Evaluation of vaccination herd immunity effects for anogenital warts in a low coverage setting with human papillomavirus vaccine-an interrupted time series analysis from 2005 to 2010 using health insurance data

The impact of Germany's human papillomavirus immunization program on HPV-related anogenital diseases: a retrospective analysis of claims data from statutory health insurances

PURPOSE

Human papillomavirus (HPV) is the most common sexually transmitted infection, responsible for multiple HPV-related diseases, including almost all cervical cancers. The highly effective HPV vaccination has been recommended under the German HPV national immunization program (NIP) since 2007 and is reimbursed by health insurances. Vaccination uptake rates, however, remain suboptimal and data on the real-world impact of HPV vaccination in Germany are lacking. This study aims to demonstrate the population-level impact of Germany's NIP on HPV-related anogenital diseases among young women.

METHODS

Retrospective claims data analysis using a classic impact study design comparing disease prevalence among 28- to 33-year-old women before and after introduction of the HPV-immunization program in Germany. Claims data representing approximately two thirds of German health insurances were used. HPV-related disease outcomes included cervical cancer and high grade precancers (cervical intraepithelial neoplasia (CIN) 2+), anogenital warts, as well as vulvar, vaginal, and anal precancer/cancer.

RESULTS

Significant declines were seen for CIN2+, anogenital warts, and vaginal precancer/cancer. Prevalence of CIN2+ declined 51.1% from 0.92% (95% CI = 0.78%, 1.08%) to 0.45% (95% CI = 0.38%, 0.53%). There was a 38.6% decline in anogenital warts prevalence from 0.44% (95% CI = 0.36%, 0.54%) to 0.27% (95% CI = 0.22%, 0.32%) and 75.0% decline in vaginal precancer/cancer prevalence from 0.04% (95% CI = 0.02%, 0.07%) to 0.01% (95% CI = 0.00%, 0.02%).

CONCLUSION

The German HPV-immunization program has led to significant declines in female anogenital disease among young women in Germany, highlighting the importance of the vaccination. Moreover, the data suggest that increasing vaccination coverage in Germany could further strengthen the public-health impact of its HPV-immunization program.

HPV vaccination leads to decrease of anogenital warts and precancerous lesions of the cervix uteri in young women with low vaccination rates: a retrospective cohort analysis

BACKGROUND

Although the human papillomavirus (HPV) vaccine has been recommended in Germany for girls since 2007, no organised vaccination programme was introduced and HPV vaccine coverage remains low. We investigated the HPV vaccination rates from 2008 to 2018 and the effects of HPV vaccination on anogenital warts and precancerous lesions in young women in Bavaria, Germany, a state with low vaccination rates.

METHODS

Retrospective analyses of claims data from the Bavarian Association of Statutory Health Insurance Physicians (KVB) on females born between 1990 and 2009 (9 to 28 years old in 2018) were conducted to calculate vaccination rates by birth cohort, proportion of vaccine types administered and incidence of anogenital warts and precancerous lesions of the cervix uteri. 942 841 Bavarian females 9 to 28 years old with available information on HPV vaccination were included to calculate vaccination rates. For the outcome analyses, data from 433 346 females 19 to 28 years old were analysed. Hazard ratios (HR) were computed from univariable and multivariable Cox regression models comparing vaccinated and unvaccinated women, considering type of vaccine used and contraceptive prescription.

RESULTS

40·9% of 18-year-olds and only 13·3% of 12-year-olds were fully vaccinated in 2018 in Bavaria. Gardasil® and Gardasil9® were most commonly administered. Vaccinated compared to unvaccinated women had a lower incidence of anogenital warts and cervical lesions, however only small differences were detected between fully and partially vaccinated women. Fully vaccinated women had a 63% (HR 0·37 (95% confidence interval (CI) 0·34 to 0·40) and 23% (HR 0·77, 95%CI 0·71 to 0·84) lower risk of anogenital warts and cervical lesions, respectively. Women who were prescribed contraceptives prior to vaccination had a 49% higher risk of developing anogenital warts (HR 1·49, 95%CI 1·25 to 1·79) or cervical lesions (HR 1·49, 95%CI 1·27 to 1·75) compared to vaccinated women without contraceptive prescription.

CONCLUSIONS

The evaluation of the effects of HPV vaccination in Bavaria showed a promising decline of anogenital warts and precancerous lesions in vaccinated young women. However, an increase in vaccination rates is necessary to achieve a greater population impact in preventing HPV-related diseases.

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.

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.

Human papillomavirus vaccines effectiveness to prevent genital warts: A population-based study using health system integrated databases, 2009-2017

OBJECTIVES

To assess the effectiveness of the HPV vaccines in preventing genital warts (GW) in women aged 14-23 years and to estimate the incidence of GW in the whole population aged from 14 to 65.

DESIGN

Population-based retrospective cohort study using real-world data from the Valencia health system Integrated Databases (VID).

STUDY POPULATION

All subjects aged 14-65 years residing in the Valencia Region during 2009-2017 (n = 4,492,724), including a cohort of 563,240 females aged 14-23 years followed-up for the vaccine effectiveness (VE) estimations.

MAIN OUTCOME MEASURES

Incident cases of GW defined as the first activation of GW-related codes (ICD-9-CM 078.11 or ICD-10-CM A63.0) in hospital, primary and specialized care during the study period. Adjusted VE was estimated as (1-Relative Risk (RR)) × 100 by a negative binomial Bayesian model.

RESULTS

There were 23,049 cases of GW in the overall population and 2,565 in the females' cohort 14-23 years old. The incidence rate (IR) (in 100,000 persons-year) was 69.1 (95% CI 68.21-69.99) in the population overall, being higher in men (72.73; 95% CI 71.45-74.04). The IR of GW was 104.08 (95% CI 100.79-108.94) in the cohort of young women. The RR of GW increased with age from 14 to 21 years, reaching a plateau from 21 to 23. The VE of a complete schedule was 74% (95% CrI 68-79) for quadrivalent HPV vaccine (HPV4v). No effectiveness was seen with a full vaccination course with the bivalent HPV vaccine (HPV2v) in girls up to 21 years old. GW IR tends to be higher in unvaccinated cohorts covered by HPV4v vaccine than in unvaccinated cohorts not covered by HPV4v vaccine.

CONCLUSIONS

A complete HPV4v vaccination schedule was 74% effective in reducing GW in our population. Our results also suggest an indirect protection to unvaccinated and HPV2v vaccinated girls.

Significant decline of HPV 6 infection and genital warts despite low HPV vaccination coverage in young women in Germany: a long-term prospective, cohort data analysis

BACKGROUND

The introduction of human papillomavirus (HPV) vaccination has resulted in a remarkable decline of genital warts in women and men, but in Germany historical rates of vaccination are relatively low. We report long-term surveillance data on changes in HPV 6 and HPV 11 infection and the prevalence of genital warts in young women in the Wolfsburg HPV epidemiological study (WOLVES).

METHODS

Women born in 1983/84, 1988/89, and 1993/94 participated in four cohorts between 2009/10 and 2014/15. Quadrivalent vaccination coverage and prevalence of HPV 6/11 infection and genital warts are reported for participants aged 19-22 years and 24-27 years at the time of sample collection. Statistical analyses were done to compare similarly aged participants using 2 × 2 contingency tables (Röhmel-Mansmann unconditional exact test; two-side alpha of 0.05).

RESULTS

A total of 2456 women were recruited. Between 2010 and 2015, there was a statistically significant decrease in the prevalence of HPV 6 infection among women aged 24-27 years (2.1% versus 0.0%; P < 0.0001) and women aged 19-22 years (2.0% versus 0.0%; P = 0.0056). There was no significant decline in HPV 11 infection. In total, 52 of 2341 participants were diagnosed with genital warts. There was a statistically significant drop in the risk of developing genital warts in women aged 24-27 years between 2010 and 2015 (4.7% versus 1.7%, respectively; P = 0.0018). The overall risk of developing genital warts in women aged 19-27 years decreased from 3.1% in 2010 to 1.2% in 2015 (P = 0.0022).

CONCLUSIONS

An increase in vaccination coverage was associated with a decreased prevalence of genital warts in young women. A protective effect greater than herd immunity alone was seen despite low vaccination rates. Quadrivalent vaccine had a protective effect on genital HPV 6 infection and an almost fully protective effect on the development of genital warts in the youngest population.

Impact of a single-age cohort human papillomavirus vaccination strategy in Catalonia, Spain: Population-based analysis of anogenital warts in men and women

Extensive multiple-age cohort human papillomavirus (HPV) vaccination has proved to be highly effective. We aimed to determine the 8-year population impact of a female single-age cohort HPV vaccination programme on the incidence of anogenital warts (AGW). In 2008, Catalonia initiated a school-based quadrivalent HPV vaccination programme targeting 11-year-old girls, achieving coverage over 80%. Data on diagnoses of AGW and genital herpes were obtained from a population-based database of electronic health records covering 74% of the population. The annual incidence rates from 2009 to 2016 were calculated, stratified by age and sex using Joinpoint regression to estimate trends and annual percentage changes (APC). Among women aged 16-19 years, the AGW incidence decreased by 61% from 2012 to 2016 (APC -19.4%; 95% CI: -30.0 to -7.3). In contrast, the incidence of genital herpes in same-aged women increased throughout the study period (APC 11.1%; 95% CI: 7.2-15.2). Among men aged 20-22 years, the increasing incidence of AGW shifted to a downward trend in 2013 (APC 2009-2013: 17.0%; 95% CI: 8.2-26.5; and APC 2013-2016: -4.5%; 95% CI: -14.6 to 6.9). A similar pattern was observed among men aged 23-25 years (APC 2009-2014: 16.0%; 95% CI: 12.0-20.2; and APC 2014-2016: -6.0%; 95% CI: -18.4 to 8.3). In contrast to AGW, among men aged 20-25 years, the incidence of genital herpes increased over this period. Our study strongly suggests that a single-cohort HPV vaccination strategy with high vaccine uptake not only provides direct benefit in the vaccinated cohorts but also extends protection through a herd effect to unvaccinated men.

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.

Burden of HPV related anogenital diseases in young women in Germany - an analysis of German statutory health insurance claims data from 2012 to 2017

Background

Most individuals are infected with human papillomavirus (HPV) at least once in their lifetime. Infections with low-risk types can cause genital warts, whereas high-risk types can cause malignant tumors. The aim of this study was to determine the burden of anogenital diseases potentially related to HPV in young women based on German statutory health insurance claims data.

Methods

We conducted a retrospective claims data analysis using the “Institute for Applied Health Research Berlin” (InGef) Research Database, containing claims data from approximately 4 million individuals. In the period from 2012 to 2017 all women born in1989–1992, who were continuously insured between the age of 23–25 years were identified. Using ICD-10-GM codes (verified diagnosis in the outpatient sector or primary or secondary diagnosis in the inpatient sector) the administrative prevalence (95% confidence interval) of genital warts (A63.0), anogenital diseases grade I (K62.8, N87.0, N89.0, N90.0), grade II (N87.1, N89.1, N90.1) and grade III (D01.3, D06.-, D06.0, D07.1, D07.2, N87.2, N89.2, N90.2) was calculated (women with diagnosis divided by all women).

Results

From 2012 to 2017, a total of 15,358 (birth cohort 1989), 16,027 (birth cohort 1990), 14,748 (birth cohort 1991) and 14,862 (birth cohort 1992) women at the age of 23–25 were identified. A decrease of the administrative prevalence was observed in genital warts (1.30% (1.12–1.49) birth cohort 1989 vs. 0.94% (0.79–1.10) birth cohort 1992) and anogenital diseases grade III (1.09% (0.93–1.26) birth cohort 1989 vs. 0.71% (0.58–0.86) birth cohort 1992). In anogenital diseases grade III, this trend was especially observed for severe cervical dysplasia (N87.2) (0.91% (0.76–1.07) birth cohort 1989 vs. 0.60% (0.48–0.74) birth cohort 1992). In contrast, anogenital diseases grade I (1.41% (1.23–1.61) birth cohort 1989 vs. 1.31% (1.14–1.51) birth cohort 1992) and grade II (0.61% (0.49–0.75) birth cohort 1989 vs. 0.52% (0.42–0.65) birth cohort 1992) remained stable.

Conclusions

A decrease of the burden of anogenital disease potentially related to HPV was observed in the younger birth cohorts. This was observed especially for genital warts and anogenital diseases grade III. Further research to investigate this trend for the upcoming years in light of varying HPV vaccination coverage for newer birth cohorts is necessary.

Exploration of the effect of human papillomavirus (HPV) vaccination in a cohort of pregnant women in Montreal, 2010-2016

HPV vaccination efficacy has been shown in clinical trials but it is important to verify population level vaccine effectiveness (VE). We aimed to explore VE and herd effect using HPV infection data from a cohort study of Canadian pregnant women. We analyzed the baseline data of the HERITAGE study, which includes pregnant women recruited in Montreal between 2010-2012 and 2015–2016. Cervicovaginal samples self-collected in the first trimester were tested for 36 HPV types. Vaccination status was self-reported. VE and 95% confidence intervals (CI) were estimated by comparing the prevalence of HPV between vaccinated and unvaccinated women. Herd effect was explored by comparing HPV prevalence in unvaccinated women between the 2 recruitment periods. Adjusted ORs (95%CI) were estimated using exact logistic regression. The proportion of vaccinated women with at least one dose of 4vHPV was 7.5%. Although most of them were vaccinated after the onset of sexual activity, a high VE was found for HPV-16/18 (86.1% (95%CI: 15.0–99.7)). For HPV-6/11/16/18 and for HPV-31/33/45, VE was 61.9% (-23.5–92.6) and 57.0% (-47.7–92.0%), respectively. We also observed a non-statistically significant reduction in the prevalence of HPV-6/11/16/18 and HPV-31/33/45 among unvaccinated women recruited during the second recruitment period (adjusted OR: 0.8 (0.4–1.8) and 0.8 (0.3–1.7), respectively).

Population-level impact and herd effects following the introduction of human papillomavirus vaccination programmes: updated systematic review and meta-analysis

BACKGROUND

More than 10 years have elapsed since human papillomavirus (HPV) vaccination was implemented. We did a systematic review and meta-analysis of the population-level impact of vaccinating girls and women against human papillomavirus on HPV infections, anogenital wart diagnoses, and cervical intraepithelial neoplasia grade 2+ (CIN2+) to summarise the most recent evidence about the effectiveness of HPV vaccines in real-world settings and to quantify the impact of multiple age-cohort vaccination.

METHODS

In this updated systematic review and meta-analysis, we used the same search strategy as in our previous paper. We searched MEDLINE and Embase for studies published between Feb 1, 2014, and Oct 11, 2018. Studies were eligible if they compared the frequency (prevalence or incidence) of at least one HPV-related endpoint (genital HPV infections, anogenital wart diagnoses, or histologically confirmed CIN2+) between pre-vaccination and post-vaccination periods among the general population and if they used the same population sources and recruitment methods before and after vaccination. Our primary assessment was the relative risk (RR) comparing the frequency (prevalence or incidence) of HPV-related endpoints between the pre-vaccination and post-vaccination periods. We stratified all analyses by sex, age, and years since introduction of HPV vaccination. We used random-effects models to estimate pooled relative risks.

FINDINGS

We identified 1702 potentially eligible articles for this systematic review and meta-analysis, and included 65 articles in 14 high-income countries: 23 for HPV infection, 29 for anogenital warts, and 13 for CIN2+. After 5-8 years of vaccination, the prevalence of HPV 16 and 18 decreased significantly by 83% (RR 0·17, 95% CI 0·11-0·25) among girls aged 13-19 years, and decreased significantly by 66% (RR 0·34, 95% CI 0·23-0·49) among women aged 20-24 years. The prevalence of HPV 31, 33, and 45 decreased significantly by 54% (RR 0·46, 95% CI 0·33-0·66) among girls aged 13-19 years. Anogenital wart diagnoses decreased significantly by 67% (RR 0·33, 95% CI 0·24-0·46) among girls aged 15-19 years, decreased significantly by 54% (RR 0·46, 95% CI 0.36-0.60) among women aged 20-24 years, and decreased significantly by 31% (RR 0·69, 95% CI 0·53-0·89) among women aged 25-29 years. Among boys aged 15-19 years anogenital wart diagnoses decreased significantly by 48% (RR 0·52, 95% CI 0·37-0·75) and among men aged 20-24 years they decreased significantly by 32% (RR 0·68, 95% CI 0·47-0·98). After 5-9 years of vaccination, CIN2+ decreased significantly by 51% (RR 0·49, 95% CI 0·42-0·58) among screened girls aged 15-19 years and decreased significantly by 31% (RR 0·69, 95% CI 0·57-0·84) among women aged 20-24 years.

INTERPRETATION

This updated systematic review and meta-analysis includes data from 60 million individuals and up to 8 years of post-vaccination follow-up. Our results show compelling evidence of the substantial impact of HPV vaccination programmes on HPV infections and CIN2+ among girls and women, and on anogenital warts diagnoses among girls, women, boys, and men. Additionally, programmes with multi-cohort vaccination and high vaccination coverage had a greater direct impact and herd effects.

FUNDING

WHO, Canadian Institutes of Health Research, Fonds de recherche du Québec - Santé.

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.