Population-Level Herd Protection of Males From a Female Human Papillomavirus Vaccination Program: Evidence from Australian Serosurveillance

Prevalence of Human Papillomavirus (HPV) and HPV Type Distribution in Penile Samples in Young Men in Denmark: Results 10 Years After Implementation of a Girls-Only HPV Vaccination Program

BACKGROUND

In Denmark, a girls-only human papillomavirus (HPV) vaccination program was initiated in 2008-2009. The study aim was to assess the HPV prevalence and type distribution in younger men prior to HPV vaccination in men.

METHODS

The study population was younger men who attended information days regarding military service. At random days (2019-2020), 280 men were included. We collected questionnaire data regarding risk factors for HPV infection and a penile swab for HPV testing. We compared results in this study with those from a previous study of young men (2006-2007).

RESULTS

The majority of participants (94%) were 18-20 years old. The median number of lifetime sexual partners was 4. Altogether, 130 men (46.4%) were HPV positive. No infections with HPV types 6, 11, 16, 18, 31, and 45 were detected. The most frequent type was HPV-51 (detected in 11.1%). Comparison showed that the odds of high-risk HPV type infection were higher in 2019-2020 (prevalence odds ratio [POR], 1.7 [95% confidence interval {CI}, 1.1-2.7]) compared with 2006-2007. In contrast, the odds were lower (POR, 0.3 [95% CI, .1-.6]) for HPV types targeted by the 9-valent HPV vaccine.

CONCLUSIONS

The multicohort girls-only vaccination program has to a large degree protected young men against the HPV types included in the licensed vaccines. This does not speak against gender-neutral vaccination as the HPV prevalence is still high, although consisting largely of less carcinogenic HPV types.

Public health opportunities resulting from sufficient HPV vaccine supply and a single-dose vaccination schedule

Many countries with the highest burdens of cervical cancer have not yet offered human papillomavirus (HPV) vaccines to most of their age-eligible girls, who as adults also have limited or no access to effective cervical cancer screening or treatment. There are now 2 complementary developments that could make HPV vaccines more accessible and affordable: 1) the current and projected increases in HPV vaccine supply; and 2) the permissive recommendation for single-dose HPV vaccination schedules. This change in policy paired with the healthier HPV vaccine supply is an incredible opportunity to facilitate rapid access and expansion of HPV vaccination. Female adolescent vaccination including multiage cohorts must be prioritized. In the coming decades, this is the most cost-effective approach to avert millions of projected cervical cancer cases, which account for most HPV-related cancers globally.

Human papillomavirus seroprevalence in pregnant women following gender-neutral and girls-only vaccination programs in Finland: A cross-sectional cohort analysis following a cluster randomized trial

BACKGROUND

Cervical cancer elimination through human papillomavirus (HPV) vaccination programs requires the attainment of herd effect. Due to its uniquely high basic reproduction number, the vaccination coverage required to achieve herd effect against HPV type 16 exceeds what is attainable in most populations. We have compared how gender-neutral and girls-only vaccination strategies create herd effect against HPV16 under moderate vaccination coverage achieved in a population-based, community-randomized trial.

METHODS AND FINDINGS

In 2007-2010, the 1992-1995 birth cohorts of 33 Finnish communities were randomized to receive gender-neutral HPV vaccination (Arm A), girls-only HPV vaccination (Arm B), or no HPV vaccination (Arm C) (11 communities per trial arm). HPV16/18/31/33/35/45 seroprevalence differences between the pre-vaccination era (2005-2010) and post-vaccination era (2011-2016) were compared between all 8,022 unvaccinated women <23 years old and resident in the 33 communities during 2005-2016 (2,657, 2,691, and 2,674 in Arms A, B, and C, respectively). Post- versus pre-vaccination-era HPV seroprevalence ratios (PRs) were compared by arm. Possible outcome misclassification was quantified via probabilistic bias analysis. An HPV16 and HPV18 seroprevalence reduction was observed post-vaccination in the gender-neutral vaccination arm in the entire study population (PR16 = 0.64, 95% CI 0.10-0.85; PR18 = 0.72, 95% CI 0.22-0.96) and for HPV16 also in the herpes simplex virus type 2 seropositive core group (PR16 = 0.64, 95% CI 0.50-0.81). Observed reductions in HPV31/33/35/45 seroprevalence (PR31/33/35/45 = 0.88, 95% CI 0.81-0.97) were replicated in Arm C (PR31/33/35/45 = 0.79, 95% CI 0.69-0.90).

CONCLUSIONS

In this study we only observed herd effect against HPV16/18 after gender-neutral vaccination with moderate vaccination coverage. With only moderate vaccination coverage, a gender-neutral vaccination strategy can facilitate the control of even HPV16. Our findings may have limited transportability to other vaccination coverage levels.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT00534638, https://clinicaltrials.gov/ct2/show/NCT00534638.

Changes in HPV Seroprevalence from an Unvaccinated toward a Girls-Only Vaccinated Population in the Netherlands

BACKGROUND

In the Netherlands, bivalent human papillomavirus (HPV) vaccination was included in the National Immunization Program for 12-year-old girls in 2010 (vaccination coverage, 45%-60%). We examined possible changes in HPV seroprevalence in the HPV-unvaccinated Dutch population aged 0-89 years, comparing prevaccination data with data of approximately 6 years after implementation of national vaccination.

METHODS

Serum samples of men and women were used from two cross-sectional population-based serosurveillance studies performed before (2006-07, n = 6,384) and after (2016-17, n = 5,645) implementation of HPV vaccination in the Netherlands. Seven high-risk HPV-specific antibodies (HPV16, 18, 31, 33, 45, 52, and 58) were tested in a virus-like particle-based multiplex immunoassay.

RESULTS

Type-specific HPV seroprevalence increased in women between 2006-07 and 2016-17. Also, a higher seroprevalence for at least one type in women >15 years was found in 2016-17 (31.7%) compared with 2006-07 (25.2%). In men, overall HPV seroprevalence remained similar; however, a lower seroprevalence was found for HPV16 in 2016-17 (7.5%) compared with 2006-07 (10.6%).

CONCLUSIONS

Our results indicate an increase in high-risk HPV types in women and a rather stable exposure in men. No clear effects of the strategy of girls-only vaccination were observed in men, probably because of the short time after introduction combined with suboptimal coverage.

IMPACT

No herd immunity has been observed yet in a population with suboptimal HPV vaccination coverage.

Geographical disparities in human papillomavirus herd protection

BACKGROUND

Human papillomavirus (HPV) vaccination has occurred unequally across the United States, potentially contributing to uneven vaccine-type HPV prevalence between regions. We examined whether emerging vaccine-related herd protection exhibits regional differences among unvaccinated girls and women.

METHODS

We evaluated the prevalence of vaginal HPV among women 14-59 years of age from 2003 to 2014 using repeated cross-sectional data from the National Health and Nutrition Examination Survey (NHANES). Women who provided an adequate vaginal swab sample were included. Vaginal prevalence of vaccine-type HPV (types 6, 11, 16, 18) were examined in four regions of the United States between 2003 and 2014. We examined vaccine-type HPV prevalence in 2007-2014 in each US census region among younger participants (14-34 years old) stratified by vaccination status to determine whether one or both groups contributed to uneven HPV prevalence.

RESULTS

A total of 12 175 participants 14-59 years of age met inclusion criteria. Vaccine-type HPV prevalence decreased in all regions. Vaccine-type HPV varied by region only among unvaccinated 14-34 year olds, with a higher prevalence in the Midwest (13.8%, 95% confidence interval (CI): 10.7-17.0) and South (12.5%, 95% CI: 10.2-14.8) compared to the Northeast (8.9%, 95% CI: 6.5-11.2). No regional variation in vaccine-type HPV prevalence was observed among vaccinated participants.

CONCLUSIONS

Higher prevalence of vaccine-type HPV among unvaccinated women in the South and Midwest may contribute to regional disparities in HPV-related cancer incidence, as emerging herd immunity may not be as strong in those regions.

Men having sex with men and the HPV vaccine in France: A low vaccine coverage that may be due to its infrequent proposal by physicians

INTRODUCTION

In France, the human papilloma (HPV) vaccine is recommended to all female adolescents, and since 2016 to men having sex with men (MSM) under the age of 27. Here, we aimed to explore HPV vaccine coverage in adult MSM living in France.

METHODS

We elaborated an anonymous online questionnaire targeting MSM and disseminated it between October 7, 2018 and January 15, 2019 by various means, including a Facebook® discussion forum for pre-exposure prophylaxis (PrEP) users.

RESULTS

Overall, 2094 participants completed the questionnaire (mean age 35.4 ± 11 years); 25.8% were in the age class targeted by the HPV vaccine recommendation; 16.1% were in a PrEP program. On a 1-10 scale, they evaluated being "in favor of vaccination" at a median of 10, and general vaccine usefulness and harmfulness at medians of 10 and 2, respectively; 62.4% considered that the HPV vaccine was rather not or not at all dangerous. Those using PrEP had better perceptions of vaccination in general and of the HPV vaccine in particular. For the 1728 participants with a family physician, he/she had proposed the HPV vaccine in 9.9% of cases (9.1% of those in the targeted age class [<27 years]). Overall, 1994 knew their HPV vaccine status; 8.0% had received at least 1 dose of the vaccine, including 17.9% of those in the targeted age class (and 52.2% among the 40 participants in this age group who received PrEP). When the 1935 participants who declared to be unvaccinated against HPV were asked whether they would accept to be vaccinated, 34.4% answered "rather yes" and 45.5% "definitely yes".

CONCLUSION

HPV vaccine coverage is low among French MSM. Our results suggest that this trend has more to do with the infrequent proposals made by clinicians than with negative vaccine perceptions.

The impact of 10 years of human papillomavirus (HPV) vaccination in Australia: what additional disease burden will a nonavalent vaccine prevent?

Background: A National human papilloma virus (HPV) Vaccination Programme for the prevention of HPV infection and associated disease using the quadrivalent HPV vaccine (4vHPV) has been funded and implemented in Australia since 2007, initially for girls only and extended to boys in 2013, with uptake rates among the highest observed worldwide. Aim: We report on the impact of this national programme on HPV prevalence and associated disease burden and estimate the potential impact of adopting a nonavalent HPV (9vHPV) vaccine. Methods: We performed a non-systematic literature review of studies measuring the burden of HPV-associated disease and infection in Australia before and after introduction of HPV vaccination. We also included key national reports with estimates of HPV-related disease burden. Results: Substantial declines in high-grade cervical disease and genital warts among vaccine-eligible women have been observed. Reductions in genital warts incidence and HPV prevalence among heterosexual men of similar age were observed before introduction of the male vaccination programme, indicating a substantial herd effect. 9vHPV vaccine is expected to prevent up to 90% of cervical and 96% of anal cancers. Of an estimated 1,544 HPV-associated cancers in 2012, 1,242 would have been preventable by the 4vHPV vaccine and an additional 187 anogenital cancers by the 9vHPV vaccine. Conclusions: Vaccination using 4vHPV vaccine has had a large demonstrable impact on HPV-related disease in Australia. A switch to 9vHPV could further reduce the HPV-associated cancer burden. With continued high coverage among both males and females, elimination of vaccine-type HPV disease seems achievable in Australia.

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

INTRODUCTION

Vaccine herd effects are the indirect protection that vaccinated persons provide to those who remain susceptible to infection, due to the reduced transmission of infections. Herd effects have been an important part of the discourse on how to best implement human papillomavirus (HPV) vaccines and prevent HPV-related diseases.

AREAS COVERED

In this paper, we review the theory of HPV vaccine herd effects derived from mathematical models, give an account of observed HPV vaccine herd effects worldwide, and examine the implications of vaccine herd effects for future cervical cancer screening efforts.

EXPERT COMMENTARY

HPV vaccine herd effects improve the cost-effectiveness of vaccinating preadolescent girls, but contribute to making gender-neutral vaccination less economically efficient. Vaccination coverage and sexual mixing patterns by age are strong determinants of herd effects. Many countries worldwide are starting to observe reductions in HPV-related outcomes likely attributable to herd effects, most notably declining anogenital warts in young men, and declining HPV-16/18 infection prevalence in young unvaccinated women. Policy makers making recommendations for cervical cancer screening will have to consider HPV vaccination coverage and herd effects, as these will affect the positive predictive value of screening and the risk of cervical cancer in unvaccinated women.

Population-based HPV vaccination programmes are safe and effective: 2017 update and the impetus for achieving better global coverage

Persistent oncogenic human papillomavirus (HPV) is the cause of cervical cancer, as well as cancers of the anus, penis, vulva, vagina and oropharynx. There is good evidence that prophylactic HPV vaccines are immunogenic and effective against targeted-type HPV infections and type-specific genital lesions, including high-grade cervical intraepithelial neoplasia (CIN), when administered prior to HPV infection. There is good evidence that HPV vaccines are safe in population usage, with the most frequent adverse event being injection-site reactions. There is evidence to support some cross-protection against non-targeted types occurring following the administration of HPV vaccines. There is limited evidence suggesting that HPV vaccines may be beneficial in preventing future disease in women treated for high-grade CIN. This chapter focuses on the accumulated evidence regarding the global use of the three licensed HPV vaccines including safety, immunogenicity, duration of protection, effectiveness, coverage to date and barriers to higher coverage.