian epidemiological and demographic data and employed probabilistic sensitivity analysis.

RESULTS

Routine infant immunization at 12 months and boosting at 15 years with a quadrivalent vaccine is projected to have the largest impact on total IMD incidence: a 74% reduction over 40 years. Routine infant immunization with a monovalent vaccine at 12 months only has much less impact and also generates strain replacement appearing after approximately ten years of continuous use.

CONCLUSIONS

Immunizing infants at 12 months and boosting adolescents at 15 years with an ACWY vaccine is predicted to be most effective at reducing IMD incidence.

Primary prophylactic human papillomavirus vaccination programs: future perspective on global impact

Of the 40 types of human papillomavirus that can infect the mucosal epithelium, four types can now be prevented using prophylactic vaccination. Two of these types (high-risk types 16 and 18) cause 70% of cervical cancers, a proportion of other genital cancers and a subset of head and neck cancers. The low-risk types 6 and 11 cause 90% of genital warts and the disease recurrent respiratory papillomatosis. Thus, if primary HPV vaccination programs can be implemented effectively, the potential for a reduction in global disease burden is great. This article considers the current issues and challenges in delivering primary HPV vaccination programs effectively and the likely impact of the vaccines in both the near and more distant future.

Estimates of the timing of reductions in genital warts and high grade cervical intraepithelial neoplasia after onset of human papillomavirus (HPV) vaccination in the United States

BACKGROUND

The objective of this study was to estimate the number of years after onset of a quadrivalent HPV vaccination program before notable reductions in genital warts and cervical intraepithelial neoplasia (CIN) will occur in teenagers and young adults in the United States.

METHODS

We applied a previously published model of HPV vaccination in the United States and focused on the timing of reductions in genital warts among both sexes and reductions in CIN 2/3 among females. Using different coverage scenarios, the lowest being consistent with current 3-dose coverage in the United States, we estimated the number of years before reductions of 10%, 25%, and 50% would be observed after onset of an HPV vaccination program for ages 12-26 years.

RESULTS

The model suggested female-only HPV vaccination in the intermediate coverage scenario will result in a 10% reduction in genital warts within 2-4 years for females aged 15-19 years and a 10% reduction in CIN 2/3 among females aged 20-29 years within 7-11 years. Coverage had a major impact on when reductions would be observed. For example, in the higher coverage scenario a 25% reduction in CIN2/3 would be observed with 8 years compared with 15 years in the lower coverage scenario.

CONCLUSIONS

Our model provides estimates of the potential timing and magnitude of the impact of HPV vaccination on genital warts and CIN 2/3 at the population level in the United States. Notable, population-level impacts of HPV vaccination on genital warts and CIN 2/3 can occur within a few years after onset of vaccination, particularly among younger age groups. Our results are generally consistent with early reports of declines in genital warts among youth.

Health care professional communication about STI vaccines with adolescents and parents

Vaccination of adolescents against sexually transmitted infections (STIs) is an important prevention strategy that may reduce the global burden of disease. The World Health Organization, Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices, and other national health agencies recommend the use of existing STI vaccines, and many countries have incorporated them into their routine vaccination schedule. Despite this, however, data indicate that STI vaccine uptake is suboptimal for a variety of reasons. Health care professionals (HCP) have been shown to have a strong beneficial effect on STI vaccine uptake, yet studies demonstrate that many HCPs fail to discuss or recommend them to adolescent patients. This review article focuses on HCP communication about STI vaccines with adolescents and their parents. It describes STI vaccine message content and delivery as well as the context in which HCPs formulate their messaging approach. It also examines other contextual factors that may shape communication about STI vaccines. Studies from many countries indicate that HCPs often possess misinformation about adolescents, including their sexual risk behaviors, as well as STIs, vaccine safety and efficacy, and STI vaccination recommendations. They also have misconceptions of parental barriers to STI vaccination. These may impact STI vaccine communication and have a negative influence on STI vaccine uptake. These findings highlight the critical need for improved HCP education related to adolescent health, sexuality, and STI vaccination. This may be particularly important in settings without an existing infrastructure or expertise in caring for this unique patient population.

Rome Consensus Conference - statement; human papilloma virus diseases in males

BACKGROUND

Human Papillomavirus (HPV) is a very resistant, ubiquitous virus that can survive in the environment without a host. The decision to analyse HPV-related diseases in males was due to the broad dissemination of the virus, and, above all, by the need to stress the importance of primary and secondary prevention measures (currently available for women exclusively). The objective of the Consensus Conference was to make evidence-based recommendations that were designed to facilitate the adoption of a standard approach in clinical practice in Italy.

METHODS

The Sponsoring Panel put a series of questions to the members of the Scientific Committee who prepared a summary of the currently available information, relevant for each question, after the review and grading of the existing scientific literature. The summaries were presented to a Jury, also called multidisciplinary Consensus Panel, who drafted a series of recommendations.

RESULTS

The prevalence of HPV in males ranges between 1.3-72.9%;. The prevalence curve in males is much higher than that in females and does not tend to decline with age. Women appear to have a higher probability of acquiring HPV genotypes associated with a high oncogenic risk, whereas in males the probability of acquiring low- or high-risk genotypes is similar. The HPV-related diseases that affect males are anogenital warts and cancers of the penis, anus and oropharynx. The quadrivalent vaccine against HPV has proved to be effective in preventing external genital lesions in males aged 16-26 years in 90.4%; (95%; CI: 69.2-98.1) of cases. It has also proved to be effective in preventing precancerous anal lesions in 77.5%; (95%; CI: 39.6-93.3) of cases in a per-protocol analysis and in 91.7%; (95%; CI: 44.6-99.8) of cases in a post-hoc analysis. Early ecological studies demonstrate reduction of genital warts in vaccinated females and some herd immunity in males when vaccine coverage is high, although males who have sex with males gained no benefit at all. Males with an immunodeficiency disease are at greater risk of developing disease. Infertility seems to be caused by HPV in some cases. Studies demonstrate vaccination to both genders can be more efficacious and social equity matters are to be taken into consideration.

CONCLUSIONS

The Jury made Recommendations based on the scientific evidence presented by the Scientific Committee. Accordingly, for prevention purposes and social fairness and equality, as both sexes are affected by the disease, the vaccination of 12-year-old males against HPV should be recommended in order to guaranty protection to everyone. Aspects related to healthcare policy and economic sustainability, are to be discussed by respective public system representatives. More campaigns to raise awareness through all institutional channels are needed, not only regarding anogenital warts, but for HPV-related diseases in general in males in accordance to new scientific evidences.

Emerging human papillomavirus vaccines

INTRODUCTION

Identification of human papillomavirus (HPV) as the etiologic factor of cervical, anogenital, and a subset of head and neck cancers has stimulated the development of preventive and therapeutic HPV vaccines to control HPV-associated malignancies. Excitement has been generated by the commercialization of two preventive L1-based vaccines, which use HPV virus-like particles (VLPs) to generate capsid-specific neutralizing antibodies. However, factors such as high cost and requirement for cold chain have prevented widespread implementation where they are needed most.

AREAS COVERED

Next generation preventive HPV vaccine candidates have focused on cost-effective stable alternatives and generating broader protection via targeting multivalent L1 VLPs, L2 capsid protein, and chimeric L1/L2 VLPs. Therapeutic HPV vaccine candidates have focused on enhancing T cell-mediated killing of HPV-transformed tumor cells, which constitutively express HPV-encoded proteins, E6 and E7. Several therapeutic HPV vaccines are in clinical trials.

EXPERT OPINION

Although progress is being made, cost remains an issue inhibiting the use of preventive HPV vaccines in countries that carry the majority of the cervical cancer burden. In addition, progression of therapeutic HPV vaccines through clinical trials may require combination strategies employing different therapeutic modalities. As research in the development of HPV vaccines continues, we may generate effective strategies to control HPV-associated malignancies.

Modeling preventative strategies against human papillomavirus-related disease in developed countries

Over the last 5 years, prophylactic vaccination against human papillomavirus (HPV) in pre-adolescent females has been introduced in most developed countries, supported by modeled evaluations that have almost universally found vaccination of pre-adolescent females to be cost-effective. Studies to date suggest that vaccination of pre-adolescent males may also be cost-effective at a cost per vaccinated individual of ~US$400-500 if vaccination coverage in females cannot be increased above ~50%; but if it is possible, increasing coverage in females appears to be a better return on investment. Comparative evaluation of the quadrivalent (HPV16,18,6,11) and bivalent (HPV16,18) vaccines centers around the potential trade-off between protection against anogenital warts and vaccine-specific levels of cross-protection against infections not targeted by the vaccines. Future evaluations will also need to consider the cost-effectiveness of a next generation nonavalent vaccine designed to protect against ~90% of cervical cancers. The timing of the effect of vaccination on cervical screening programs will be country-specific and will depend on vaccination catch-up age range and coverage and the age at which screening starts. Initial evaluations suggest that if screening remains unchanged, it will be less cost-effective in vaccinated compared to unvaccinated women but, in the context of current vaccines, will remain an important prevention method. Comprehensive evaluation of new approaches to screening will need to consider the population-level effects of vaccination over time. New screening strategies of particular interest include delaying the start age of screening, increasing the screening interval and switching to primary HPV screening. Future evaluations of screening will also need to focus on the effects of disparities in screening and vaccination uptake, the potential effects of vaccination on screening participation, and the effects of imperfect compliance with screening recommendations. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

Risk factors for and prevention of human papillomaviruses (HPV), genital warts and cervical cancer

Genital HPV infection is associated with development of cervical cancer, cervical neoplasia, anogenital warts, and other anogenital cancers. A number of reviews have primarily addressed the role of HPV infection in cervical carcinogenesis, and differences in human papillomavirus (HPV) subtypes found in cervical cancer cases by histology and geographical region. This review provides an informative summary of the broad body of literature on the burden of HPV, the risk factors for HPV infection, genital warts and cervical cancer, and preventive measures against these conditions in females. Studies have identified the main risk factors for genital HPV infection in females as follows: acquisition of new male partners; an increasing number of lifetime sexual partners both in females and their male partners; and having non-monogamous male partners. Cervical cancer screening and HPV vaccination are the primary measures currently recommended to prevent cervical cancer. There is also an ongoing debate and conflicting findings on whether male circumcision and condom use protect against HPV infection and subsequent development of HPV-related illnesses in females.

Frequency and risk factors for prevalent, incident, and persistent genital carcinogenic human papillomavirus infection in sexually active women: community based cohort study

OBJECTIVE

To investigate frequency and risk factors for prevalent, incident, and persistent carcinogenic human papillomavirus (HPV) in young women before the introduction of immunisation against HPV types 16 and 18 for schoolgirls.

DESIGN

Cohort study

SETTING

20 London universities and further education colleges.

PARTICIPANTS

2185 sexually active female students, mean age 21 years (range 16-27), 38% from ethnic minorities, who took part in the POPI (prevention of pelvic infection) chlamydia screening trial in 2004-08 and who provided duplicate, self taken vaginal swabs and completed questionnaires at baseline. At follow-up, a median of 16 months later, 821 women (38%) returned repeat vaginal swabs by post. In 2009-10, stored samples were tested for HPV.

RESULTS

Samples from 404/2185 (18.5% (95% CI 16.9% to 20.2%)) of the cohort were positive for carcinogenic HPV at baseline, including 15.0% (327) positive for non-vaccine carcinogenic genotypes. Reporting two or more sexual partners in the previous year and concurrent Chlamydia trachomatis or bacterial vaginosis were independent risk factors for prevalent vaginal HPV infection. Infection with one or more new HPV types was found in 17.7% (145/821) of follow-up samples, giving an estimated annual incidence of carcinogenic HPV infection of 12.9% (95% CI 11.0% to 15.0%). Incident infection was more common in women reporting two or more partners in the previous year, aged<20, of black ethnicity, or with C trachomatis vaginosis at baseline. Multiple partners was the only independent risk factor for incident infection (adjusted relative risk 1.99 (95% CI 1.46 to 2.72)). Of 143 women with baseline carcinogenic HPV infection, 20 (14% (8.3% to 19.7%) had infection with the same carcinogenic HPV type(s) detected after 12-28 months. Of these women, 13 (65%) had redetected infection with HPV 16 or 18, and nine (45%) with non-vaccine carcinogenic HPV genotypes.

CONCLUSION

In the first UK cohort study of carcinogenic HPV in young women in the community, multiple sexual partners was an independent predictor of both prevalent and incident infection. Infection with non-vaccine carcinogenic genotypes was common. Although current HPV vaccines offer partial cross protection against some non-vaccine carcinogenic HPV types, immunised women will still need cervical screening.

Human papillomavirus vaccination in the resourced and resource-constrained world

Human papillomavirus has been established as the causal agent for cervical cancer. The identification of a clear cause presents an unparalleled opportunity for cancer control. As such, the development of prophylactic human papillomavirus vaccines has been rightly hailed as one of the significant scientific triumphs of the past 20 years. This story of scientific triumph over disease, however, is not yet complete. The fruit of scientific labour must be delivered to the people in order to fulfil the underlying intent of the research (i.e. to prevent cancer and save lives). The success of a vaccination programme, however, does not depend on the biological efficacy of the vaccine alone. Various other local factors, such as poverty, gender inequality, cultural traditions, or religious beliefs, can significantly constrain the success of any vaccination programme. In this chapter, we provide an overview of how the human papillomavirus vaccine works and its global uptake, as well as, how variations in local contexts can affect the successful implementation of a vaccination programme. Other factors besides vaccine costs also need serious attention. With better understanding of such factors, policy makers and medical health professionals will be better equipped to make informed decisions to maximise the potential benefits of the human papillomavirus vaccines for the most number of people in individual countries.

An analytic framework to develop policies for testing, prevention, and treatment of two-stage contagious diseases

In this paper we consider healthcare policy issues for trading off resources in testing, prevention, and cure of two-stage contagious diseases. An individual that has contracted the two-stage contagious disease will initially show no symptoms of the disease but is capable of spreading it. If the initial stages are not detected which could lead to complications eventually, then symptoms start appearing in the latter stage when it would be necessary to perform expensive treatment. Under a constrained budget situation, policymakers are faced with the decision of how to allocate budget for prevention (via vaccinations), subsidizing treatment, and examination to detect the presence of initial stages of the contagious disease. These decisions need to be performed in each period of a given time horizon. To aid this decision-making exercise, we formulate a stochastic dynamic optimal control problem with feedback which can be modeled as a Markov decision process (MDP). However, solving the MDP is computationally intractable due to the large state space as the embedded stochastic network cannot be decomposed. Hence we propose an asymptotically optimal solution based on a fluid model of the dynamics in the stochastic network. We heuristically fine-tune the asymptotically optimal solution for the non-asymptotic case, and test it extensively for several numerical cases. In particular we investigate the effect of budget, length of planning horizon, type of disease, population size, and ratio of costs on the policy for budget allocation.

The Role of Transabdominal Sonography in Facilitating Successful Brachytherapy Outcomes in Cervical Cancer

Radiation is a standard of care in the treatment of locally advanced cervical cancer. Radiation consists of external beam radiation and brachytherapy to optimize local control and cure. High-dose-rate (HDR) brachytherapy is most commonly used in the United States. Advantages of HDR are outpatient treatment, elimination of exposure to medical staff, patient convenience, and the ability to modify the treatment because multiple fractions are used. Accurate placement of the tandem in the uterus is critical to maximize tumor control and minimize complications. Transabdominal sonography offers real-time imaging of the tandem placement, which allows the radiation oncologist to adjust the tandem position, thus ensuring correct dosimetry and treatment. This article discusses the etiology, diagnosis, and treatment of cervical cancer. This article further explains the importance of the brachytherapy technique, the role of transabdominal sonography, and how both can lead to a successful outcome for the patient.

Health economics of screening for gynaecological cancers

In this chapter, we summarise findings from recent cost-effectiveness analyses of screening for cervical cancer and ovarian cancer. We begin with a brief summary of key issues that affect the cost-effectiveness of screening, including disease burden, and availability and type of screening tests. For cervical cancer, we discuss the potential effect of human papilloma virus vaccines on screening. Outstanding epidemiological and cost-effectiveness issues are included. For cervical cancer, this includes incorporating the long-term effect of treatment (including adverse birth outcomes in treated women who are of reproductive age) into cost-effectiveness models using newly available trial data to identify the best strategy for incorporating human papilloma virus tests. A second issue is the need for additional data on human papilloma virus vaccines, such as effectiveness of reduced cancer incidence and mortality, effectiveness in previously exposed women and coverage. Definitive data on these parameters will allow us to update model-based analyses to include more realistic estimates, and also potentially dramatically alter our approach to screening. For ovarian cancer, outstanding issues include confirming within the context of a trial that screening is effective for reducing mortality and incorporating tests with high specificity into screening into screening algorithms for ovarian cancer.

The known unknowns of HPV natural history

The discovery that certain high-risk strains of human papillomavirus (HR-HPV) cause nearly 100% of invasive cervical cancer has spurred a revolution in cervical cancer prevention by promoting the development of viral vaccines. Although the efficacy of these vaccines has already been demonstrated, a complete understanding of viral latency and natural immunity is lacking, and solving these mysteries could help guide policies of cervical cancer screening and vaccine use. Here, we examine the epidemiological and biological understanding of the natural history of HPV infection, with an eye toward using these studies to guide the implementation of cervical cancer prevention strategies.

Sex-specific immunization for sexually transmitted infections such as human papillomavirus: insights from mathematical models

BACKGROUND

Sex-specific differences regarding the transmissibility and the course of infection are the rule rather than the exception in the epidemiology of sexually transmitted infections (STIs). Human papillomavirus (HPV) provides an example: disease outcomes differ between men and women, as does the potential for transmission to the opposite sex. HPV vaccination of preadolescent girls was recently introduced in many countries, and inclusion of boys in the vaccination programs is being discussed. Here, we address the question of whether vaccinating females only, males only, or both sexes is the most effective strategy to reduce the population prevalence of an STI like HPV.

METHODS AND FINDINGS

We use a range of two-sex transmission models with varying detail to identify general criteria for allocating a prophylactic vaccine between both sexes. The most effective reduction in the population prevalence of infection is always achieved by single-sex vaccination; vaccinating the sex with the highest prevaccine prevalence is the preferred strategy in most circumstances. Exceptions arise only when the higher prevaccine prevalence is due to a substantially lower rate of natural immunity, or when natural immunity is lifelong, and a prolonged duration of infectiousness coincides with increased transmissibility. Predictions from simple models were confirmed in simulations based on an elaborate HPV transmission model. Our analysis suggests that relatively inefficient genital transmission from males to females might render male vaccination more effective in reducing overall infection levels. However, most existing HPV vaccination programs have achieved sufficient coverage to continue with female-only vaccination.

CONCLUSIONS

Increasing vaccine uptake among preadolescent girls is more effective in reducing HPV infection than including boys in existing vaccination programs. As a rule, directing prophylactic immunization at the sex with the highest prevaccine prevalence results in the largest reduction of the population prevalence.

The HPV vaccine impact monitoring project (HPV-IMPACT): assessing early evidence of vaccination impact on HPV-associated cervical cancer precursor lesions

The following paper describes a collaboration between the Centers for Disease Control and Prevention and five Emerging Infections Program sites to develop a comprehensive population-based approach to monitoring human papillomavirus (HPV) vaccine impact on cervical cancer precursors and associated HPV genotypes. The process of establishing this novel monitoring system is described, and development details such as enumeration of sources for reporting cervical intraepithelial neoplasia 2/3 and adenocarcinoma in situ, approaches to case ascertainment, electronic reporting, and HPV typing are outlined. Implementation of a feasible and sustainable surveillance system for HPV-associated cervical precancers will enable evaluation of the direct impact of HPV vaccination.

Time for change? An economic evaluation of integrated cervical screening and HPV immunization programs in Canada

Many jurisdictions have implemented universal human papillomavirus (HPV) immunization programs in preadolescent females. However, the cost-effectiveness of modified cervical screening guidelines and/or catch-up immunization in older females in Canada has not been evaluated. We conducted a cost-utility analysis of screening and immunization with the bivalent vaccine for the Canadian setting from the Ministry of Health perspective. We used a dynamic model to capture herd immunity and included cross-protection against strains not included in the vaccine. We found that adding catch-up immunization to the current program would be cost-effective, and that combining catch-up immunization with delaying the age at which screening is first initiated could result in cost savings and net health gains.

Next Generation Cancer Protection: The Bivalent HPV Vaccine for Females

Nearly a half a million women throughout the world develop cervical cancer every year Parkin and Bray ("Chapter 2. The burden of HPVrelated cancers," Vaccine, vol. 24, no. 3, pp. S11-S25, 2006); 80% of these women are in countries without a quality-assured cytology screening program. It is in this setting that Cervarix could reduce the incidence of cervical cancer to about 9.5/100,000 women. New evidence indicates that this might be able to be accomplished with a single dose of Cervarix, a great advantage to public health implementation programs Kreimer et al. ("Proof-of-principle evaluation of the efficacy of fewer than three doses of a bivalent HPV16/18 vaccine, The Journal of the National Cancer Institute, vol. 103, no. 19, pp. 1444-1451, 2011). In countries with screening programs, adenocarcinoma is the most difficult to detect and treat with later-stage presentation and higher mortality Smith et al. ("The rising incidence of adenocarcinoma relative to squamous cell carcinoma of the uterine cervix in the United States-a 24-year population-based study," Gynecologic Oncology, vol. 78, no. 2, pp. 97-105, 2000) and Gunnell et al. ("A longitudinal Swedish study on screening for squamous cell carcinoma and adenocarcinoma: evidence of effectiveness and overtreatment," Cancer Epidemiology Biomarkers and Prevention, vol. 16, no. 12, pp. 2641-2648, 2007). With additional cross-protection to HPV 31, 33, and 45 and protection against HPV 16 and 18 lasting at least 9.4 years, Cervarix may reduce adenocarcinomas in screened populations by more than 90%. This paper will detail the evidence about the efficacy, immunogenicity, and safety of Cervarix in the studied populations contrasting public health goals with individual health options.

Model-based analyses to compare health and economic outcomes of cancer control: inclusion of disparities

BACKGROUND

Disease simulation models of the health and economic consequences of different prevention and treatment strategies can guide policy decisions about cancer control. However, models that also consider health disparities can identify strategies that improve both population health and its equitable distribution.

METHODS

We devised a typology of cancer disparities that considers types of inequalities among black, white, and Hispanic populations across different cancers and characteristics important for near-term policy discussions. We illustrated the typology in the specific example of cervical cancer using an existing disease simulation model calibrated to clinical, epidemiological, and cost data for the United States. We calculated average reduction in cancer incidence overall and for black, white, and Hispanic women under five different prevention strategies (Strategies A1, A2, A3, B, and C) and estimated average costs and life expectancy per woman, and the cost-effectiveness ratio for each strategy.

RESULTS

Strategies that may provide greater aggregate health benefit than existing options may also exacerbate disparities. Combining human papillomavirus vaccination (Strategy A2) with current cervical cancer screening patterns (Strategy A1) resulted in an average reduction of 69% in cancer incidence overall but a 71.6% reduction for white women, 68.3% for black women, and 63.9% for Hispanic women. Other strategies targeting risk-based screening to racial and ethnic minorities reduced disparities among racial subgroups and resulted in more equitable distribution of benefits among subgroups (reduction in cervical cancer incidence, white vs. Hispanic women, 69.7% vs. 70.1%). Strategies that employ targeted risk-based screening and new screening algorithms, with or without vaccination (Strategies B and C), provide excellent value. The most effective strategy (Strategy C) had a cost-effectiveness ratio of $28,200 per year of life saved when compared with the same strategy without vaccination.

CONCLUSIONS

We identify screening strategies for cervical cancer that provide greater aggregate health benefit than existing options, offer excellent cost-effectiveness, and have the biggest positive impact in worst-off groups. The typology proposed here may also be useful in research and policy decisions when trade-offs between fairness and cost-effectiveness are unavoidable.

The cost-effectiveness of male HPV vaccination in the United States

INTRODUCTION

The objective of this study was to estimate the cost-effectiveness of adding human papillomavirus (HPV) vaccination of 12-year-old males to a female-only vaccination program for ages 12-26 years in the United States.

METHODS

We used a simplified model of HPV transmission to estimate the reduction in the health and economic burden of HPV-associated diseases in males and females as a result of HPV vaccination. Estimates of the incidence, cost-per-case, and quality-of-life impact of HPV-associated health outcomes were based on the literature. The HPV-associated outcomes included were: cervical intraepithelial neoplasia (CIN); genital warts; juvenile-onset recurrent respiratory papillomatosis (RRP); and cervical, vaginal, vulvar, anal, oropharyngeal, and penile cancers.

RESULTS

The cost-effectiveness of male vaccination depended on vaccine coverage of females. When including all HPV-associated outcomes in the analysis, the incremental cost per quality-adjusted life year (QALY) gained by adding male vaccination to a female-only vaccination program was $23,600 in the lower female coverage scenario (20% coverage at age 12 years) and $184,300 in the higher female coverage scenario (75% coverage at age 12 years). The cost-effectiveness of male vaccination appeared less favorable when compared to a strategy of increased female vaccination coverage. For example, we found that increasing coverage of 12-year-old girls would be more cost-effective than adding male vaccination even if the increased female vaccination strategy incurred program costs of $350 per additional girl vaccinated.

CONCLUSIONS

HPV vaccination of 12-year-old males might potentially be cost-effective, particularly if female HPV vaccination coverage is low and if all potential health benefits of HPV vaccination are included in the analysis. However, increasing female coverage could be a more efficient strategy than male vaccination for reducing the overall health burden of HPV in the population.

Comparative evaluation of the potential impact of rotavirus versus HPV vaccination in GAVI-eligible countries: a preliminary analysis focused on the relative disease burden

BACKGROUND

Immunization policymakers at global and local levels need to establish priorities among new vaccines competing for limited resources. However, comparison of the potential impact of single vaccination programs is challenging, primarily due to the limited number of vaccine analyses as well as their differing analytic approaches and reporting formats. The purpose of this study is to provide early insight into how the comparative impact of different new vaccines could be assessed in resource-poor settings with respect to affordability, cost-effectiveness, and distributional equity.

METHODS

We compared the health, economic, and financial consequences of introducing the two vaccines in 72 GAVI-eligible countries using a number of different outcome measures to evaluate affordability, cost-effectiveness, and distributional equity. We use simple static models to standardize the analytic framework and improve comparability between the two new vaccines. These simple models were validated by leveraging previously developed, more complex models for rotavirus and human papillomavirus (HPV).

RESULTS

With 70% coverage of a single-age cohort of infants and pre-adolescent girls, the lives saved with rotavirus (~274,000) and HPV vaccines (~286,000) are similar, although the timing of averted mortality differs; rotavirus-attributable deaths occur in close proximity to infection, while HPV-related cancer deaths occur largely after age 30. Deaths averted per 1000 vaccinated are 5.2 (rotavirus) and 12.6 (HPV). Disability-adjusted life years (DALYs) averted were ~7.15 million (rotavirus) and ~1.30 million (HPV), reflecting the greater influence of discounting on the latter, given the lagtime between vaccination and averted cancer. In most countries (68 for rotavirus and 66 for HPV, at the cost of I$25 per vaccinated individual) the incremental cost per DALY averted was lower than each country's GDP per capita. Financial resources required for vaccination with rotavirus are higher than with HPV since both genders are vaccinated.

CONCLUSIONS

While lifesaving benefits of rotavirus and HPV vaccines will be realized at different times, the number of lives saved over each target populations' lifetimes will be similar. Model-based analyses that use a standardized analytic approach and generate comparable outputs can enrich the priority-setting dialogue. Although new vaccines may be deemed cost-effective, other factors including affordability and distributional equity need to be considered in different settings. We caution that for priority setting in an individual country, more rigorous comparisons should be performed, using more comprehensive models and considering all relevant vaccines and delivery strategies.

Modelling the epidemiology of infectious diseases for decision analysis: a primer

The number of economic evaluations related to infectious disease topics has increased over the last 2 decades. However, many such evaluations rely on models that do not take into account unique features of infectious diseases that can affect the estimated value of interventions against them. These include their transmissibility from infected to susceptible individuals, the possibility of acquiring natural immunity following recovery from infection and the uncertainties that arise as a result of their complex natural history and epidemiology. Modellers conducting economic evaluations of infectious disease interventions need to know the main features of different types of infectious disease models, the situations in which they should be applied and the effects of model choices on the cost effectiveness of interventions.

Human papillomavirus vaccines: new tools for accelerating cervical cancer prevention in developing countries

Despite the available knowledge and tools to prevent cervical cancer, it remains the second most common cancer in women, with four-fifths of the cases occurring in developing countries. Projections are for a 90% increase in global cervical cancer cases by 2020 if no additional public-health interventions are implemented. Prophylactic human papillomavirus (HPV) vaccines, which have proven immunogenicity, safety and efficacy, are now commercially available; and coupled together with quality screening have the potential to dramatically accelerate reductions in cervical cancer mortality rates and save millions of women's lives. The current cost of the new HPV vaccines and new screening technologies, however, are a major barrier to their widespread implementation. There is an urgent need for HPV vaccines and new technologies for effective screening to become more available and affordable, especially to poor communities everywhere.

US physicians' intentions regarding impact of human papillomavirus vaccine on cervical cancer screening

BACKGROUND

US cervical cancer screening recommendations have not changed since the human papillomavirus (HPV) vaccine introduction in 2006, but epidemiological and cost-effectiveness studies indicate that recommendations will need to change for fully vaccinated women. We evaluated physician intentions regarding HPV vaccine's impact on future screening.

METHODS

A nationally representative sample of 1212 primary care physicians was surveyed in 2006-2007 (response rate: 67.5%). Our study included 1114 physicians who provided Pap testing. Questions covered Pap test screening practices and intentions regarding HPV vaccine's impact on screening. Distribution differences were assessed using chi(2) statistics; multivariate analyses were performed.

RESULTS

Overall, 40.7% (95% confidence interval (CI): 37.6-43.8%) of physicians agreed that the HPV vaccine will affect screening initiation, and 38.2% (35.0-41.5%) agreed that vaccination will affect screening frequency. Significant differences in responses were found by specialty; internists were more likely to agree that vaccination would impact screening than other specialties. Belief in the effectiveness of new screening technologies was associated with intention to change screening initiation (odds ratio (OR) = 1.66 (1.20-2.31)) and frequency (OR = 1.99 (1.40-2.83)). Adherence to current Pap test screening interval guidelines was associated with intention to change screening frequency (OR = 1.39 (1.01-1.91)).

CONCLUSIONS

Many providers anticipate adjusting screening for vaccinated women, but a significant group believes nothing will change or are unsure. The present study provides important baseline data on intentions in the period preceding widespread vaccine diffusion and may help explain current and future trends in practice patterns.

Human papillomavirus vaccine introduction in Vietnam: formative research findings

BACKGROUND

Formative research is a useful tool for designing new health interventions. This paper presents key findings from formative research conducted in Vietnam to guide human papillomavirus (HPV) vaccine introduction.

METHODS

We explored the sociocultural environment, health system capacity and the policy-making process using a combined quantitative and qualitative methodology. Data collection was done through literature review, in-depth interviews, focus group discussions, observation checklists and a structured questionnaire on knowledge, attitudes and practices. Populations of interest included 11- to 14-year-old girls, their parents, community leaders, teachers, health workers, health and education officials, and policy-makers at all levels.

RESULTS

Although HPV vaccines are new, we found high potential acceptance among parents and girls. HPV vaccine introduction was also favourably supported by health professionals if assurances for system preparedness, e.g. cold chain and human resources, were made. There were no significant barriers from the policy perspective that would prevent the introduction of a new vaccine. However, several concerns related to this new vaccine would need to be adequately addressed before implementation.

CONCLUSION

Our findings provide options for potential vaccine delivery strategies, appropriate communication strategies and targeted advocacy strategies to introduce HPV vaccines in the Vietnamese context.

Monitoring of human papillomavirus vaccination

Persistent infection with oncogenic human papillomavirus (HPV) is a necessary causal factor in the development of cervical cancer. Moreover, HPV, predominately type 16 and to a lesser degree type 18, is linked causally to varying proportions of other anogenital cancers (vulva, vagina, penis, anus) as well as cancers elsewhere in the body (oropharynx, larynx, conjunctiva). HPV types 6 and 11 cause most of genital warts and recurrent respiratory papillomatosis. Effective prophylactic vaccines have been developed. In this review, we address briefly the immunological aspects of HPV infection and the results of HPV vaccination trials. Internationally standardized monitoring and evaluation of prophylactic HPV vaccination programmes will be essential for arriving at the most cost-effective strategies for cancer control.

Making evidence work for communities: the role of nongovernmental organizations in translating science to programs

Evidence-informed public health refers to the process of applying proven interventions within the context of community preferences in order to achieve positive health impacts. A key role for nongovernmental organizations (NGOs) in evidence-informed public health is to use and expand on research to help shape appropriate interventions for diverse communities. This article suggests that NGOs are particularly well positioned for this role for a number of reasons, including their geographic reach, their engagement with diverse stakeholders, and their extragovernmental position, which enables them to develop and advocate for innovative, scientifically sound solutions to long-standing health challenges. Three case studies are presented that highlight how NGOs can harness these advantages to shape evidence-informed policies and programs to improve women's health: PATH's multicountry HPV Vaccines project, the International Consortium for Emergency Contraception, and a collaborative effort to combat maternal mortality in Mali.

HPV vaccine acceptance, utilization and expected impacts in the U.S.: Where are we now?

Human papillomavirus (HPV) vaccines represent a remarkable opportunity for the primary prevention of cervical cancer and other HPV-related diseases. With almost four years of vaccine availability now accrued in the United States (U.S.), data are beginning to accumulate about vaccine utilization patterns and how these may be affected by public opinions about the vaccines. This article describes the burden of HPV infection and related disease in the U.S., and reviews what is currently known about HPV vaccine utilization among adolescent and young adult females in this country. In addition, we report on emerging data on the personal and attitudinal factors that appear to influence HPV vaccine utilization and discuss how these data may be useful for designing future interventions to improve uptake of these vaccines. Finally, we re-examine cost-effectiveness studies of HPV vaccines, taking into account updated information on utilization of, and public attitudes about, these vaccines.

Human papillomavirus vaccine update

With the approval of Gardasil (Merck and Co., Inc., Whitehouse Station, NJ) in June of 2006 and the pending approval of Cervarix (GlaxoSmithKline, London, UK), two prophylactic human papillomavirus (HPV) vaccines will be available for clinical use. Randomized controlled trials have shown that both vaccines are safe and highly effective in preventing persistent infection and lesions caused by HPV 16 and 18--the types responsible for 70% of cervical cancers worldwide. Determining an effective vaccination strategy is now the most pressing issue facing clinicians, parents, public health officials, and policy makers. We discuss the appropriate age of vaccination, vaccine acceptance, implementation strategies in low resource settings, and the future of screening.

A population-based evaluation of a publicly funded, school-based HPV vaccine program in British Columbia, Canada: parental factors associated with HPV vaccine receipt

BACKGROUND

Information on factors that influence parental decisions for actual human papillomavirus (HPV) vaccine receipt in publicly funded, school-based HPV vaccine programs for girls is limited. We report on the level of uptake of the first dose of the HPV vaccine, and determine parental factors associated with receipt of the HPV vaccine, in a publicly funded school-based HPV vaccine program in British Columbia, Canada.

METHODS AND FINDINGS

All parents of girls enrolled in grade 6 during the academic year of September 2008-June 2009 in the province of British Columbia were eligible to participate. Eligible households identified through the provincial public health information system were randomly selected and those who consented completed a validated survey exploring factors associated with HPV vaccine uptake. Bivariate and multivariate analyses were conducted to calculate adjusted odds ratios to identify the factors that were associated with parents' decision to vaccinate their daughter(s) against HPV. 2,025 parents agreed to complete the survey, and 65.1% (95% confidence interval [CI] 63.1-67.1) of parents in the survey reported that their daughters received the first dose of the HPV vaccine. In the same school-based vaccine program, 88.4% (95% CI 87.1-89.7) consented to the hepatitis B vaccine, and 86.5% (95% CI 85.1-87.9) consented to the meningococcal C vaccine. The main reasons for having a daughter receive the HPV vaccine were the effectiveness of the vaccine (47.9%), advice from a physician (8.7%), and concerns about daughter's health (8.4%). The main reasons for not having a daughter receive the HPV vaccine were concerns about HPV vaccine safety (29.2%), preference to wait until the daughter is older (15.6%), and not enough information to make an informed decision (12.6%). In multivariate analysis, overall attitudes to vaccines, the impact of the HPV vaccine on sexual practices, and childhood vaccine history were predictive of parents having a daughter receive the HPV vaccine in a publicly funded school-based HPV vaccine program. By contrast, having a family with two parents, having three or more children, and having more education was associated with a decreased likelihood of having a daughter receive the HPV vaccine.

CONCLUSIONS

This study is, to our knowledge, one of the first population-based assessments of factors associated with HPV vaccine uptake in a publicly funded school-based program worldwide. Policy makers need to consider that even with the removal of financial and health care barriers, parents, who are key decision makers in the uptake of this vaccine, are still hesitant to have their daughters receive the HPV vaccine, and strategies to ensure optimal HPV vaccine uptake need to be employed.

Cost-effectiveness analysis of a quadrivalent human papilloma virus vaccine in Mexico

BACKGROUND AND AIMS

Cervical cancer is one of the main causes of death in women in low- and middle-income countries. Despite technological and scientific advances that allow an early detection of precancerous lesions and curative treatment of cervical cancer, Mexico and other Latin American countries have only been able to obtain a small decrease in the mortality rates for this kind of cancer. How to implement and sustain effective public health strategies for cervical cancer prevention, such as increasing cytology-based screening program coverage and implementing HPV-DNA testing and vaccination, are important questions. The aim of this study is to perform a cost-effectiveness analysis of the introduction of a quadrivalent (HPV 6/11/16/18) HPV vaccine into the public health system and evaluate the epidemiological and economic benefits on prevention of cervical cancer in Mexico.

METHODS

A Markov model is used to simulate the natural history of HPV infection in a cohort of Mexican women to evaluate the cost-effectiveness of the cervical cancer screening strategy used in Mexico as well as the benefits of other potential strategies such as 1) vaccination only, 2) conventional cytology-based screening program only and 3) vaccination followed by screening. For the strategies that involve screening we have chosen screening intervals of 3 and 5 years. The model produces results that are reasonably close to the epidemiological data related to HPV and cervical cancer in Mexico.

RESULTS

The quadrivalent HPV vaccine could reduce the probability of persistent HPV-16/18 infection by at least 60%, which would result in a near-proportional reduction in HPV-16/18-associated invasive cervical cancer and CIN 3.

CONCLUSIONS

The strategy of using only vaccination ($45 USD for three doses) as a preventive measure was a very cost-effective strategy in Mexico ($68USD/LYS). The strategy of vaccination with traditional screening of Pap test every 3 years produced higher cost by a lower performance of cervical cytology in Mexico, at a cost of $15,935 USD per life-year. The cost-effectiveness of the vaccination strategy was highly sensitive to age of vaccination, duration of vaccine efficacy, and cost of vaccination. The Mexican model predicts that a quadrivalent HPV vaccine will reduce the incidence of high- and low-risk-associated cervical cancer. A program of vaccination as a preventive strategy is likely cost effective. The results of this study could be of great value in decision-making for the implementation of an HPV vaccine as a public health policy in Mexico provided that the cost of each dose will be, at most, $15 dollars (USD) dollars, combined with HPV testing, the new strategy of national secondary prevention program.