Prevalence of Human Papillomavirus and Estimation of Human Papillomavirus Vaccine Effectiveness in Thimphu, Bhutan, in 2011-2012 and 2018 : A Cross-sectional Study

Population-level cancer screening and cancer care in Bhutan, 2020-2023: a review

Screening of cancers is an important intervention in reducing the incidence and mortality related to cancers. Bhutan is one small country that is witnessing an increasing incidence and mortality related to cancers. The government implemented a time-bound population-level screening for gastric, cervical and breast cancers from 2020 to 2023 with an overall coverage of 91.2% of the eligible population. Among 370,225 individuals screened for H pylori, 32.4% tested positive; among 53,182 who underwent upper gastrointestinal endoscopy and biopsy, 255 (0.07%) had gastric cancer. Among 10,749 tested for HPV DNA, 9.3% were positive; among 9887 evaluated with colposcopy and biopsy, 154 (0.13%) had cervical cancer. For breast cancer screening, 72,283 underwent clinical breast examination, 845 mammography and cancer was detected in 73 (0.10%) individuals. In this article, we review how Bhutan implemented a population-level cancer screening programme with on boarding of multiple stakeholders and the participation of people across all districts.

Human papillomavirus vaccine effectiveness by age at vaccination: A systematic review

Human papillomavirus (HPV) vaccines work by preventing infections prior to natural exposure. Thus, it is likely more effective at younger ages, and it is important to understand how effectiveness might be diminished when administered at older ages. We conducted a systematic review of HPV vaccine effectiveness studies published between 2007 and 2022 that included an analysis of effectiveness against vaccine-type HPV infections, anogenital warts, cervical abnormalities and cervical cancer by age at vaccine initiation or completion. Searching multiple databases, 21 studies were included and results were summarized descriptively. Seventeen studies found the highest vaccine effectiveness in the youngest age group. Vaccine effectiveness estimates for younger adolescents ages 9-14 years ranged from approximately 74% to 93% and from 12% to 90% for adolescents ages 15-18 years. These results demonstrate that the HPV vaccine is most effective against HPV-related disease outcomes when given at younger ages, emphasizing the importance of on-time vaccination.

Human papillomavirus vaccine effect against human papillomavirus infection in Rwanda: evidence from repeated cross-sectional cervical-cell-based surveys

BACKGROUND

Rwanda was the first African country to implement national human papillomavirus (HPV) vaccination (against types HPV6, 11, 16, and 18). In 2011, a school-based catch-up programme was initiated to vaccinate girls aged younger than 15 years but it also reached older girls in schools. We aimed to estimate the population-level effect of HPV vaccination on HPV prevalence.

METHODS

Cross-sectional surveys were done between July, 2013, and April, 2014 (baseline), and between March, 2019, and December, 2020 (repeat), in sexually active women aged 17-29 years at health centres in the Nyarugenge District of Kigali, Rwanda. HPV prevalence was assessed in cervical cell samples collected by a health-care worker in PreservCyt solution (Cytyc, Boxbourough, MA, USA) and tested using a general primer (GP5+ or GP6+)-mediated PCR. Adjusted overall, total, and indirect (herd immunity) vaccine effectiveness was computed as the percentage of HPV detection among all women and among unvaccinated women.

FINDINGS

1501 participants completed the baseline survey and 1639 completed the repeat survey. HPV vaccine-type prevalence in participants aged 17-29 years decreased from 12% (173 of 1501) in the baseline survey to 5% (89 of 1639) in the repeat survey, with an adjusted overall vaccine effectiveness of 47% (95% CI 31 to 60) and an adjusted indirect vaccine effectiveness of 32% (9 to 49). Among participants aged 17-23 years, who were eligible for catch-up vaccination, the adjusted overall vaccine effectiveness was 52% (35 to 65) and the adjusted indirect vaccine effectiveness was 36% (8 to 55), with important heterogeneity according to education (overall vaccine effectiveness was 68% [51 to 79] in participants with ≥6 years of school completed and 16% [-34 to 47] in those with <6 years) and HIV status (overall vaccine effectiveness was 55% [36 to 69] for HIV-negative participants and 24% [-62 to 64] for HIV-positive participants).

INTERPRETATION

In Rwanda, the prevalence of vaccine-targeted HPV types has been significantly decreased by the HPV vaccine programme, most notably in women who were attending school during the catch-up programme in 2011. HPV vaccine coverage and population-level impact is expected to increase in future cohorts who are eligible for routine HPV vaccination at age 12 years.

FUNDING

Bill & Melinda Gates Foundation.

Changes in genital Human Papillomavirus (HPV) prevalence among urban females a decade after the Malaysian HPV vaccination program

To increase the coverage of HPV vaccination, Malaysia implemented a national school-based vaccination program for all 13-year-old girls in 2010. Two years later, a clinic-based catch-up program was started for 16 to 21-year-old girls. We assessed the prevalence of a range of HPV genotypes, among a sample of urban women within the age groups of 18-24 and 35-45 years in 2019-2020, a decade into the national vaccination program. The HPV prevalence was then compared to that reported in an unvaccinated population in 2013-2015. We sampled a total of 1134 participants, comprising of 277 women aged 18-24 years and 857 women aged 35-45 years, from several urban clinics in the state of Selangor. Participants provided a self-acquired vaginal sample for HPV genotyping. Comprehensive sociodemographic and vaccination history were collected. The HPV vaccination coverage among women in the younger age group increased from 9.3% in 2013-2015 to 75.5% in 2019-2020. The prevalence of vaccine-targeted HPV16/18 decreased 91% (CI: 14.5%-99.0%) among the younger women, from 4.0% in 2013-2015 to 0.4% in 2019-2020. There was also an 87% (CI: 27.5%-97.5%) reduction in HPV6/11/16/18. There was no difference in the prevalence of non-vaccine targeted HPV genotypes among younger women. The HPV prevalence among older women, for both vaccine targeted and non-vaccine targeted genotypes in 2019-2020, did not differ from 2013-2015. The observed decline in prevalence of vaccine-targeted HPV genotype among younger women a decade after the national HPV vaccination program is an early indication of its effectiveness in reducing the burden of cervical cancer.

The impact of HPV vaccination beyond cancer prevention: effect on pregnancy outcomes

While the benefits of human papillomavirus (HPV) vaccination relating to cervical cancer prevention have been widely documented, recent published evidence is suggestive of an impact on adverse pregnancy outcomes (APOs) in vaccinated mothers and their infants, including a reduction in rates of preterm births and small for gestational age infants. In this review, we examine this evidence and the possible mechanisms by which HPV vaccination may prevent these APOs. Large-scale studies linking HPV vaccination status with birth registries are needed to confirm these results. Potential confounding factors to consider in future analyses include other risk factors for APOs, and historical changes in both the management of cervical precancerous lesions and prevention of APOs. If confirmed, these additional benefits of HPV vaccination in reducing APO rates will be of global significance, due to the substantial health, social and economic costs associated with APOs, strengthening the case for worldwide HPV immunization.

Global estimates of expected and preventable cervical cancers among girls born between 2005 and 2014: a birth cohort analysis

BACKGROUND

WHO has launched an initiative aiming to eliminate cervical cancer as a public health problem. Elimination is a long-term target that needs long-lasting commitment. To support local authorities in implementing human papillomavirus (HPV) vaccination, we provide regional and country-specific estimates of cervical cancer burden and the projected impact of HPV vaccination among today's young girls who could develop cervical cancer if not vaccinated.

METHODS

The expected number of cervical cancer cases in the absence of vaccination among girls born between 2005 and 2014 was quantified by combining age-specific incidence rates from GLOBOCAN 2018 and cohort-specific mortality rates by age from UN demographic projections. Preventable cancers were estimated on the basis of HPV prevalence reduction attributable to vaccination and the relative contribution of each HPV type to cervical cancer incidence. We assessed the number of cervical cancer cases preventable through vaccines targeting HPV types 16 and 18, with and without cross-protection, and through vaccines targeting HPV types 16, 18, 31, 33, 45, 52, and 58.

FINDINGS

Globally, without vaccination, the burden of cervical cancer in these birth cohorts is expected to reach 11·6 million (95% uncertainty interval 11·4-12·0) cases by 2094. Approximately 75% of the burden will be concentrated in 25 countries mostly located in Africa and Asia, where the future number of cases is expected to increase manyfold, reaching 5·6 million (5·4-6·0) cases in Africa and 4·5 million (4·4-4·6) cases in Asia. Worldwide immunisation with an HPV vaccine targeted to HPV types 16 and 18, with cross-protection against HPV types 31, 33, and 45, could prevent about 8·7 million (8·5-9·0) cases.

INTERPRETATION

Detailed estimates of the increasing burden of cervical cancer and projected impact of HPV vaccination is of immediate relevance to public health decision makers. Shifting the focus of projections towards recently born girls who could develop cervical cancer if not vaccinated is fundamental to overcome stakeholders' hesitancy towards HPV vaccination.

FUNDING

Bill & Melinda Gates Foundation, Canadian Institutes of Health Research.

Impact of Human Papillomavirus Vaccination, Rwanda and Bhutan

Rwanda and Bhutan, 2 low- and middle-income countries, implemented primarily school-based national human papillomavirus (HPV) vaccination in 2011 (Rwanda) and 2010 (Bhutan). We estimated vaccination effectiveness through urine-based HPV prevalence surveys in schools in 2013–2014 and 2017. In Rwanda, 912 participants from baseline surveys and 1,087 from repeat surveys were included, and in Bhutan, 973 participants from baseline surveys and 909 from repeat surveys were included. The overall effectiveness against vaccine-targeted HPV types (i.e., HPV-6/11/16/18) was 78% (95% CI 51%–90%) in Rwanda, and 88% (6%–99%) in Bhutan and against other α-9 types was 58% (21–78) in Rwanda and 63% (27–82) in Bhutan. No effect against other HPV types was detectable. Prevalence of vaccine-targeted HPV types decreased significantly, as well as that of other α-9 types, suggesting cross-protection. These findings provide direct evidence from low- and middle-income countries of the marked effectiveness of high-coverage school-based, national HPV vaccination programs.

Current Updates on Cancer-Causing Types of Human Papillomaviruses (HPVs) in East, Southeast, and South Asia

Simple Summary

Among the over 200 human papillomavirus (HPV) genotypes identified, approximately 15 of them can cause human cancers. In this review, we provided an updated overview of the distribution of cancer-causing HPV genotypes by countries in East, Southeast and South Asia. Besides the standard screening and treatment methods employed in these regions, we unravel HPV detection methods and therapeutics utilised in certain countries that differ from other part of the world. The discrepancies may be partly due to health infrastructure, socio-economy and cultural diversities. Additionally, we highlighted the area lack of study, particularly on the oncogenicity of HPV genotype variants of high prevalence in these regions.

Abstract

Human papillomavirus (HPV) infection remains one of the most prominent cancer-causing DNA viruses, contributing to approximately 5% of human cancers. While association between HPV and cervical cancers has been well-established, evidence on the attribution of head and neck cancers (HNC) to HPV have been increasing in recent years. Among the cancer-causing HPV genotypes, HPV16 and 18 remain the major contributors to cancers across the globe. Nonetheless, the distribution of HPV genotypes in ethnically, geographically, and socio-economically diverse East, Southeast, and South Asia may differ from other parts of the world. In this review, we garner and provide updated insight into various aspects of HPV reported in recent years (2015–2021) in these regions. We included: (i) the HPV genotypes detected in normal cancers of the uterine cervix and head and neck, as well as the distribution of the HPV genotypes by geography and age groups; (ii) the laboratory diagnostic methods and treatment regimens used within these regions; and (iii) the oncogenic properties of HPV prototypes and their variants contributing to carcinogenesis. More importantly, we also unveil the similarities and discrepancies between these aspects, the areas lacking study, and the challenges faced in HPV studies.

Gender-neutral HPV elimination, cervical cancer screening, and treatment: Experience from Bhutan

Cervical cancer is preventable and also curable when detected early and treated adequately, yet it remains a leading cause of morbidity and mortality among women. In Bhutan, cervical cancer is the most common cancer among women. Bhutan was the first country among the low- and middle-income economies to have instituted a national HPV vaccination program, in 2010, and has achieved >90% coverage. In 2019, Bhutan launched a cervical cancer elimination flagship program well ahead of WHO's launch of the global strategy for accelerated elimination of cervical cancer. Bhutan initiated vaccination of adolescent boys and adopted a gender-neutral vaccination program beginning September 2020 through its well-established network of primary healthcare centres. The flagship program aims to screen women aged 30-69 years with HPV testing using liquid-based cytology (LBC) as triaging for screen positive women. For women aged 25-29 years, LBC will be continued as per American Society of Colposcopy and Cervical Pathology guidelines. Colposcopy and treatment will be performed in camps to decrease loss of follow up of screen positive women. This program is also expected to improve early diagnosis of cervical cancer and provide timely and adequate cancer treatment and palliative care services. This article reviews the progress made and the challenges facing the 2030 cervical cancer elimination targets in Bhutan.

Postvaccination prevalence of vaccine-Human Papillomavirus (vHPV) genotypes among the target population: A systematic review and meta-analysis

Human Papillomavirus (HPV) vaccines are safe and are highly effective in reducing the prevalence of HPV infections and subsequent HPV associated diseases in the target population. A systematic review and meta-analysis was carried out searching electronic databases for articles published between January 2007 and September 2020 reporting the prevalence estimates of vaccine HPV (vHPV) types in women who had received one or more doses of quadrivalent or bivalent vaccines. This systematic review was based on standard systematic review guidelines and the meta-analysis was performed by pooling the HPV vaccine type prevalence data with 95% confidence interval (CI) among 16,929 young women who had received the prophylactic HPV vaccines before the age of 27 years. The overall pooled prevalence of vHPV types was.0.04 (95% CI: 0.02, 0.05). The meta-analysis concludes that prophylactic HPV vaccination before the age of 27 years results in a decline of vHPV types in young women.

Human papillomavirus vaccination uptake in low-and middle-income countries: a meta-analysis

BACKGROUND

The proportion of incident cases of HPV-attributable cancers is highest in the low- and middle-income countries (LMICs) but many are yet to initiate HPV vaccination programs. This meta-analysis was performed to assess the uptake of HPV vaccination in LMICs at the beginning of the global strategy to eliminate cervical cancer and describes the gaps and challenges.

METHODS

A systematic search was conducted in PubMed, EMBASE, Scopus, Web of Science, and CENTRAL databases for observational studies that reported the uptake of HPV vaccination until October 2020. The meta-analysis was done using a random-effects model to assess the pooled estimate of HPV uptake. CRD42021218429.

FINDINGS

During 2008-2020, an estimated 3.3 million females received at least one dose of HPV vaccine with 61.69% of the target population vaccinated. In countries with high uptake, the pooled estimate of uptake was higher in females than males (45.48% vs 8.45%) and showed significant decline in 2015-2020 compared to 2006-2014 (89.03% vs 41.48%). In countries with low uptake, the estimate of uptake was low in both males and females (5.31% vs 2.93%) and showed increase in uptake in 2015-2020 compared to 2006-2014 (0.76% vs 5.22%). In countries with high uptake, compared to routine programs, the estimate was higher when delivered through demonstration programs (89.94% vs 59.74%).

INTERPRETATION

The major concern was a significant drop in the uptake in countries that started with high uptake, challenges in the maintenance of vaccine uptake, sustainability of funding and the lack of standard monitoring and reporting.

Surveillance systems for monitoring cervical cancer elimination efforts: Focus on HPV infection, cervical dysplasia, cervical screening and treatment

In order to achieve the global elimination of cervical cancer as a public health problem, close surveillance of progress in public health and clinical activities and outcomes across the three pillars of vaccination, screening and treatment will be required. Surveillance should ideally occur within an integrated system that is planned, funded, and regularly evaluated to ensure it is providing timely, accurate and relevant feedback for action. In this paper, we conceptualise the main public health surveillance objectives as process and outcome measures in each of the three pillars. Process measures include coverage/participation measures for vaccination, screening and treatment alongside the ongoing assessment of the quality and reach of these programs and activities. Outcome measures related to the natural history of human papillomavirus (HPV) infection include HPV infection prevalence, precursor cervical lesions and cervical cancers (including stage at diagnosis, cancer incidence and mortality). These outcome measures can be used for monitoring the effectiveness of the three core activities in the short, medium and long term to assess whether these interventions are effectively reducing their occurrence. We discuss possible methods for the surveillance of these measures in the context of country capacity, drawing from examples in Australia, the USA and in low and middle income countries.

Monitoring HPV vaccine impact on cervical disease: Status and future directions for the era of cervical cancer elimination

Post-licensure monitoring of the impact of HPV vaccines is critical to track the progress being made toward cervical cancer elimination and to identify areas where further progress can accelerate the achievement of this important public health goal. Over the past decade, a large body of evidence has revealed convincing benefits of HPV vaccination in preventing cervical infections and precancers at the individual-level (i.e., direct effectiveness) as well as in reducing the population-level burden of disease (i.e., overall effectiveness). At this time, effectiveness of the vaccines on preventing cervical cancer is just beginning to emerge given that there is a prolonged latency period for invasive disease. As we enter the era of cervical cancer elimination, these early and promising results may be expected in other countries in the near future. Thus, monitoring the direct and overall effectiveness for cervical cancer is an urgent research priority. In this article, we summarize what is known about the effectiveness of HPV vaccines on precancerous outcomes, and we highlight considerations for continuing these important public health activities going forward to monitor progress toward cervical cancer elimination.