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

Comparative Analysis of HPV16 Variants in the Untranslated Regulatory Region, L1, and E6 Genes among Vaccinated and Unvaccinated Young Women: Assessing Vaccine Efficacy and Viral Diversity

HPV16 is occasionally detected in vaccinated women who received the bivalent HPV16/18 vaccine, usually at low viral loads. This study explored potential differences in HPV16 variants between vaccinated and unvaccinated women. HPV16-postive viral loads were detected in 1.9% (17/875) and 13% (162/760) of vaccinated and unvaccinated women, respectively, showcasing the vaccine's high efficacy. The L1, E6, and URR regions of HPV16 were sequenced from genital swabs from 16 vaccinated and 25 unvaccinated women in the HAVANA (HPV Among Vaccinated And Non-vaccinated Adolescents) study. The majority of HPV16 variants from vaccinated and unvaccinated women clustered similarly with sub-lineages A1 and A2. Additionally, a separate cluster within lineage A was found, with the variants sharing the L1-located SNP A753G (synonymous) and the URR-located SNP T340C, which did not occur in the other variants. Furthermore, four variants from vaccinated women had relatively long branches, but were not characterized by specific SNPs. The frequency of G712A in the URR was the only SNP observed to be marginally higher among vaccinated women than unvaccinated women. Non-synonymous SNPs T266A in the FG-loop of L1 and L83V in E6 were common among variants from vaccinated and unvaccinated women, but present in similar frequencies. In conclusion, the detection of HPV16 in vaccinated (and unvaccinated) women seemed to be the result of random circulation within this study population.

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.

Impact and Cost-Effectiveness of Alternative Human Papillomavirus Vaccines for Preadolescent Girls in Mozambique: A Modelling Study

Mozambique has one of the highest rates of cervical cancer in the world. Human papillomavirus (HPV) vaccination was introduced in 2021. This study evaluated the health and economic impact of the current HPV vaccine (GARDASIL^® hereafter referred to as GARDASIL-4) and two other vaccines (CECOLIN^® and CERVARIX^®) that could be used in the future. A static cohort model was used to estimate the costs and benefits of vaccinating girls in Mozambique over the period 2022-2031. The primary outcome measure was the incremental cost per disability-adjusted life-year averted from a government perspective. We conducted deterministic and probabilistic sensitivity analyses. Without cross-protection, all three vaccines averted approximately 54% cervical cancer cases and deaths. With cross-protection, CERVARIX averted 70% of cases and deaths. Without Gavi support, the discounted vaccine program costs ranged from 60 million to 81 million USD. Vaccine program costs were approximately 37 million USD for all vaccines with Gavi support. Without cross-protection, CECOLIN was dominant, being cost-effective with or without Gavi support. With cross-protection and Gavi support, CERVARIX was dominant and cost-saving. With cross-protection and no Gavi support, CECOLIN had the most favorable cost-effectiveness ratio. Conclusions: At a willingness-to-pay (WTP) threshold set at 35% of Gross Domestic Product (GDP) per capita, HPV vaccination is cost-effective in Mozambique. The optimal vaccine choice depends on cross-protection assumptions.

Ability of epidemiological studies to monitor HPV post-vaccination dynamics: a simulation study

Genital human papillomavirus (HPV) infections are caused by a broad diversity of genotypes. As available vaccines target a subgroup of these genotypes, monitoring transmission dynamics of nonvaccine genotypes is essential. After reviewing the epidemiological literature on study designs aiming to monitor those dynamics, we evaluated their abilities to detect HPV-prevalence changes following vaccine introduction. We developed an agent-based model to simulate HPV transmission in a heterosexual population under various scenarios of vaccine coverage and genotypic interaction, and reproduced two study designs: post-vs.-prevaccine and vaccinated-vs.-unvaccinated comparisons. We calculated the total sample size required to detect statistically significant prevalence differences at the 5% significance level and 80% power. Although a decrease in vaccine-genotype prevalence was detectable as early as 1 year after vaccine introduction, simulations indicated that the indirect impact on nonvaccine-genotype prevalence (a decrease under synergistic interaction or an increase under competitive interaction) would only be measurable after >10 years whatever the vaccine coverage. Sample sizes required for nonvaccine genotypes were >5 times greater than for vaccine genotypes and tended to be smaller in the post-vs.-prevaccine than in the vaccinated-vs.-unvaccinated design. These results highlight that previously published epidemiological studies were not powerful enough to efficiently detect changes in nonvaccine-genotype prevalence.

Evolution of human papilloma virus prevalence in a highly vaccinated region in Belgium: a retrospective cohort study in Flemish women (2010-2019)

OBJECTIVE

In order to lower the incidence of cervical cancer, vaccines against high-risk types of the human papilloma virus (hrHPV) were approved and brought on the market in 2007, with a partial reimbursement for Belgian citizens younger than 18 years old. Since 2010, a school-based vaccination program ensures a high vaccination coverage in young women. In this study, the impact of the Belgian vaccination program on the prevalence of HPV 16/18 is studied, together with the evolution of the prevalence of other hrHPV types and precancerous lesions.

METHODS

Results of HPV typing and cytology in papanicolaou-smears from women aged 20-23 years taken between 2010 and 2019 were used. An older, nonvaccinated group of women of 40-45 years old served as a control group.

RESULTS

A significant decrease in prevalence of HPV types 16 and 18 was found in the 20-23-years-old women, whereas no decrease was found in the age group 40-45. Alongside this decrease, a significant decrease in prevalence of subtypes 6, 11 and 31 was observed, whereas type 31 is not included in the administered vaccines. Remarkably, there was no decrease in prevalence of cytological abnormalities in the study group during this study. There was even an increase in prevalence of high-risk types 53, 58 and 67.

CONCLUSION

These findings emphasise the need to maintain the screening programs, even in areas with high vaccination coverage.

Human Papillomavirus Vaccine Impact and Effectiveness Through 12 Years After Vaccine Introduction in the United States, 2003 to 2018

BACKGROUND

Human papillomavirus (HPV) vaccination was introduced in 2006 for females and in 2011 for males.

OBJECTIVE

To estimate vaccine impact and effectiveness against quadrivalent HPV vaccine (4vHPV)-type prevalent infection among sexually experienced U.S. females and vaccine effectiveness for sexually experienced U.S. males.

DESIGN

NHANES (National Health and Nutrition Examination Survey) conducted in 2003 to 2006 (prevaccine era) and in 2007 to 2010, 2011 to 2014, and 2015 to 2018 (vaccine eras).

SETTING

Nationally representative U.S. surveys.

PARTICIPANTS

Sexually experienced participants aged 14 to 24 years.

INTERVENTION

U.S. HPV vaccination program.

MEASUREMENTS

Participant-collected cervicovaginal and penile specimens were tested for HPV DNA. The prevalences of 4vHPV and non-4vHPV types were estimated in each era for females and in 2013 to 2016 for males. Prevalences among the female population overall, vaccinated females, and unvaccinated females were compared in vaccine eras versus the prevaccine era (vaccine impact). Within each vaccine era, prevalence among vaccinated females was compared with that among unvaccinated females (vaccine effectiveness). Vaccine impact and effectiveness were estimated as (1 - prevalence ratio) · 100.

RESULTS

Among sexually experienced females aged 14 to 24 years, the impact on 4vHPV-type prevalence in 2015 to 2018 was 85% overall, 90% among vaccinated females, and 74% among unvaccinated females. No significant declines were found in non-4vHPV-type prevalence. Vaccine effectiveness ranged from 60% to 84% during vaccine eras for females and was 51% during 2013 to 2016 for males.

LIMITATION

Self- or parent-reported vaccination history and small numbers in certain subgroups limited precision.

CONCLUSION

Nationally representative data show increasing impact of the vaccination program and herd protection. Vaccine effectiveness estimates will be increasingly affected by herd effects.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention.

Changes in HPV16/18 Prevalence among Unvaccinated Women with Cervical Intraepithelial Neoplasia in Japan: Assessment of Herd Effects following the HPV Vaccination Program

Since the human papillomavirus (HPV) vaccination program for Japanese girls aged 12–16 years began in 2010, vaccination uptake has been low in women born before 1993 but high (approximately 70%) in those born during 1994–1999. We previously compared the prevalence of vaccine types HPV16 and HPV18 in cervical intraepithelial neoplasia grade 1–3 (CIN1–3) or adenocarcinoma in situ (AIS) between vaccinated and unvaccinated cohorts and found direct protection effects among vaccinated women in Japan. In this study, we focused on changes in HPV16/18 prevalence among “unvaccinated” cohorts with CIN/AIS. We analyzed HPV16/18 prevalence among 5051 unvaccinated women aged <40 years, newly diagnosed with CIN/AIS during 2012–2021 for time trends. Declining trends in HPV16/18 prevalence over 9 years were observed in CIN1 (36.0–10.0%, Ptrend = 0.03) and CIN2–3/AIS (62.5–36.4%, Ptrend = 0.07) among women aged <25 years. HPV16/18 prevalence in CIN1 and CIN2–3/AIS diagnosed at age 20–24 years was lower in 1994–1999 birth cohorts compared with 1988–1993 birth cohorts (4.5% vs. 25.7% for CIN1 and 40.0% vs. 58.1% for CIN2–3/AIS, both p = 0.04). Significant reduction in HPV16/18 prevalence among young unvaccinated women with CIN1 and CIN2–3/AIS suggests herd effects of HPV vaccination in Japan.

On the Elimination of Infections Related to Oncogenic Human Papillomavirus: An Approach Using a Computational Network Model

Cervical cancer is the fourth most common malignancy in women worldwide, although it is preventable with prophylactic HPV vaccination. HPV transmission-dynamic models can predict the potential for the global elimination of cervical cancer. The random network model is a new approach that allows individuals to be followed, and to implement a given vaccination policy according to their clinical records. We developed an HPV transmission-dynamic model on a lifetime sexual partners network based on individual contacts, also accounting for the sexual behavior of men who have sex with men (MSM). We analyzed the decline in the prevalence of HPV infection in a scenario of 75% and 90% coverage for both sexes. An important herd immunity effect for men and women was observed in the heterosexual network, even with 75% coverage. However, HPV infections are persistent in the MSM population, with sustained circulation of the virus among unvaccinated individuals. Coverage around 75% of both sexes would be necessary to eliminate HPV-related conditions in women within five decades. Nevertheless, the variation in the decline in infection in the long term between a vaccination coverage of 75% and 90% is relatively small, suggesting that reaching coverage of around 70-75% in the heterosexual network may be enough to confer high protection. Nevertheless, HPV elimination may be achieved if men's coverage is strictly controlled. This accurate representation of HPV transmission demonstrates the need to maintain high HPV vaccination coverage, especially in men, for whom the cost-effectiveness of vaccination is questioned.