Human papillomavirus vaccination and the role of herd effects in future cancer control planning: a review

Awareness of cancer among adolescents: A study of nine focus groups in Aotearoa New Zealand

ISSUE ADDRESSED

One third of cancers are potentially preventable by modifying key risk factors that arise during adolescence. To help inform prevention efforts, we investigated adolescents' understanding of cancer risk factors, symptoms and signs and barriers to help-seeking.

METHODS

Nine focus groups were conducted with purposefully sampled, binary-gendered friendship groups of 12 to 17-year-olds. Interviews were analysed using a qualitative descriptive method based on the topic schedule, transcripts and field notes.

RESULTS

Behavioural, genetic and environmental factors were commonly explored as risk factors. Most cancer symptoms identified focused on physical indicators, such as lumps and skin appearance. Facilitators and barriers to good health choices involved both external and internal factors: education, affordability, attitudes and the social environment. Most participants indicated they would talk to trusted friends and family members about health issues, but only when the condition became 'serious'. The most common source of health information was the internet.

CONCLUSIONS

Adolescents have a good understanding of behavioural risk factors, but poor knowledge of some key cancer symptoms. A support system was recognised to be a substantive factor in dealing with health issues, as were youth-focused health services. Understanding of the preventability of many cancers was not widespread with participants. SO WHAT?: The results emphasise a requirement for appropriate, affordable and accessible youth-focused health services. There is a need for age- and culturally appropriate interventions that improve knowledge of cancer symptoms. Immunisation against the viruses implicated in cervical cancer is one example of a clinical cancer prevention intervention in adolescence.

Assessing the reduction of viral infectivity in HPV16/18-positive women after one, two, and three doses of Gardasil-9 (RIFT): Study protocol

Human Papillomavirus (HPV) prophylactic vaccination has proven effective in preventing new infections, but it does not treat existing HPV infections or associated diseases. Hence, there is still an important reservoir of HPV in adults, as vaccination programs are mainly focused on young women. The primary objective of this non-randomized, open-label trial is to evaluate if a 3-dose regimen of Gardasil-9 in HPV16/18-positive women could reduce the infective capacity of their body fluids. We aim to assess if vaccine-induced antibodies could neutralize virions present in the mucosa, thus preventing the release of infective particles and HPV transmission to sexual partners. As our main endpoint, the E1^E4-HaCaT model will be used to assess the infectivity rate of cervical, anal and oral samples, obtained from women before and after vaccination. HPV DNA positivity, virion production, seroconversion, and the presence of antibodies in the exudates, will be evaluated to attribute infectivity reduction to vaccination. Our study will recruit two different cohorts (RIFT-HPV1 and RIFT-HPV2) of non-vaccinated adult women. RIFT-HPV1 will include subjects with an HPV16/18 positive cervical test and no apparent cervical lesions or cervical lesions eligible for conservative treatment. RIFT-HPV2 will include subjects with an HPV16/18 positive anal test and no apparent anal lesions or anal lesions eligible for conservative treatment, as well as women with an HPV16/18 positive cervical test and HPV-associated vulvar lesions. Subjects complying with inclusion criteria for both cohorts will be recruited to the main cohort, RIFT-HPV1. Three doses of Gardasil-9 will be administered intramuscularly at visit 1 (0 months), visit 2 (2 months) and visit 3 (6 months). Even though prophylactic HPV vaccines would not eliminate a pre-existing infection, our results will determine if HPV vaccination could be considered as a new complementary strategy to prevent HPV-associated diseases by reducing viral spread. Trial registration: https://clinicaltrials.gov/ct2/show/NCT05334706.

Epidemiology of genital human papillomavirus infections in sequential male sex partners of young females

OBJECTIVES

Couple-based studies have considered human papillomavirus (HPV) transmission between current heterosexual partners (male↔female). Using data from young women and their sequential male partners, we analysed HPV transmission from upstream sexual partnerships (male 1↔female) to downstream sex partners (→male 2).

METHODS

Among 502 females enrolled in the HPV Infection and Transmission among Couples through Heterosexual activity study (2005-2011, Montréal, Canada), 42 brought one male sex partner at baseline (male 1) and another during follow-up (male 2). Female genital samples, collected at six visits over 24 months, and male genital samples, collected at two visits over 4 months, were tested for 36 HPV types (n = 1512 detectable infections). We calculated observed/expected ratios with 95% CIs for type-specific HPV concordance between males 1 and 2. Using mixed-effects regression, we estimated ORs with 95% CIs for male 2 testing positive for the same HPV type as male 1.

RESULTS

Detection of the same HPV type in males 1 and 2 occurred 2.6 (CI 1.9-3.5) times more often than chance (29 instances observed vs. 10.95 instances expected). The OR for male 2 positivity was 4.2 (CI 2.5-7.0). Adjusting for the number of times the linking female tested positive for the same HPV type attenuated the relationship between male 1 and 2 positivity, suggesting mediation.

CONCLUSIONS

High type-specific HPV concordance between males 1 and 2 confirms HPV's transmissibility in chains of sequential sexual partnerships. HPV positivity in an upstream partnership predicted positivity in a downstream male when the linking female partner was persistently positive.

Building resilient cervical cancer prevention through gender-neutral HPV vaccination

The COVID-19 pandemic has disrupted HPV vaccination programmes worldwide. Using an agent-based model, EpiMetHeos, recently calibrated to Indian data, we illustrate how shifting from a girls-only (GO) to a gender-neutral (GN) vaccination strategy could improve the resilience of cervical cancer prevention against disruption of HPV vaccination. In the base case of 5-year disruption with no coverage, shifting from GO to GN strategy under 60% coverage (before disruption) would increase the resilience, in terms of cervical cancer cases still prevented in the disrupted birth cohorts per 100,000 girls born, by 2.8-fold from 107 to 302 cases, and by 2.2-fold from 209 to 464 cases under 90% coverage. Furthermore, shifting to GN vaccination helped in reaching the World Health Organization (WHO) elimination threshold. Under GO vaccination with 60% coverage, the age-standardised incidence rate of cervical cancer in India in the long term with vaccination decreased from 11.0 to 4.7 cases per 100,000 woman-years (above threshold), as compared to 2.8 cases (below threshold) under GN with 60% coverage and 2.4 cases (below threshold) under GN with 90% coverage. In conclusion, GN HPV vaccination is an effective strategy to improve the resilience to disruption of cancer prevention programmes and to enhance the progress towards cervical cancer elimination.

Health and economic impact of delaying large-scale HPV vaccination and screening implementation on cervical cancer in China: a modelling study

Background

Current uptake of HPV vaccination and screening in China is far below World Health Organization 2030 targets for cervical cancer elimination. We quantified health and economic losses of delaying large-scale HPV vaccination and screening implementation in China.

Methods

We used a previously validated transmission model to project lifetime health benefits, costs, effectiveness, and timeline for cervical cancer elimination of alternative scenarios, including combining HPV vaccination initiated from 2022 to 2030 with screening in different modalities and coverage increase rates, as well as screening alone. All women living or projected to be born in China during 2022-2100 were considered. We employed a societal perspective.

Findings

Regardless of vaccine type, immediate large-scale vaccination initiated in 2022 and achieving 70% coverage of HPV-based screening in 2030 (no-delay scenario) would be the least costly and most effective. Compared with the no-delay scenario, delaying vaccination by eight years would result in 434,000-543,000 additional cervical cancer cases, 138,000-178,000 deaths, and $2863-4437 million costs, and delay elimination by 9-10 years. Even with immediate vaccination, the gradual scale-up of LBC-based screening to 70% coverage in 2070 would result in 2,530,000-3,060,000 additional cases, 909,000-1,040,000 deaths, and $5098-5714 million costs compared with no-delay scenario, and could not achieve elimination if domestic 2vHPV or 4vHPV vaccines are used (4.09-4.21 cases per 100,000 woman in 2100).

Interpretation

Delaying large-scale HPV vaccination and/or high-performance screening implementation has detrimental consequences for cervical cancer morbidity, mortality, and expenditure. These findings should spur health authorities to expedite large-scale vaccine rollout and improve screening.

Funding

Bill & Melinda Gates Foundation (INV-031449 and INV-003174) and CAMS Innovation Fund for Medical Sciences (CIFMS) (2021-I2M-1-004).

Parental Justifications for Not Vaccinating Children or Adolescents against Human Papillomavirus (HPV)

Vaccination coverage against Human Papillomavirus (HPV) is low compared with uptake of other vaccines in many countries, including Brazil. The aim of this study was to examine the main reasons provided by parents or guardians of a target population that did not have the first dose of HPV vaccine in a small rural Brazilian municipality, and to verify the factors associated with the reasons for non-vaccination. This is a cross-sectional study with interviews based on the Health Belief Model (HBM), conducted with parents and guardians of 177 unvaccinated children or adolescents. The outcome of interest was the main reason for not vaccinating the child/adolescent. The exposure factors of interest were knowledge about HPV and its prevention as well as sociodemographic characteristics. The main justifications for not vaccinating were lack of information (62.2%), fear or refusal (29.9%), and logistical issues (7.9%). The justifications associated with adolescents’ sex, fear, or refusal were mentioned by 39.3% (95% CI: 28.8–50.6%) of parents or guardians of girls and by 21.5% (95% CI: 13.7–31.2%) of parents or guardians of boys. The main barrier to HPV vaccination is lack of information. Further training of health professionals in clarifying the benefits of vaccination and differentiating the risks between boys and girls could encourage uptake.

A review of ethical and legal aspects of gender-neutral human papillomavirus vaccination

While launching a campaign to eliminate cervical cancer, the World Health Organization called to halt human papillomavirus (HPV) gender-neutral vaccination (GNV) because of limited vaccine supply, raising ethical and legal questions about female-only vaccination versus GNV. We identified ethical and legal aspects of HPV GNV by searching MEDLINE for records up to February 19, 2021. We also provided an overview of HPV vaccines, the evolution of HPV vaccine recommendations in North America, and a timeline of male HPV vaccination introduction by searching PubMed, Google, and government websites. Four HPV vaccines are available: Cervarix®, Gardasil®, Gardasil®9, and Cecolin®. Vaccine recommendations in North America evolved from female only to eventually include males. Following the Food and Drug Administration's approval of the first HPV vaccine for males (2009), 35 countries began vaccinating males (2011-2020). Based on 56 eligible records out of 652, we identified the following constructs: lower male awareness of HPV and vaccination (n=13), limited economic resources (n=5), shared social responsibility (n=18), unprotected groups from female-only HPV vaccination (n=10), limited screening for HPV-associated noncervical cancers (n=6), consideration of ethical principles (n=17), and HPV vaccine mandates (n=5). Ethical and legal aspects must be considered when recommending vaccination for females only or GNV.

Risk Factors for Non-Human Papillomavirus (HPV) Type 16/18 Cervical Infections and Associated Lesions Among HPV DNA-Negative Women Vaccinated Against HPV-16/18 in the Costa Rica Vaccine Trial

BACKGROUND

Factors that lead human papillomavirus (HPV) infections to persist and progress to cancer are not fully understood. We evaluated co-factors for acquisition, persistence, and progression of non-HPV-16/18 infections among HPV-vaccinated women.

METHODS

We analyzed 2153 women aged 18-25 years randomized to the HPV-vaccine arm of the Costa Rica HPV Vaccine Trial. Women were HPV DNA negative for all types at baseline and followed for approximately 11 years. Generalized estimating equation methods were used to account for correlated observations. Time-dependent factors evaluated were age, sexual behavior, marital status, hormonally related factors, number of full-term pregnancies (FTPs), smoking behavior, and baseline body mass index.

RESULTS

A total of 1777 incident oncogenic non-HPV-16/18 infections were detected in 12 292 visits (average, 0.14 infections/visit). Age and sexual behavior-related variables were associated with oncogenic non-HPV-16/18 acquisition. Twenty-six percent of incident infections persisted for ≥1 year. None of the factors evaluated were statistically associated with persistence of oncogenic non-HPV-16/18 infections. Risk of progression to Cervical Intraepithelial Neoplasia grade 2 or worst (CIN2+) increased with increasing age (P for trend = .001), injectable contraceptive use (relative risk, 2.61 [95% confidence interval, 1.19-5.73] ever vs never), and increasing FTPs (P for trend = .034).

CONCLUSIONS

In a cohort of HPV-16/18-vaccinated women, age and sexual behavior variables are associated with acquisition of oncogenic non-HPV-16/18 infections; no notable factors are associated with persistence of acquired infections; and age, parity, and hormonally related exposures are associated with progression to CIN2+.

Population Impact of Girls-Only Human Papillomavirus 16/18 Vaccination in The Netherlands: Cross-Protective and Second-Order Herd Effects

Background

Human papillomavirus (HPV) vaccination programs achieve substantial population-level impact, with effects extending beyond protection of vaccinated individuals. We assessed trends in HPV prevalence up to 8 years postvaccination among men and women in the Netherlands, where bivalent HPV vaccination, targeting HPV types 16/18, has been offered to (pre)adolescent girls since 2009 with moderate vaccination coverage.

Methods

We used data from the PASSYON study, a survey initiated in 2009 (prevaccination) and repeated biennially among 16- to 24-year-old visitors of sexual health centers. We studied genital HPV positivity from 2009 to 2017 among women, heterosexual men, and unvaccinated women using Poisson generalized estimating equation models, adjusted for individual- and population-level confounders. Trends were studied for 25 HPV types detected by the SPF10-LiPA25 platform.

Results

A total of 6354 women (64.7% self-reported unvaccinated) and 2414 heterosexual men were included. Percentual declines in vaccine types HPV-16/18 were observed for all women (12.6% per year [95% confidence interval {CI}, 10.6–14.5]), heterosexual men (13.0% per year [95% CI, 8.3–17.5]), and unvaccinated women (5.4% per year [95% CI, 2.9–7.8]). We observed significant declines in HPV-31 (all women and heterosexual men), HPV-45 (all women), and in all high-risk HPV types pooled (all women and heterosexual men). Significant increases were observed for HPV-56 (all women) and HPV-52 (unvaccinated women).

Conclusions

Our results provide evidence for first-order herd effects among heterosexual men against HPV-16/18 and cross-protective types. Additionally, we show second-order herd effects against vaccine types among unvaccinated women. These results are promising regarding population-level and clinical impact of girls-only bivalent HPV vaccination in a country with moderate vaccine uptake.

Importance of human papillomavirus infection in squamous cell carcinomas of the tongue in Guangdong Province, China

Objective

Methods

Results

Conclusion

Buschke-Loewenstein Tumor: A Case Report and Advocacy for Human Papillomavirus Vaccination

Human papillomavirus (HPV) is a widespread sexually transmitted infection which can lead to genital warts, squamous cell carcinoma, and verrucous carcinomas. Buschke-Loewenstein tumor (BLT) is a verrucous carcinoma which occurs in the anogenital and perianal areas. BLT is often associated with HPV 6 and 11, but HPV is preventable through routine vaccination. The Centers for Disease Control and Prevention (CDC) provides recommendations for routine HPV vaccination among both adolescents and adults. Following these guidelines may result in decreased incidence of BLT and minimize the need for subsequent invasive treatment. Here we present a case of BLT and advocate the use of HPV vaccination among patients to prevent discussed potential adverse outcomes.

Prevalence of Oral HPV Infection in Unvaccinated Men and Women in the United States, 2009-2016

To estimate changes in oral human papillomavirus (HPV) prevalence attributable to vaccination vs herd immunity, this national survey study uses National Health and Nutrition Examination Survey data to compare oral HPV prevalence for 4 types targeted by HPV vaccine and 33 nonvaccine types in unvaccinated US adults aged 18 to 59 years from 2009 to 2016.

Vaccination of Young Women Decreases Human Papillomavirus Transmission in Heterosexual Couples: Findings from the HITCH Cohort Study

BACKGROUND

Vaccination against human papillomaviruses (HPV) prevents HPV infections and, consequently, cervical lesions. However, the effect of vaccination on HPV transmission within couples is unknown.

METHODS

We used data from HITCH, a prospective cohort study of heterosexual couples (women ages 18-24 years) in Montreal, 2005 to 2013. Vaccination history was self-reported. Genital samples were tested for HPV DNA by PCR (linear array). Type-specific viral loads were quantified using real-time PCR. OR and HR were estimated using multilevel mixed-effects logistic regression and a parametric model for interval- censored survival-time data, respectively. Differences in viral loads were evaluated using the Friedman ANOVA test.

RESULTS

Among 497 couples, 12, 16, and 35 women received 1, 2, or 3 vaccination doses at baseline, respectively. Median age at vaccination was 18 years. Most women (92.1%) had their first coitus before vaccination. At baseline, partner concordance of persistent HPV6/11/16/18 infections was lower in vaccinated than unvaccinated women [adjusted OR = 0.10; 95% confidence interval (CI), 0.01-0.65] but not for non α7/α9/α10-HPV types (adjusted OR = 1.00; 95% CI, 0.44-2.29). Incidence of persistent α7/α9/α10 HPV types in women was inversely associated with vaccination status at baseline (adjusted HR = 0.12; 95% CI, 0.03-0.47). Likewise, male partners of vaccinated women had a lower incidence of α7/α9/α10 HPV infections (adjusted OR = 0.22; 95% CI, 0.05-0.95). Vaccinated women with HPV 6/11/16/18 infections had lower viral loads (P = 0.001) relative to unvaccinated women.

CONCLUSIONS

Vaccination of sexually active women significantly reduced transmission of α7/α9/α10 HPV types in heterosexual couples.

IMPACT

These results underscore and quantify the positive effect of HPV vaccination on HPV transmission within heterosexual couples.

The Prevalence of HPV Genotypes in Iranian Population: An Update

Background & Objective:

Human papillomavirus (HPV) is the main cause of genital warts and some anogenital cancers in male and female subjects which is commonly transmitted by sexual contacts. The objective of this cross-sectional study was to examine the prevalence of HPV genotypes in 10,266 Iranian male and female population, according to their age.

Methods:

Samples were collected from the penile and anal sites of male subjects and the vagina and cervix of female subjects in a time period between 2011 and 2016. HPV DNA was detected in PCR using the MY09 and MY11 primers, and the INNO-LiPA assay was applied for HPV genotyping. To investigate the relevance of HPV infection and age, the samples were classified into 4 age groups (13-29, 30-44, 45-59, and 60-74).

Results:

Totally, the most common low risk HPV genotypes detected in the studied male and female subjects were HPV-6 (77.7% and 43.3%) and HPV-11 (13.7% and 11.4%), and more frequent high risk HPV genotypes were HPV-16 (5.5% and 16.6%) and HPV-52 (3.2% and 9.6%), respectively. High burden of the HPV infection was observed at ranges of 30 and 44 years (51.8%) with a peak at ranges between 30 and 32 years. No considerable statistically significant correlation was found between HPV infection and age (P=1).

Conclusion:

This study gave an epidemiological overview of circulating HPV genotypes in Iranian population to develop future vaccination policies, though the findings of prevalent HPV genotypes in female subjects were inconsistent with the previous studies reported in Iran.

[The health economics of cancer screening in Germany: Which population-based interventions are cost-effective?]

Only a small proportion of German health expenditure is spent on prevention and early detection (screening). The rationale for screening is to identify persons with disease precursors or at the early stage of diseases when they are still asymptomatic, in order to decrease disease-specific morbidity and mortality. In Germany, the economic evidence is one of the evaluation criteria for screening measures, which, among other things, takes into account the additional cost per additional case detected or per case-related event avoided, as well as a cost-benefit balance.For this purpose, cost-effectiveness analyses, which report marginal or incremental cost effectiveness ratios, comparing a measure with its appropriate alternatives, may be a useful tool. Their application requires a defensible benchmark (threshold) for cost effectiveness and a supplementary analysis of the necessary infrastructure and the budgetary impact associated with program implementation. Also (albeit not only) because of the usually long time required to observe the clinical outcomes of a screening measure, the economic evaluation of such programs regularly involves the application of decision analytic simulation models. With regard to cancer screening programs, the available models indicate an excellent cost-benefit ratio for the fecal occult blood test and colonoscopy for colorectal cancer screening and, similarly, for the use of mammography for breast cancer screening. On the other hand, the economic evidence in favor of low-dose computed tomography for lung cancer screening does not yet appear sufficiently strong, and the currently available health economic evidence does not support the use of PSA testing for prostate screening.

Human Papillomavirus Vaccine Effectiveness and Herd Protection in Young Women

BACKGROUND

Clinical trials of the 4-valent human papillomavirus (HPV) vaccine demonstrate high efficacy, but surveillance studies are essential to examine the long-term impact of vaccine introduction on HPV prevalence in community settings. The aims of this study were to determine during the 11 years after vaccine introduction the prevalence of (1) vaccine-type HPV in adolescent and young adult women who were vaccinated (to assess vaccine effectiveness) and (2) vaccine-type HPV in women who were unvaccinated (to assess herd protection).

METHODS

Young women 13 to 26 years of age were recruited from hospital-based and community health clinics for 4 surveillance studies from 2006 to 2017. We determined the proportion of vaccinated and unvaccinated women who were positive for vaccine-type HPV across the studies, and the odds of positivity for vaccine-type HPV using logistic regression; all analyses were propensity score-adjusted to control for between-wave differences in participant characteristics.

RESULTS

Vaccination rates increased from 0% to 84.3% (97% of study participants received the 4-valent vaccine). Among women who were vaccinated, 4-valent vaccine-type HPV detection decreased from 35% to 6.7% (80.9% decline; odds ratio 0.13, 95% confidence interval 0.08 to 0.22). Among women who were unvaccinated, 4-valent vaccine-type HPV detection decreased from 32.4% to 19.4% (40% decline; odds ratio 0.50, 95% confidence interval 0.26 to 0.97). Estimated vaccine effectiveness was 90.6% in wave 3 and 80.1% in wave 4.

CONCLUSIONS

In this study in which trends in HPV in a US community >10 years after 4-valent HPV vaccine introduction and after 9-valent vaccine introduction were examined, we found evidence of vaccine effectiveness and herd protection. Further research is needed to examine trends in 9-valent vaccine-type HPV after higher rates of vaccination are achieved.