Epidemiology of Any and Vaccine-Type Anogenital Human Papillomavirus Among 13-26-Year-Old Young Men After HPV Vaccine Introduction

Application of the theoretical domains framework to identify factors influencing catch-up HPV vaccinations among male college students in the United States: A review of evidence and recommendations

BACKGROUND

Genital human papillomavirus (HPV) infection is the most prevalent sexually transmitted infection among young adults ages 15-25 years in the United States (US). Although HPV vaccines are recommended for individuals ages through 26 years, vaccine completion rates remain substantially low.

METHODS

Accordingly, our study utilized a comprehensive - Theoretical Domains Framework (TDF) of behavior change to systematically identify facilitators and barriers to catch-up HPV vaccinations. Five databases - Medline, Embase, CINAHL, ERIC, and PsycINFO were searched from January 2009 to July 2019 for empirical studies using quantitative and qualitative methods to assess HPV vaccine uptake among males ages 18-26 years within US college and university settings. The TDF analytic process included a content analysis using the mixed deductive-inductive approach to extract, analyze and categorize data into TDF domains/themes and sub-themes.

RESULTS

Overall, 17 studies were selected for data extraction. We identified eleven key TDF domains that influenced HPV vaccination behavior among college male students: 'knowledge' (82% of included studies), 'environmental context and resources' (53%), 'beliefs about consequences' (53%), 'unrealistic optimism' (50%) and 'pessimism' (6%), 'emotion' (50%), 'social influences' (50%), 'beliefs about capabilities' (41%), 'intention' (24%), 'reinforcement' (18%), 'social professional role and identity'(12%), and 'behavioral regulation' (12%). Barriers influencing HPV vaccine uptake included lack of knowledge and awareness regarding HPV infections, HPV vaccine safety, effectiveness, side effects, and costs; absence of health providers' recommendations; lack of healthcare and health insurance; low levels of perceived susceptibility and severity for HPV infections; HPV vaccine misinformation; as well as social stigma and peer influences regarding HPV vaccinations. Enablers for HPV vaccine uptake included high levels of perceived benefits for HPV vaccines.

DISCUSSION

Our study theoretically identified factors influencing HPV vaccinations. This could inform the efficient planning, support, and implementation of interventions that facilitate catch-up HPV vaccination practices among high-risk males within college/university settings.

Vacuna del virus del papiloma humano: valoración bioética de la discriminación por sexo

La infección por el virus del papiloma humano (VPH) constituye la causa necesaria, aunque no suficiente, de la enfermedad de transmisión sexual más frecuente en el mundo, responsable del 4,5 % de todos los cánceres en ambos sexos. La vacunación frente al VPH, con niveles de eficacia y seguridad similares en ambos sexos, está dirigida básicamente a mujeres, para reducir la incidencia de infección y sus consecuencias, como el cáncer de cérvix. La transmisibilidad del virus en ambos sexos y la inmunidad colectiva que proporciona la vacunación universal hace que su extensión al sexo masculino constituya una cuestión no solo de salud pública, sino también un dilema bioético relacionado con la protección de la salud y la equitativa distribución de los recursos. Este trabajo aborda el análisis bioético de la extensión de la vacunación contra VPH a ambos sexos.

Real-world impact and effectiveness of the quadrivalent HPV vaccine: an updated systematic literature review

INTRODUCTION

Human papillomavirus (HPV) infection, which poses significant disease burden, is decreasing following implementation of vaccination programs. Synthesized evidence on HPV vaccine real-world benefit was published in 2016. However, long-term impact of vaccination, and how vaccination programs influence infection rates and disease outcomes, requires further examination.

AREAS COVERED

We systematically reviewed observational studies on HPV vaccination within MEDLINE, EMBASE, and Google Scholar from 2016 to 2020, involving 14 years of follow-up data. We identified 138 peer-reviewed publications reporting HPV vaccine impact or effectiveness. Outcomes of interest included rates of infection at different anatomical sites and incidence of several HPV-related disease endpoints.

EXPERT OPINION

The expansion of HPV vaccination programs worldwide has led to a reduction in genital infection and significant decreases in incidence of HPV-related disease outcomes. Therefore, the WHO has set goals for the elimination of cervical cancer as a public health concern. To track progress toward this requires an understanding of the effectiveness of different vaccination initiatives. However, the impact on males, and potential benefit of gender-neutral vaccination programs have not been fully explored. To present an accurate commentary on the current outlook of vaccination and to help shape policy therefore requires a systematic review of available data.

Human papillomavirus vaccine effectiveness by number of doses: Updated systematic review of data from national immunization programs

BACKGROUND

Human papillomavirus (HPV) vaccines were first licensed as a three-dose series. Two doses are now widely recommended in some age groups; there are data suggesting high efficacy with one dose. We updated a systematic literature review of HPV vaccine effectiveness by number of doses in observational studies.

METHODS

We searched Medline and Embase databases from January 1, 2007, through September 29, 2021. Data were extracted and summarized in a narrative synthesis. We also conducted quality assessments for bias due to selection, information, and confounding.

RESULTS

Overall, 35 studies were included; all except one were conducted within the context of a recommended three-dose schedule. Evaluations were in countries that used bivalent HPV vaccine (seven), quadrivalent HPV vaccine (27) or both (one). Nine evaluated effectiveness against HPV infection, ten anogenital warts, and 16 cervical abnormalities. All studies were judged to have moderate or serious risk of bias. The biases rated as serious would likely result in lower effectiveness with fewer doses. Investigators attempted to control for or stratify by potentially important variables, such as age at vaccination. Eight studies evaluated impact of buffer periods (lag time) for case counting and 10 evaluated different intervals between doses for two-dose vaccine recipients. Studies that stratified by vaccination age found higher effectiveness with younger age at vaccination, although differences were not all formally tested. Most studies found highest estimates of effectiveness with three doses; significant effectiveness was found among 28/29 studies that evaluated three doses, 19/29 that evaluated two doses, and 18/30 that evaluated one dose. Some studies that adjusted or stratified analyses by age at vaccination found similar effectiveness with three, two and one doses.

CONCLUSION

Observational studies of HPV vaccine effectiveness have many biases. Studies examining persons vaccinated prior to sexual activity and using methods to reduce sources of bias are needed for valid effectiveness estimates.

Effectiveness of Human Papillomavirus (HPV) Vaccination Against Penile HPV Infection in Men Who Have Sex With Men and Transgender Women

BACKGROUND

In the United States, human papillomavirus (HPV) vaccination has been recommended since 2011 for boys aged 11-12 years, with catch-up vaccination recommended through age 26 years for previously unvaccinated men who have sex with men (MSM).

METHODS

During 2016-2018, a cross-sectional study enrolled MSM and transgender women aged 18-26 years in Seattle, Washington. Participants submitted self-collected penile swab specimens for HPV genotyping. HPV vaccination history was self-reported. We compared HPV prevalence among vaccinated participants with that in participants with no or unknown vaccination history, using log-binomial regression to estimate adjusted prevalence ratios and confidence intervals.

RESULTS

Among 687 participants, 348 (50.7%) self-reported ever receiving ≥1 HPV vaccine dose; the median age at first HPV vaccination was 21 years, and the median age at first sex, 17 years. Overall, the prevalence of penile quadrivalent HPV vaccine (4vHPV)-type HPV was similar in vaccinated participants (12.1%) and participants with no or unknown vaccination (15.6%) (adjusted prevalence ratio, 0.69 [95% confidence interval, .47-1.01]). However, the prevalence was significantly lower in participants vaccinated at age ≤18 years than in those with no of unknown vaccination (0.15 [.04-.62]), corresponding to a vaccine effectiveness of 85% against 4vHPV-type HPV.

CONCLUSIONS

Results suggest that HPV vaccination is effective in preventing penile HPV infections in young MSM when administered at age ≤18 years.

Real-world impact and effectiveness assessment of the quadrivalent HPV vaccine: a systematic review of study designs and data sources

INTRODUCTION

Vaccine effectiveness and impact studies are typically observational, generating evidence after vaccine launch in a real-world setting. For human papillomavirus (HPV) vaccination studies, the variety of data sources and methods used is pronounced. Careful selection of study design, data capture and analytical methods can mitigate potential bias in such studies.

AREAS COVERED

We systematically reviewed the different study designs, methods, and data sources in published evidence (1/2007-3/2020), which assessed the quadrivalent HPV vaccine effectiveness and impact on cervical/cervicovaginal, anal, and oral HPV infections, anogenital warts, lesions in anus, cervix, oropharynx, penis, vagina or vulva, and recurrent respiratory papillomatosis.

EXPERT OPINION

The rapid growth in access to real-world data allows global monitoring of effects of different public health interventions, including HPV vaccination programs. But the use of data which are not collected or organized to support research also underscore a need to develop robust methodology that provides insight of vaccine effects and consequences of different health policy decisions. To achieve the WHO elimination goal, we foresee a growing need to evaluate HPV vaccination programs globally. A critical appraisal summary of methodology used will provide timely guidance to researchers who want to initiate research activities in various settings.

Vaccine Effectiveness Against Prevalent Anal and Oral Human Papillomavirus Infection Among Men Who Have Sex With Men-United States, 2016-2018

BACKGROUND

In the United States, human papillomavirus (HPV) vaccination has been recommended for young adult men who have sex with men (MSM) since 2011.

METHODS

The Vaccine Impact in Men study surveyed MSM and transgender women aged 18-26 years in 3 US cities during 2016-2018. Self-collected anal swab and oral rinse specimens were assessed for 37 types of HPV. We compared HPV prevalence among vaccinated and unvaccinated participants and determined adjusted prevalence ratios (aPR) and 95% confidence intervals (CI).

RESULTS

Among 1767 participants, 704 (39.8%) self-reported receiving HPV vaccine. Median age at vaccination (18.7 years) was older than age at first sex (15.7 years). Quadrivalent vaccine-type HPV was detected in anal or oral specimens from 475 (26.9%) participants. Vaccine-type HPV prevalence was lower among vaccinated (22.9%) compared with unvaccinated (31.6%) participants; aPR for those who initiated vaccination at age ≤18 years was 0.41 (CI, 0.24-0.57) and at age >18 years was 0.82 (CI, 0.67-0.98). Vaccine effectiveness of at least 1 HPV vaccine dose at age ≤18 years or >18 years was 59% and 18%, respectively.

CONCLUSIONS

Findings suggest real-world effectiveness of HPV vaccination among young adult MSM. This effect was stronger with younger age at vaccination.

Sexual Network Patterns and Their Association With Genital and Anal Human Papillomavirus Infection in Adolescent and Young Men

PURPOSE

This study aimed to determine individual- and partner-level factors associated with human papillomavirus (HPV) infection in vaccinated and unvaccinated men.

METHODS

A total of 747 men, aged 13-26 years, completed a survey of sexual behaviors and were tested for genital and perianal/anal HPV (36 types). Sexual network variables included recent and lifetime concurrency (being in more than one sexual relationship at the same time) and recent sex partner discordance (by race, ethnicity, age, and number of sexual partners). We determined individual-level and sexual network variables associated with ≥1 HPV type and HPV16/18, stratified by vaccination status, using separate multivariable logistic regression models.

RESULTS

Participants' mean age was 21.2 years; 64% were positive for ≥1 HPV type and 21% for HPV16/18. Factors associated with ≥1 HPV type in unvaccinated men included recruitment site and lifetime concurrency. Factors associated with ≥1 HPV type among vaccinated men included recruitment site, Chlamydia history, main male partner, number of lifetime female partners, and no condom use with female partner. Factors associated with HPV16/18 in unvaccinated men included race and partner concurrency. Factors associated with HPV16/18 in vaccinated men included ethnicity, main male partner, and recent concurrency.

CONCLUSIONS

Sexual network variables associated with HPV infection were different based on vaccination status and HPV type, suggesting risk factors for HPV infection may change as the proportion of vaccinated men increases. In addition, participant report of concurrency and not knowing whether one had practiced concurrency were consistent risk factors; clinicians should consider including concurrency in the sexual history to determine the risk of HPV.

Decline in vaccine-type human papillomavirus prevalence in young men from a Midwest metropolitan area of the United States over the six years after vaccine introduction

PURPOSE

The aim of this study was to determine changes in human papillomavirus (HPV) prevalence among young men from a Midwest metropolitan area over the six years after vaccine introduction, including HPV prevalence in men overall, in vaccinated men to examine vaccine impact and in unvaccinated men to examine herd protection. An exploratory aim was to examine associations between number of vaccine doses and HPV prevalence.

METHODS

Men aged 14-26 years reporting male-female and/or male-male sexual contact were recruited from a primary care clinic, sexually transmitted disease clinic, and community setting during two waves of data collection: 2013-2014 (N = 400) and 2016-2017 (N = 347). Participants completed a questionnaire and were tested for penile, scrotal and anal HPV. Changes in prevalence of any (≥1 type) and vaccine-type HPV (HPV6, 11, 16, and/or 18) were examined using propensity score weighted logistic regression. Associations between number of doses and HPV infection were determined using chi-square tests and logistic regression.

RESULTS

The proportion of men with a history of ≥1 HPV vaccine doses increased from 23% to 44% (p < 0.001) from waves 1 to 2. After propensity score weighting, infection with ≥1 vaccine-type HPV significantly decreased among all men (29% to 20%; 31% decrease; odds ratio [OR] = 0.62, 95% confidence interval [CI] = 0.44-0.88) and unvaccinated men (32% to 21%; 36% decrease; OR = 0.56, 95%CI = 0.34-0.86); there was a non-significant decrease (21%) among vaccinated men. Associations between number of doses and HPV prevalence were not statistically significant.

CONCLUSIONS

Prevalence of vaccine-type HPV decreased among all, vaccinated, and unvaccinated men six years after HPV vaccine recommendation, supporting vaccine impact and herd protection. Decreases in vaccine-type HPV in all men appear to be due to decreases in unvaccinated men, suggesting that the full impact of vaccination has yet to be realized. Continued monitoring and efforts to vaccinate men prior to sexual initiation are warranted.