Impact of a Gender-Neutral HPV Vaccination Program in Men Who Have Sex with Men (MSM)

Inclusion of marginalized populations in HPV vaccine modeling: A systematic review

OBJECTIVE

Models simulating the potential impacts of Human Papillomavirus (HPV) vaccine have been used globally to guide vaccination policies and programs. We sought to understand how and why marginalized populations have been incorporated into HPV vaccine simulation models.

METHODS

We conducted a systematic search of PubMed, CINAHL, Scopus, and Embase to identify studies using simulation models of HPV vaccination incorporating one or more marginalized population through stratification or subgroup analysis. We extracted data on study characteristics and described these overall and by included marginalized groups.

RESULTS

We identified 36 studies that met inclusion criteria, which modeled vaccination in 21 countries. Models included men who have sex with men (MSM; k = 16), stratification by HIV status (k = 9), race/ethnicity (k = 6), poverty (k = 5), rurality (k = 4), and female sex workers (k = 1). When evaluating for a marginalized group (k = 10), HPV vaccination was generally found to be cost-effective, including for MSM, individuals living with HIV, and rural populations. In studies evaluating equity in cancer prevention (k = 9), HPV vaccination generally advanced equity, but this was sensitive to differences in HPV vaccine uptake and use of absolute or relative measures of inequities. Only one study assessed the impact of an intervention promoting HPV vaccine uptake.

DISCUSSION

Incorporating marginalized populations into decision models can provide valuable insights to guide decision making and improve equity in cancer prevention. More research is needed to understand the equity impact of HPV vaccination on cancer outcomes among marginalized groups. Research should emphasize implementation - including identifying and evaluating specific interventions to increase HPV vaccine uptake.

Barriers and facilitators of HPV vaccination in sub-saharan Africa: a systematic review

BACKGROUND

Human Papilloma Virus (HPV) is the most common sexually transmitted infection worldwide. Globally, both men and women have a 50% risk of being infected at least once in their life. HPV prevalence is among the highest in sub-Saharan Africa (SSA), at an average of 24%. HPV causes different types of cancers, including cervical cancer (CC), which is the leading cause of cancer deaths among women in SSA. HPV-vaccination has been proven to be effective in reducing HPV induced cancers. SSA countries are delayed in reaching the WHO's target of fully vaccinating 90% of girls within the age of 15 by 2030. Our systematic review aims to identify barriers and facilitators of HPV-vaccination in SSA to inform national implementation strategies in the region.

METHODS

This is a mixed method systematic review based on the PRISMA statement and The Joanna Briggs Institute Reviewers' Manual. Search strategies were adapted to each selected database: PubMed/MEDLINE, Livivo, Google Scholar, Science Direct, and African Journals Online for papers published in English, Italian, German, French and Spanish between 1 December 2011 and 31 December 2021. Zotero and Rayyan were the software used for data management. The appraisal was conducted by three independent reviewers.

RESULTS

A total of 20 articles were selected for appraisal from an initial 536 articles. Barriers included: limited health system capacities, socio-economic status, stigma, fear and costs of vaccines, negative experience with vaccinations, COVID-19 pandemic, lack of correct information, health education (HE) and consent. Additionally, we found that boys are scarcely considered for HPV-vaccination by parents and stakeholders. Facilitators included: information and knowledge, policy implementation, positive experience with vaccinations, HE, stakeholders' engagement, women's empowerment, community engagement, seasonality, and target-oriented vaccination campaigns.

CONCLUSIONS

This review synthesizes barriers and facilitators of HPV-vaccinations in SSA. Addressing these can contribute to the implementation of more effective HPV immunization programs targeted at eliminating CC in line with the WHO 90/70/90 strategy.

REGISTRATION AND FUNDING

Protocol ID: CRD42022338609 registered in the International Prospective Register of Systematic Reviews (PROSPERO). Partial funds: German Centre for Infection research (DZIF) project NAMASTE: 8,008,803,819.

Factors influencing HPV vaccination willingness among men who have sex with men in China: a structural equation modeling analysis

Men who have sex with men (MSM) are at high risk of infection with human papillomavirus (HPV). Some countries have incorporated MSM into their HPV vaccination strategies. The acceptance of the HPV vaccine is an important factor affecting vaccine promotion in MSM. This study aims to analyze the factors influencing HPV vaccination willingness among MSM in China. Non-probability sampling was used to recruit MSM in China in June 2021. The information collected included demographic characteristics, HPV knowledge, attitude, behavior, history of sexually transmitted diseases (STDs), and HPV vaccination intention. A structural equation model was used to analyze the data based on the theory of knowledge-attitude-behavior. Among 889 participants, 736 (82.79%) of the MSM were willing to receive the HPV vaccine. The results of the structural equation model showed that knowledge, attitude, behavior, and STD history influenced the vaccination intention, of which knowledge (total effect of .36) and attitude (total effect of .31) had the greatest influence. Since most MSM in China were willing to be vaccinated against HPV, they should be considered for inclusion in the HPV vaccination program. Enhancing HPV awareness and improving risk awareness may be useful in increasing the vaccination willingness of MSM in China.

Factors Related to HPV Vaccination Intention among MSM in China: A Bayesian Network Model

(1) Background: Men who have sex with men (MSM) are at high risk of human papillomavirus (HPV) infection, and HPV vaccination is the best strategy to prevent HPV infection. Accepting HPV vaccination is an essential factor affecting vaccine promotion among MSM. We aimed to explore the factors related to HPV vaccination intention among MSM and analyze the potential relationship between these factors. (2) Methods: We adopted a nonprobability sampling method to recruit MSM volunteers. Information collection included general demographics, personal behavioral characteristics, knowledge of HPV/vaccine attitudes, and risk threat perception. Bayesian networks (BNs) were used to analyze the data statistically. (3) Results: The BNs showed that perceived HPV risk and attitudes toward vaccine promotion were directly correlated factors, whereas knowledge of HPV/vaccines, a history of HIV testing, and the number of male sexual partners in the past 6 months were indirectly correlated factors. (4) Conclusions: The results of this study illustrate that MSM have a relatively high propensity to receive HPV vaccines. The proposal that strengthening the propagation of HPV and its relevant vaccines, encouraging MSM to undergo regular corresponding tests, and improving their risk perception of HPV infection can be raised to promote HPV vaccination among MSM.

Update on the Epidemiological Features and Clinical Implications of Human Papillomavirus Infection (HPV) and Human Immunodeficiency Virus (HIV) Coinfection

Human papillomavirus (HPV) infection is the most common sexually transmitted infection (STI) worldwide. Although most HPV infections will spontaneously resolve, a considerable proportion of them will persist, increasing the risk of anogenital dysplasia, especially within certain populations, such as patients infected with human immunodeficiency virus (HIV). Furthermore, high-risk oncogenic HPV types (HR-HPV) are the main cause of cervix and other anogenital cancers, such as cancer of the vagina, vulva, penis, or anus. HIV and HPV coinfection is common among people living with HIV (PLWH) but disproportionally affects men who have sex with men (MSM) for whom the rate of persistent HPV infection and reinfection is noteworthy. The molecular interactions between HIV and HPV, as well as the interplay between both viruses and the immune system, are increasingly being understood. The immune dysfunction induced by HIV infection impairs the rate of HPV clearance and increases its oncogenic risk. Despite the availability of effective antiretroviral therapy (ART), the incidence of several HPV-related cancers is higher in PLWH, and the burden of persistent HPV-related disease has become a significant concern in an aging HIV population. Several public health strategies have been developed to reduce the transmission of HIV and HPV and mitigate the consequences of this type of coinfection. Universal HPV vaccination is the most effective preventive tool to reduce the incidence of HPV disease. In addition, screening programs for HPV-related cervical and vulvovaginal diseases in women are well-recognized strategies to prevent cervical cancer. Similarly, anal dysplasia screening programs are being implemented worldwide for the prevention of anal cancer among PLWH. Herein, the main epidemiological features and clinical implications of HIV and HPV coinfection are reviewed, focusing mainly on the relationship between HIV immune status and HPV-related diseases and the current strategies used to reduce the burden of HPV-related disease.

A two-sex model of human papillomavirus infection: Vaccination strategies and a case study

Vaccination is effective in preventing human papillomavirus (HPV) infection. It still remains debatable whether males should be included in a vaccination program and unclear how to allocate the vaccine in genders to achieve the maximum benefits. In this paper, we use a two-sex model to assess HPV vaccination strategies and use the data from Guangxi Province in China as a case study. Both mathematical analysis and numerical simulations show that the basic reproduction number, an important indicator of the transmission potential of the infection, achieves its minimum when the priority of vaccination is given to the gender with a smaller recruit rate. Given a fixed amount of vaccine, splitting the vaccine evenly usually leads to a larger basic reproduction number and a higher prevalence of infection. Vaccination becomes less effective in reducing the infection once the vaccine amount exceeds the smaller recruit rate of the two genders. In the case study, we estimate the basic reproduction number is 1.0333 for HPV 16/18 in people aged 15-55. The minimal bivalent HPV vaccine needed for the disease prevalence to be below 0.05% is 24050 per year, which should be given to females. However, with this vaccination strategy it would require a very long time and a large amount of vaccine to achieve the goal. In contrast with allocating the same vaccine amount every year, we find that a variable vaccination strategy with more vaccine given in the beginning followed by less vaccine in later years can save time and total vaccine amount. The variable vaccination strategy illustrated in this study can help to better distribute the vaccine to reduce the HPV prevalence. Although this work is for HPV infection and the case study is for a province in China, the model, analysis and conclusions may be applicable to other sexually transmitted diseases in other regions or countries.

Estimation of mid-and long-term benefits and hypothetical risk of Guillain-Barre syndrome after human papillomavirus vaccination among boys in France: A simulation study

BACKGROUND

The burden of human papillomavirus (HPV) infection can be substantially reduced through vaccination of girls, and gender-neutral policies are being adopted in many countries to accelerate disease control among women and expand direct benefits to men. Clinical direct benefit of boys HPV vaccination has been established for ano-genital warts and anal cancer. HPV vaccines are considered safe, but an association with Guillain-Barre syndrome has been found in French reimbursement and hospital discharge data.

METHODS

We conducted a Monte-Carlo simulation assuming a stable French population of 11- to 14-year-old boys, adult men and men having sex with men. We modelled and quantified the mid-term benefits as the annually prevented ano-genital warts among the 8.72 M men aged 15-35 years and the long-term benefits as the annually prevented anal cancer cases among the 17.4 M men aged 25-65 years. We also estimated the number of Guillain-Barre syndrome cases hypothetically induced by vaccination.

RESULTS

With a vaccine coverage of 30%, an annual number of 9310 (95% uncertainty interval [7050-11,200]) first ano-genital warts episodes among the 8.72 M men aged 15-35 years are prevented. According to more or less optimistic hypotheses on the proportion of HPV cancers covered by the vaccine, between 15.1 [11.7-17.7] and 19.2 [15.0-22.6] cases of anal cancer among the 17.4 M men aged 25-65 years would be annually avoided. Among men having sex with men, the corresponding figures were 1907 (1944-2291) for ano-genital warts and between 2.0 [0.23-4.5] and 2.6 [0.29-5.7] for anal cancer. Among 11- to 14-year-old boys, 0.82 (0.15-2.3) Guillain-Barre syndrome cases would be induced annually.

INTERPRETATION

A long-term program of HPV vaccination among boys in France would avoid substantially more cancer cases than hypothetically induce Guillain-Barre syndrome cases, in the general and specifically the homosexual population. Additional benefits may arise with the possible vaccine protection against oro-laryngeal and -pharyngeal cancer.