Evaluating human papillomavirus vaccination programs

Human papillomavirus vaccine: a paradigm shift for pediatricians

PURPOSE OF REVIEW

Recommendations for human papillomavirus (HPV) vaccination during adolescence primarily for a disease, cancer, that occurs only during adulthood is a paradigm shift for pediatricians. Additional postlicensure data and guidelines about HPV biology and epidemiology, disease association, adverse effects, vaccination during pregnancy, and cost-benefit analyses are now available to inform pediatricians and guide HPV vaccination recommendations.

RECENT FINDINGS

The prespecified, end-of-study combined analysis of HPV vaccine efficacy studies for prevention of cervical cancer, and now also for prevention of vulvar and vaginal cancers, confirmed 98-100% vaccine efficacy. Postlicensure surveillance identified a new association of vaccine administration with syncope, and provides assurance of the safety of inadvertent vaccination during pregnancy. Several cost-effectiveness analyses consistently demonstrated that HPV vaccination of 12-year-old girls and catch-up vaccination through 18 years of age, and possibly to 26 years of age, is cost-effective, although the thresholds of affordability vary by study. The downward trend in age of initial HPV infection and the need to educate parents and patients about HPV disease and vaccination underscore the essential role of pediatricians in managing HPV illness.

SUMMARY

It is critical for pediatricians to thoroughly understand HPV biology and disease and champion HPV vaccination to prevent cervical, vulvar, and vaginal cancers, even though these benefits accrue during adulthood and will likely require 2-4 decades to realize the financial and public health benefits. Several new developments are expected in the near future, including licensure for use in boys and men and the approval of a second, bivalent HPV vaccine.

Effectiveness and cost effectiveness of human papillomavirus vaccine: a systematic review

The recent approval of human papillomavirus (HPV) vaccine means that decision makers need information beyond that available from randomized clinical trials to recommend funding for this vaccination programme. Modelling and economic studies have addressed some of those information needs. We conducted a qualitative systematic review to summarize the existing data. Review articles were obtained from an extensive literature search on studies using mathematical modelling (either a Markov or transmission dynamic model) to determine the effectiveness or cost effectiveness of an HPV vaccine compared with the current cytology-based Pap smear screening programme. A total of 21 studies (but 22 models) were included in the review after being assessed for methodological quality. All of the included studies had used a mathematical model to determine the effectiveness of an HPV vaccine, whilst 13 had also conducted a cost-effectiveness analysis. Although the studies used different model structures, baseline parameters and assumptions, all studies showed that vaccination would decrease rates of HPV infection, precancerous lesions and cervical cancer. Studies had a consistent message with respect to cost effectiveness: a female-only vaccination programme is cost effective compared with the current cytology-based Pap smear screening programme, while the cost effectiveness of a male and female vaccination programme is generally not cost effective compared with female-only vaccination.

Modeling cervical cancer prevention in developed countries

Cytology-based screening has reduced cervical cancer mortality in countries able to implement, sustain and financially support organized programs that achieve broad coverage. These ongoing secondary prevention efforts considerably complicate the question of whether vaccination against human papillomavirus (HPV) types 16 and 18 should be introduced. Policy questions focus primarily on the target ages of vaccination, appropriate ages for a temporary "catch-up" program, possible revisions in screening policies to optimize synergies with vaccination, including the increased used of HPV DNA testing, and the inclusion of boys in the vaccination program. Decision-analytic models are increasingly being developed to simulate disease burden and interventions in different settings in order to evaluate the benefits and cost-effectiveness of primary and secondary interventions for informed decision-making. This article is a focused review on existing mathematical models that have been used to evaluate HPV vaccination in the context of developed countries with existing screening programs. Despite variations in model assumptions and uncertainty in existing data, pre-adolescent vaccination of girls has been consistently found to be attractive in the context of current screening practices, provided there is complete and lifelong vaccine protection and widespread vaccination coverage. Questions related to catch-up vaccination programs, potential benefits of other non-cervical cancer outcomes and inclusion of boys are subject to far more uncertainty, and results from these analyses have reached conflicting conclusions. Most analyses find that some catch-up vaccination is warranted but becomes increasingly unattractive as the catch-up age is extended, and vaccination of boys is unlikely to be cost-effective if reasonable levels of coverage are achieved in girls or coverage among girls can be improved. The objective of this review is to highlight points of consensus and qualitative themes, to discuss the areas of divergent findings, and to provide insight into critical decisions related to cervical cancer prevention.

Preventing cervical cancer : overviews of the National Breast and Cervical Cancer Early Detection Program and 2 US immunization programs

Three federal programs with the potential to reduce cervical cancer incidence, morbidity, and mortality, especially among underserved populations, are administered by the Centers for Disease Control and Prevention (CDC): the National Breast and Cervical Cancer Early Detection Program (NBCCEDP), the Vaccines for Children (VFC) Program, and the Section 317 immunization grant program. The NBCCEDP provides breast and cervical cancer screening and diagnostic services to uninsured and underinsured women. The VFC program and the Section 317 immunization grant program provide vaccines, including human papillomavirus (HPV) vaccine, to targeted populations at no cost for these vaccines. This article describes the programs, their histories, populations served, services offered, and roles in preventing cervical cancer through HPV vaccination and cervical cancer screening. Potential long-term reduction in healthcare costs resulting from HPV vaccination is also discussed. As an example of an initiative to vaccinate uninsured women aged 19-26 years through a cancer services program, a state-based effort that was recently launched in New York, is highlighted.

Integrating epidemiology, psychology, and economics to achieve HPV vaccination targets

Human papillomavirus (HPV) vaccines provide an opportunity to reduce the incidence of cervical cancer. Optimization of cervical cancer prevention programs requires anticipation of the degree to which the public will adhere to vaccination recommendations. To compare vaccination levels driven by public perceptions with levels that are optimal for maximizing the community's overall utility, we develop an epidemiological game-theoretic model of HPV vaccination. The model is parameterized with survey data on actual perceptions regarding cervical cancer, genital warts, and HPV vaccination collected from parents of vaccine-eligible children in the United States. The results suggest that perceptions of survey respondents generate vaccination levels far lower than those that maximize overall health-related utility for the population. Vaccination goals may be achieved by addressing concerns about vaccine risk, particularly those related to sexual activity among adolescent vaccine recipients. In addition, cost subsidizations and shifts in federal coverage plans may compensate for perceived and real costs of HPV vaccination to achieve public health vaccination targets.

Structural differences among cost-effectiveness models of human papillomavirus vaccines

In this article we compare previously published cost-effectiveness studies of human papillomavirus (HPV) vaccines along a defined subset of key model structural assumptions relating to HPV infection and disease, cervical cancer screening and HPV vaccination. For each structural aspect examined, we summarize assumptions from each study, provide a critical review and discuss the impact upon results. Considerable variation was observed across HPV vaccine cost-effectiveness models in a number of influential assumptions. Holding constant factors for which current data are lacking, the combined impact of assumptions made for the remaining parameters examined would appear to tend toward underestimation of the cost-effectiveness of HPV vaccination within existing studies. However, uncertainty concerning parameters, such as the duration of vaccine protection and acquired immunity following HPV infection, and the relationship between age and HPV virulence, complicates precise estimation of the cost-effectiveness of HPV vaccination and rigorous evaluation of the validity of existing modeling results.

Chapter 2: The burden of HPV-related cancers

On the basis of current evidence regarding human papillomavirus (HPV) and cancer, this chapter provides estimates of the global burden of HPV-related cancers, and the proportion that are actually "caused" by infection with HPV types, and therefore potentially preventable. We also present trends in incidence and mortality of these cancers in the past, and consider their likely future evolution.

Health and economic implications of HPV vaccination in the United States

BACKGROUND

The cost-effectiveness of prophylactic vaccination against human papillomavirus types 16 (HPV-16) and 18 (HPV-18) is an important consideration for guidelines for immunization in the United States.

METHODS

We synthesized epidemiologic and demographic data using models of HPV-16 and HPV-18 transmission and cervical carcinogenesis to compare the health and economic outcomes of vaccinating preadolescent girls (at 12 years of age) and vaccinating older girls and women in catch-up programs (to 18, 21, or 26 years of age). We examined the health benefits of averting other HPV-16-related and HPV-18-related cancers, the prevention of HPV-6-related and HPV-11-related genital warts and juvenile-onset recurrent respiratory papillomatosis by means of the quadrivalent vaccine, the duration of immunity, and future screening practices.

RESULTS

On the assumption that the vaccine provided lifelong immunity, the cost-effectiveness ratio of vaccination of 12-year-old girls was $43,600 per quality-adjusted life-year (QALY) gained, as compared with the current screening practice. Under baseline assumptions, the cost-effectiveness ratio for extending a temporary catch-up program for girls to 18 years of age was $97,300 per QALY; the cost of extending vaccination of girls and women to the age of 21 years was $120,400 per QALY, and the cost for extension to the age of 26 years was $152,700 per QALY. The results were sensitive to the duration of vaccine-induced immunity; if immunity waned after 10 years, the cost of vaccination of preadolescent girls exceeded $140,000 per QALY, and catch-up strategies were less cost-effective than screening alone. The cost-effectiveness ratios for vaccination strategies were more favorable if the benefits of averting other health conditions were included or if screening was delayed and performed at less frequent intervals and with more sensitive tests; they were less favorable if vaccinated girls were preferentially screened more frequently in adulthood.

CONCLUSIONS

The cost-effectiveness of HPV vaccination will depend on the duration of vaccine immunity and will be optimized by achieving high coverage in preadolescent girls, targeting initial catch-up efforts to women up to 18 or 21 years of age, and revising screening policies.

Seroepidemiology as basis for design of a human papillomavirus vaccination program

We have performed a serological survey of HPV type 16-antibody prevalence by age and sex in Sweden and used it as a basis for modelling the optimal vaccination strategies in this population. Samples of 3,317 subjects were tested for HPV16-specific antibodies. The observed age-specific seroprevalences along with sexual behaviour data were used to infer parameter values for a mathematical model representing Sweden and the preventive effect of possible strategies estimated. By the year 2055, vaccination of females starting at age 12 in 2008 was most efficient, estimated to prevent 5.8 million cumulative HPV16 infections. Catch-up programs had a strong additional preventive effect. Vaccination also targeting males increased protective effect by about 4%, but had lower preventive effect per vaccination given. Addition of an HPV serosurvey to existing models and data has enabled us to estimate effect of different vaccination strategies, optimized to the HPV epidemiology in our population.

A critique of criteria for evaluating vaccines for inclusion in mandatory school immunization programs

Several new vaccines for children and young adults have been introduced recently and now appear on the Advisory Committee on Immunization Practices' recommended childhood and adolescent immunization schedule (meningococcal, rotavirus, human papillomavirus). As new vaccines are introduced, states face complex decisions regarding which vaccines to fund and which vaccines to require for school or child care entry. This complexity is evidenced by the current debate surrounding the human papillomavirus vaccine. We present a critique to the approach and criteria for evaluating vaccines for inclusion in mandatory school immunization programs that have been adopted by the Washington State Board of Health by illustrating how these criteria might be applied to the human papillomavirus vaccine. We conclude that these 9 criteria can help ensure a deliberate and informed approach to important public policy decisions, but we argue that several clarifications of the review process are needed along with the addition of a 10th criterion that ensures that a new vaccine mandate relates in some manner to increasing safety in the school environment.

Human papillomavirus and vaccination: knowledge, attitudes, and behavioural intention in adolescents and young women in Italy

This study assesses knowledge, attitudes, and behavioural intention towards human papillomavirus (HPV) infection and vaccination in a random sample of 1348 adolescents and young women aged 14–24 years in Italy. A self-administered anonymous questionnaire covered demographics; knowledge about HPV infection, cervical cancer, and HPV vaccine; the perceived risk for contracting HPV infection and/or for developing cervical cancer, the perceived benefits of a vaccination to prevent cervical cancer, and willingness to receive an HPV vaccine. Only 23.3% have heard that HPV is an infection of the genital mucosa and about cervical cancer. Those older, with at least one parent who is a health care professional, with personal, familiar, or friendly history of cervical cancer, and having underwent a health checkup in the last year with information about HPV vaccination were significantly more knowledgeable. Risk perception scores (range: 1–10) of contracting HPV infection and of developing cervical cancer were 5.8 and 6.5. Older age, not having a parent who is a health care professional, having had a personal, familiar, or friendly history of cervical cancer, and need of additional information were predictors of the perceived susceptibility of developing cervical cancer. The vast majority professed intent to receive an HPV vaccine and the significant predictors were having at least one parent who is a health care professional, a high perceived risk of contracting HPV infection and of developing cervical cancer, and a high belief towards the utility of a vaccination for preventing cervical cancer. Knowledge about HPV infection and cervical cancer should be improved with more attention to the benefit of HPV vaccination.

Long-term clinical impact of introducing a human papillomavirus 16/18 AS04 adjuvant cervical cancer vaccine in Spain

BACKGROUND

Human papillomavirus (HPV) epidemiology and screening practices vary considerably between countries and specific analyses are required to estimate the impact of HPV vaccination. This study aimed to predict the clinical benefits of introducing a bivalent HPV16/18 vaccine in Spain, where the cervical cancer (CC) incidence is 10.3 per 100 000.

METHODS

A Markov model based upon the natural history of HPV and CC was developed to simulate transitions between health states, in the presence of specific screening programmes. Published data were used to reflect the Spanish situation in terms of epidemiological characteristics, screening and treatment practices. Calibration consisted of varying disease progression rates within established ranges until model predictions matched observed epidemiological data. The clinical impact of vaccinating a cohort of 12-year-old girls against HPV was assessed over their lifetime using the calibrated model.

RESULTS

Vaccination of all 12-year-old girls would result in a reduction of 75% (from 0.32% to 0.08%) in the prevalence of high-grade precancerous lesions due to oncogenic HPV, and a 79% reduction in both CC cases (from 1745 to 365) and CC deaths (from 417 to 86). Assuming a vaccine coverage of 80%, the number of CC cases and deaths would decrease by 63%. Vaccination could also substantially reduce the number of screening tests and treatments required for cervical dysplasia.

CONCLUSION

Our model was successfully adapted to the Spanish epidemiological environment, screening and treatment practices and predicted a substantial long-term benefit of HPV vaccination despite a low HPV prevalence in Spain.

The current and future role of screening in the era of HPV vaccination

With the introduction of cervical screening programs, the incidence and mortality of cervical cancer has been drastically reduced. Techniques such as the traditional Papanicolaou test and the newer liquid-based cytology allow for the early detection of cervical abnormalities prior to the development of invasive cervical cancer. As oncogenic human papillomavirus (HPV) infection is necessary for cervical cancer, HPV-DNA testing has also been proposed as a routine screening method for the general population. Screening limitations, such as adherence, test sensitivity and specificity, access, and cost-effectiveness are reflected in current screening guidelines. The development of prophylactic cervical cancer vaccines is a major milestone in cervical cancer prevention. These vaccines protect against the initial infection of certain oncogenic HPV types, and therefore prevent the development of cervical dysplasia, precancerous lesions, and cervical cancer. Considering routine cervical cancer vaccination in adolescent girls, screening guidelines must adapt in order to retain efficient and cost-effective prevention measures. Although the true epidemiological and economic impact of cervical cancer vaccines cannot be immediately realized, mathematical models predict various scenarios in which vaccination, in addition to cervical screening, will be cost-effective and further reduce cervical cancer disease.

The human papillomavirus vaccine in Canada

Clinical studies have shown the human papillomavirus (HPV) vaccines to be very effective at preventing persistent infection by vaccine serotypes. The development of these new vaccines heralds a new era in cancer prevention. Gardasil, Merck's quadravalent HPV vaccine, has recently been licensed in Canada for women aged 9 to 26 years of age. It necessitates that health professionals become familiar with the vaccine, the evidence supporting its effectiveness and issues related to vaccine strategy, cost effectiveness, and remaining research questions. The vaccine is recommended in Canada for females aged 9 to 13 years and should also be offered to females aged 14 to 26 years. Ongoing research will determine the duration of protection conferred by the vaccine, and the potential need for booster doses. In conjunction with continued screening programs, the HPV vaccine offers the potential to dramatically reduce the burden of cervical cancer in Canada, and to do so in a cost-effective manner.

The HPV vaccine: framing the arguments FOR and AGAINST mandatory vaccination of all middle school girls

BACKGROUND

Human papillomavirus (HPV), the virus responsible for cervical cancer, is the most common viral sexually transmitted infection in the United States. A vaccine was approved in 2006 that is effective in preventing the types of HPV responsible for 70% of cervical cancers and 90% of genital warts. Proposals for routine and mandatory HPV vaccination of girls have become sources of controversy for parents of school-aged youth, legislators, members of the medical community, and the public at large.

METHODS

The purpose of this article was to articulate the arguments used by advocates who either oppose or endorse routine, mandatory administration of the vaccine to school-aged girls, thereby assisting school health personnel in being effective participants in framing the relevant issues.

RESULTS

Controversy is grounded in moral, religious, political, economic, and sociocultural arguments including whether concerns that the vaccine increases sexual risk taking, sends mixed messages about abstaining from sexual intercourse, usurps parental authority, and increases the potential for development of new health disparities are offset by the value of administering a cost-effective, age-appropriate public health measure targeting a life-threatening problem.

CONCLUSIONS

Careful consideration of the medical evidence and public health implications is critical but understanding the context of the debate is no less important to the task of responding to public concerns. School health personnel have a role in the discussion about HPV immunization. Being able to articulate the arguments presented herein can help authorities' responsiveness to parents and community groups as the dialogue about this particular health issue evolves further.

Cost-effectiveness of human papillomavirus vaccination in the United States

Results of a simplified model were consistent with published studies based on more complex models when key assumptions were similar.

We describe a simplified model, based on the current economic and health effects of human papillomavirus (HPV), to estimate the cost-effectiveness of HPV vaccination of 12-year-old girls in the United States. Under base-case parameter values, the estimated cost per quality-adjusted life year gained by vaccination in the context of current cervical cancer screening practices in the United States ranged from $3,906 to $14,723 (2005 US dollars), depending on factors such as whether herd immunity effects were assumed; the types of HPV targeted by the vaccine; and whether the benefits of preventing anal, vaginal, vulvar, and oropharyngeal cancers were included. The results of our simplified model were consistent with published studies based on more complex models when key assumptions were similar. This consistency is reassuring because models of varying complexity will be essential tools for policy makers in the development of optimal HPV vaccination strategies.

The human papillomavirus vaccine in Canada

Clinical studies have shown the human papillomavirus (HPV) vaccines to be very effective at preventing persistent infection by vaccine serotypes. The development of these new vaccines heralds a new era in cancer prevention. Gardasil, Merck's quadravalent HPV vaccine, has recently been licensed in Canada for women aged 9 to 26 years of age. It necessitates that health professionals become familiar with the vaccine, the evidence supporting its effectiveness and issues related to vaccine strategy, cost effectiveness, and remaining research questions. The vaccine is recommended in Canada for females aged 9 to 13 years and should also be offered to females aged 14 to 26 years. Ongoing research will determine the duration of protection conferred by the vaccine, and the potential need for booster doses. In conjunction with continued screening programs, the HPV vaccine offers the potential to dramatically reduce the burden of cervical cancer in Canada, and to do so in a cost-effective manner.

Parental acceptance of Human Papillomavirus vaccines

OBJECTIVE

To determine whether parents would accept Human Papillomavirus (HPV) vaccination for their children and which variables may influence their decision, including knowledge about cervical cancer and HPV.

STUDY DESIGN

Three hundred and fifty-six parents of children aged 10-12 years were interviewed regarding the acceptance of an HPV vaccine for their children and their knowledge of HPV and cervical cancer. All data were recorded anonymously. Results were compared using the chi(2)- and the Mann-Whitney test.

RESULTS

HPV vaccination would be accepted by 88% of the parents, preferably when the child is aged 10-12 years. Parents of children who received all the vaccinations of the National Vaccination Programme accepted HPV vaccination significantly more. Less than a third of all parents had heard of HPV, and 14% were aware of the causal relationship of HPV and cervical cancer. Knowledge of HPV and cervical cancer, religion, age, education, and marital status did not show any significant relation with HPV vaccine acceptance.

CONCLUSIONS

A majority of the parents would accept HPV vaccination. HPV vaccine acceptance seems to be dependent on vaccine acceptance in general, even more than on knowledge of HPV and its causal relation with cervical cancer. However, parents requested more information about cervical cancer, HPV, and HPV vaccination, before the HPV vaccine is introduced.

Economics of an adolescent meningococcal conjugate vaccination catch-up campaign in the United States

BACKGROUND

In June 2005, the Advisory Committee on Immunization Practices recommended the newly licensed quadrivalent meningococcal conjugate vaccine for routine use among all US children aged 11 years. A 1-time catch-up vaccination campaign for children and adolescents aged 11-17 years, followed by routine annual immunization of each child aged 11 years, could generate immediate herd immunity benefits. The objective of our study was to analyze the cost-effectiveness of a catch-up vaccination campaign with quadrivalent meningococcal conjugate vaccine for children and adolescents aged 11-17 years.

METHODS

We built a probabilistic model of disease burden and economic impacts for a 10-year period with and without a program of adolescent catch-up meningococcal vaccination, followed by 9 years of routine immunization of children aged 11 years. We used US age- and serogroup-specific surveillance data on incidence and mortality. Assumptions related to the impact of herd immunity were drawn from experience with routine meningococcal vaccination in the United Kingdom. We estimated costs per case, deaths prevented, life-years saved, and quality-adjusted life-years saved.

RESULTS

With herd immunity, the catch-up and routine vaccination program for adolescents would prevent 8251 cases of meningococcal disease in a 10-year period (a 48% decrease). Excluding program costs, this catch-up and routine vaccination program would save US$551 million in direct costs and $920 million in indirect costs, including costs associated with permanent disability and premature death. At $83 per vaccinee, the catch-up vaccination would cost society approximately $223,000 per case averted, approximately $2.6 million per death prevented, approximately $127,000 per life-year saved, and approximately $88,000 per quality-adjusted life-year saved. Targeting counties with a high incidence of disease decreased the cost per life-year saved by two-thirds.

CONCLUSIONS

Although costly, catch-up and routine vaccination of adolescents can have a substantial impact on meningococcal disease burden. Because of herd immunity, catch-up and routine vaccination cost per life-year saved could be up to one-third less than that previously assessed for routine vaccination of children aged 11 years.

Moving forward: human papillomavirus vaccination and the prevention of cervical cancer

In June 2006, the Food and Drug Administration (FDA) approved the first human papillomavirus (HPV) vaccine. The vaccine was subsequently recommended by the Centers for Disease Control and Prevention's (CDC) Advisory Committee for Immunization Practices (ACIP) for routine vaccination of 11-12-year-old girls and catch-up vaccination of females 13-26 years of age. With the approval of the first HPV vaccine, cervical cancer now has a primary prevention tool. However, the availability of an HPV vaccine will not change the course of cervical cancer in this country unless there is both widespread demand by and access for the targeted populations. Demand will require recognition of the need for protection against HPV infection as well as a positive perception of the vaccine as safe and efficacious. General knowledge of HPV and its relationship to cervical cancer is limited; some parents and healthcare providers are hesitant to vaccinate preadolescent girls. Access to the expensive vaccine will not be increased without addressing financial constraints. Although the Vaccines for Children (VFC) program has added HPV to its vaccine plan, not all private insurers have approved coverage, and the uninsured and underinsured may have limited access. Moving forward will require a well-planned and executed public information campaign by trusted sources and the development of a comprehensive vaccine administration program. Although mandates would assure the broadest coverage, controversies surrounding mandates may deter work toward broad coverage. States should focus on developing a comprehensive program and then return to the mandate issue if coverage does not meet public health objectives.

Appropriate Use of Cervical Cancer Vaccine

Human papillomavirus (HPV) is a necessary, though not sufficient, cause of cervical cancer. Two vaccines have been developed that prevent two HPV types associated with 70% of cervical cancers. One of the vaccines (a quadrivalent vaccine) also prevents two HPV types associated with 90% of genital warts. Both HPV vaccines have shown very good efficacy and safety. This review summarizes the guidelines for use of the quadrivalent vaccine published by the Advisory Committee on Immunization Practices, presents data on vaccine efficacy and safety, and gives an overview of the findings of cost-effectiveness studies. In addition, we summarize the research on the attitudes of parents and health care providers toward HPV vaccine and critically evaluate controversial and challenging issues surrounding HPV vaccination, including concerns about sexual disinhibition and potential obstacles to vaccine distribution and uptake.

A cost-effectiveness analysis of adding a human papillomavirus vaccine to the Australian National Cervical Cancer Screening Program

BACKGROUND

The cost-effectiveness of adding a human papillomavirus (HPV) vaccine to the Australian National Cervical Screening Program compared to screening alone was examined.

METHODS

A Markov model of the natural history of HPV infection that incorporates screening and vaccination was developed. A vaccine that prevents 100% of HPV 16/18-associated disease, with a lifetime duration of efficacy and 80% coverage offered through a school program to girls aged 12 years, in conjunction with current screening was compared with screening alone using cost (in Australian dollars) per life-year (LY) saved and quality-adjusted life-year (QALY) saved. Sensitivity analyses included determining the cost-effectiveness of offering a catch-up vaccination program to 14-26-year-olds and accounting for the benefits of herd immunity.

RESULTS

Vaccination with screening compared with screening alone was associated with an incremental cost-effectiveness ratio (ICER) of $51 103 per LY and $18 735 per QALY, assuming a cost per vaccine dose of $115. Results were sensitive to assumptions about the duration of vaccine efficacy, including the need for a booster ($68 158 per LY and $24 988 per QALY) to produce lifetime immunity. Accounting for herd immunity resulted in a more attractive ICER ($36 343 per LY and $13 316 per QALY) for girls only. The cost per LY of vaccinating boys and girls was $92 052 and the cost per QALY was $33 644. The cost per LY of implementing a catch-up vaccination program ranged from $45 652 ($16 727 per QALY) for extending vaccination to 14-year-olds to $78 702 ($34 536 per QALY) for 26-year-olds.

CONCLUSIONS

These results suggest that adding an HPV vaccine to Australia's current screening regimen is a potentially cost-effective way to reduce cervical cancer and the clinical interventions that are currently associated with its prevention via screening alone.

Projected cost-effectiveness of new vaccines for adolescents in the United States

BACKGROUND

Economic assessments that guide policy making on immunizations are becoming increasingly important in light of new and anticipated vaccines for adolescents. However, important considerations that limit the utility of these assessments, such as the diversity of approaches used, are often overlooked and should be better understood.

OBJECTIVE

Our goal was to examine economic studies of adolescent vaccines and compare cost-effectiveness outcomes among studies on a particular vaccine, across adolescent vaccines, and between new adolescent vaccines versus vaccines that are recommended for young children.

METHODS

A systematic review of economic studies on immunizations for adolescents was conducted. Studies were identified by searching the Medline, Embase, and EconLit databases. Each study was reviewed for appropriateness of model design, baseline setup, sensitivity analyses, and input variables (ie, epidemiologic, clinical, cost, and quality-of-life impact). For comparison, the cost-effectiveness outcomes reported in key studies on vaccines for younger children were selected.

RESULTS

Vaccines for healthy adolescents were consistently found to be more costly than the health care or societal cost savings they produced and, in general, were less cost-effective than vaccines for younger children. Among the new vaccines, pertussis and human papillomavirus vaccines were more cost-effective than meningococcal vaccines. Including herd-immunity benefits in studies significantly improved the cost-effectiveness estimates for new vaccines. Differences in measurements or assumptions limited further comparisons.

CONCLUSION

Although using the new adolescent vaccines is unlikely to be cost-saving, vaccination programs will result in sizable health benefits.

[Prevention of human papillomavirus (HPV)-induced infections: access of adolescent girls to health care. A population-based, cross-sectional observational study]

INTRODUCTION

The human papillomavirus (HPV) is the most common cause of sexually transmitted infections worldwide, and its prevalence is highest among young women aged 17-25 years. It is the principal risk factor for cervical cancer. Systematic vaccination of adolescent girls should significantly reduce the incidence of this disease and its related mortality.

AIM

One of the objectives of the Enjeux study, a population-based survey, was to identify the place of young girls within the French health care system to help assess the optimal conditions for implementing anti-HPV vaccination.

METHODS

Data came from 5354 interviews of women aged 18-70 years, 320 of whom provided information about daughters aged 11-14 years and 406 about daughters aged 15-17 years. Among the latter, 318 were also interviewed and 294 completed a self-administered questionnaire.

RESULTS

The results showed that sexual activity was reported by approximately one third of the girls aged 15-17 years. At-risk behaviors in these girls included insufficient contraception (only 51% use condoms). Data on the medical management of the population of 11-17 year-old girls indicate that they have access to - and are integrated into - the health care system, with frequent medical visits. They see the general practitioner (GP) most frequently, followed by the school doctor. The frequency of general practice visits is similar in both age groups; more than 50% of the girls visit their GP more than twice a year. Vaccination is a frequent reason for these visits; gynecologic reasons are less frequent.

CONCLUSION

The results of this survey underline the central place of the GP in the health management of young girls aged 11 to 17 years.

Specific viruses were not detected in Guthrie cards from children who later developed leukemia

There are hypotheses concerning infectious mechanism in the development of acute lymphoblastic leukemia (ALL). The first genetic event often happens in utero, based on studies from Guthrie cards. The authors have summarized the results from their studies concerning infectious mechanism. Presence of human polyomaviruses, parvovirus, HHV-6, EBV, and CMV were investigated by PCR from Guthrie cards from children who later developed ALL and healthy controls. Neither of these viruses were detected from patients nor from controls. The results do not support that these viruses have contributed to the development of a substantial part of the ALL cases in Swedish children.

The HPV vaccine mandate controversy

In this editorial we address the controversies surrounding human papillomavirus (HPV) vaccine school-entry mandate legislation, but differentiate between the mandate debate and issues specific to the vaccine itself. Our goal is not to take a stand in favor of or opposed to mandates, but rather to critically examine the issues. We discuss the following arguments against HPV vaccine school-entry requirements: 1. The public health benefit of mandated HPV vaccination is not sufficient to warrant the intrusion on parental autonomy; 2. A vaccine that prevents a non-casually transmitted infection should not be mandated; 3. Opt-out provisions are inherently unfair to parents who oppose HPV vaccination; 4. Limited health care dollars should not be directed toward cervical cancer prevention; and 5. The vaccine is expensive and potential problems with supply suggest that mandates should not be implemented until insurance coverage and supply issues are resolved. Next, we critically evaluate the following critiques of HPV vaccination itself: 1. Giving girls HPV vaccine implies tacit consent to engage in sexual activity; 2. Giving girls this vaccine will confer a false sense of protection from sexually transmitted infections and will lead to sexual disinhibition; 3. Children already have too many vaccinations on the immunization schedule; 4. Long-term side effects of HPV vaccine are unknown; 5. The vaccine's enduring effectiveness is unknown and booster shots may be required; and 6. It is wrong to only target girls with HPV vaccine; boys should be vaccinated as well.

The value of including boys in an HPV vaccination programme: a cost-effectiveness analysis in a low-resource setting

We assessed the cost-effectiveness of including boys vs girls alone in a pre-adolescent vaccination programme against human papillomavirus (HPV) types 16 and 18 in Brazil. Using demographic, epidemiological, and cancer data from Brazil, we developed a dynamic transmission model of HPV infection between males and females. Model-projected reductions in HPV incidence under different vaccination scenarios were applied to a stochastic model of cervical carcinogenesis to project lifetime costs and benefits. We assumed vaccination prevented HPV-16 and -18 infections in individuals not previously infected, and protection was lifelong. Coverage was varied from 0-90% in both genders, and cost per-vaccinated individual was varied from IUSD 25 to 400. At 90% coverage, vaccinating girls alone reduced cancer risk by 63%; including boys at this coverage level provided only 4% further cancer reduction. At a cost per-vaccinated individual of USD 50, vaccinating girls alone was Collapse

Key Words

• cost-effectiveness analysis, hpv vaccination, cervical cancer, mathematical models, dynamic models, computer simulation

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MESH Headings

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Brazil
• Child
• Child, Preschool
• Cost-Benefit Analysis
• Female
• Health Policy/economics
• Human papillomavirus 16/immunology
• Human papillomavirus 18/immunology
• Humans
• Infant
• Infant, Newborn
• Male
• Mass Screening/economics
• Middle Aged
• Papillomavirus Infections/diagnosis
• Papillomavirus Infections/economics
• Papillomavirus Infections/prevention & control
• Quality-Adjusted Life Years
• Uterine Cervical Neoplasms/diagnosis
• Uterine Cervical Neoplasms/economics
• Uterine Cervical Neoplasms/prevention & control
• Vaccination
• Uterine Cervical Dysplasia/diagnosis
• Uterine Cervical Dysplasia/economics
• Uterine Cervical Dysplasia/prevention & control

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Grants

• R01 CA093435 NCI NIH HHS
• R01 CA93435 NCI NIH HHS

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Affiliation(s)

J J Kim Department of Health Policy and Management, Harvard School of Public Health, Program in Health Decision Science, 718 Huntington Avenue, 2nd Floor, Boston, MA 02115, USA.
B Andres-Beck
S J Goldie

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Modeling human papillomavirus and cervical cancer in the United States for analyses of screening and vaccination

Background

To provide quantitative insight into current U.S. policy choices for cervical cancer prevention, we developed a model of human papillomavirus (HPV) and cervical cancer, explicitly incorporating uncertainty about the natural history of disease.

Methods

We developed a stochastic microsimulation of cervical cancer that distinguishes different HPV types by their incidence, clearance, persistence, and progression. Input parameter sets were sampled randomly from uniform distributions, and simulations undertaken with each set. Through systematic reviews and formal data synthesis, we established multiple epidemiologic targets for model calibration, including age-specific prevalence of HPV by type, age-specific prevalence of cervical intraepithelial neoplasia (CIN), HPV type distribution within CIN and cancer, and age-specific cancer incidence. For each set of sampled input parameters, likelihood-based goodness-of-fit (GOF) scores were computed based on comparisons between model-predicted outcomes and calibration targets. Using 50 randomly resampled, good-fitting parameter sets, we assessed the external consistency and face validity of the model, comparing predicted screening outcomes to independent data. To illustrate the advantage of this approach in reflecting parameter uncertainty, we used the 50 sets to project the distribution of health outcomes in U.S. women under different cervical cancer prevention strategies.

Results

Approximately 200 good-fitting parameter sets were identified from 1,000,000 simulated sets. Modeled screening outcomes were externally consistent with results from multiple independent data sources. Based on 50 good-fitting parameter sets, the expected reductions in lifetime risk of cancer with annual or biennial screening were 76% (range across 50 sets: 69–82%) and 69% (60–77%), respectively. The reduction from vaccination alone was 75%, although it ranged from 60% to 88%, reflecting considerable parameter uncertainty about the natural history of type-specific HPV infection. The uncertainty surrounding the model-predicted reduction in cervical cancer incidence narrowed substantially when vaccination was combined with every-5-year screening, with a mean reduction of 89% and range of 83% to 95%.

Conclusion

We demonstrate an approach to parameterization, calibration and performance evaluation for a U.S. cervical cancer microsimulation model intended to provide qualitative and quantitative inputs into decisions that must be taken before long-term data on vaccination outcomes become available. This approach allows for a rigorous and comprehensive description of policy-relevant uncertainty about health outcomes under alternative cancer prevention strategies. The model provides a tool that can accommodate new information, and can be modified as needed, to iteratively assess the expected benefits, costs, and cost-effectiveness of different policies in the U.S.

Expression of HPV-11 L1 protein in transgenic Arabidopsis thaliana and Nicotiana tabacum

BACKGROUND

We have investigated the possibility and feasibility of producing the HPV-11 L1 major capsid protein in transgenic Arabidopsis thaliana ecotype Columbia and Nicotiana tabacum cv. Xanthi as potential sources for an inexpensive subunit vaccine.

RESULTS

Transformation of plants was only achieved with the HPV-11 L1 gene with the C-terminal nuclear localization signal (NLS-) encoding region removed, and not with the full-length gene. The HPV-11 L1 NLS- gene was stably integrated and inherited through several generations of transgenic plants. Plant-derived HPV-11 L1 protein was capable of assembling into virus-like particles (VLPs), although resulting particles displayed a pleomorphic phenotype. Neutralising monoclonal antibodies binding both surface-linear and conformation-specific epitopes bound the A. thaliana-derived particles and - to a lesser degree - the N. tabacum-derived particles, suggesting that plant-derived and insect cell-derived VLPs displayed similar antigenic properties. Yields of up to 12 microg/g of HPV-11 L1 NLS- protein were harvested from transgenic A. thaliana plants, and 2 microg/g from N. tabacum plants - a significant increase over previous efforts. Immunization of New Zealand white rabbits with approximately 50 microg of plant-derived HPV-11 L1 NLS- protein induced an antibody response that predominantly recognized insect cell-produced HPV-11 L1 NLS- and not NLS+ VLPs. Evaluation of the same sera concluded that none of them were able to neutralise pseudovirion in vitro.

CONCLUSION

We expressed the wild-type HPV-11 L1 NLS- gene in two different plant species and increased yields of HPV-11 L1 protein by between 500 and 1000-fold compared to previous reports. Inoculation of rabbits with extracts from both plant types resulted in a weak immune response, and antisera neither reacted with native HPV-11 L1 VLPs, nor did they neutralise HPV-11 pseudovirion infectivity. This has important and potentially negative implications for the production of HPV-11 vaccines in plants.

Human papillomavirus vaccines in HIV-positive men and women

PURPOSE OF REVIEW

Individuals with HIV are at greater risk of human papillomavirus-related cancers. This report will assess the potential and limitations of vaccines against human papillomavirus in HIV-positive individuals.

RECENT FINDINGS

A worldwide meta-analysis of published data established the under-representation of HPV16, and increased prevalence of multiple-type human papillomavirus infections in HIV-positive women. Associations between HIV-related immunodepression, the progression of human papillomavirus infection to cervical lesions, and an increased risk of cervical cancer in women with HIV have also been shown. An increased incidence of human papillomavirus infection in anal and vulvar/vaginal neoplasia has been reported in individuals with HIV. A prophylactic vaccine against HPV6, 11, 16 and 18 has been licensed, and one against HPV16 and 18 is under evaluation. Both have shown efficacy against persistent infection, as well as related human papillomavirus cervical lesions for up to 5 years. Preliminary results have also been reported on therapeutic vaccines, notably for the treatment of cervical intraepithelial neoplasia grades 2 and 3.

SUMMARY

The safety and efficacy of human papillomavirus vaccines in individuals with HIV need to be assessed to prevent cervical cancer in current and future generations. Screening for human papillomavirus-related cancer among HIV patients should be undertaken.