The early benefits of human papillomavirus vaccination on cervical dysplasia and anogenital warts

Risk of progression of cervical intraepithelial neoplasia grade 2 in human papillomavirus-vaccinated and unvaccinated women: a population-based cohort study

BACKGROUND

Many countries have implemented active surveillance (ie, leaving the lesion untreated) as an option among younger women with cervical intraepithelial neoplasia grade 2 because regression rates are high and excisional treatment increases the risk for preterm birth in subsequent pregnancies. However, early identification of women at increased risk for progression to cervical intraepithelial neoplasia grade 3 or worse is important to ensure timely treatment. Because women who have received a human papillomavirus vaccine have a lower risk for cervical cancer, they may have a lower risk for progression of untreated cervical intraepithelial neoplasia grade 2 to cervical intraepithelial neoplasia grade 3 or worse.

OBJECTIVE

This study aimed to investigate if women who received a human papillomavirus vaccine and who are undergoing active surveillance for cervical intraepithelial neoplasia grade 2 are less likely to progress to cervical intraepithelial neoplasia grade 3 or worse when compared with women who did not receive the vaccine.

STUDY DESIGN

We conducted a population-based cohort study in Denmark using data from national health registers. We identified all women aged 18 to 40 years who were undergoing active surveillance for cervical intraepithelial neoplasia grade 2 from January 1, 2007, to December 31, 2020. Women with a previous record of cervical intraepithelial neoplasia grade 2 or worse, hysterectomy, or a loop electrosurgical excision procedure were excluded. Exposure was defined as having received ≥1 dose of a human papillomavirus vaccine at least 1 year before the cervical intraepithelial neoplasia grade 2 diagnosis. We used cumulative incidence functions to estimate the risk for progression to cervical intraepithelial neoplasia grade 3 or worse within 28 months using hysterectomy, emigration, and death as competing events. We used modified Poisson regression to calculate crude and adjusted relative risks of progression during the 28-month surveillance period. Results were stratified by age at vaccination and adjusted for index cytology, disposable income, and educational level.

RESULTS

The study population consisted of 7904 women of whom 3867 (48.9%) were vaccinated at least 1 year before a diagnosis of cervical intraepithelial neoplasia grade 2. At the time of cervical intraepithelial neoplasia grade 2 diagnosis, women who were vaccinated were younger (median age, 25 years; interquartile range, 23-27 years) than those who were not (median age, 29 years; interquartile range, 25-33 years). The 28-month cumulative risk for cervical intraepithelial neoplasia grade 3 or worse was significantly lower among women who were vaccinated before the age of 15 years (22.9%; 95% confidence interval, 19.8-26.1) and between the ages of 15 and 20 years (31.5%; 95% confidence interval, 28.8-34.3) when compared with women who were not vaccinated (37.6%; 95% confidence interval, 36.1-39.1). Thus, when compared with women who were not vaccinated, those who were vaccinated before the age of 15 years had a 35% lower risk for progression to cervical intraepithelial neoplasia grade 3 or worse (adjusted relative risk, 0.65; 95% confidence interval, 0.57-0.75), whereas women who were vaccinated between the ages of 15 and 20 years had a 14% lower risk (adjusted relative risk, 0.86; 95% confidence interval, 0.79-0.95). For women who were vaccinated after the age of 20 years, the risk was comparable with that among women who were not vaccinated (adjusted relative risk, 1.02; 95% confidence interval, 0.96-1.09).

CONCLUSION

Women who were vaccinated and who were undergoing active surveillance for cervical intraepithelial neoplasia grade 2 had a lower risk for progression to cervical intraepithelial neoplasia grade 3 or worse during 28 months of follow-up when compared with women who were not vaccinated but only if the vaccine was administered by the age of 20 years. These findings may suggest that the human papillomavirus vaccination status can be used for risk stratification in clinical management of cervical intraepithelial neoplasia grade 2.

Incidence of anogenital warts after the introduction of the quadrivalent HPV vaccine program in Manitoba, Canada

Background

The incidence of anogenital warts (AGW) decreased after the introduction of the quadrivalent human papillomavirus (qHPV) vaccine in multiple jurisdictions. We studied how comparing AGW incidence rates with different outcomes affects the interpretation of the qHPV vaccination program. To do this, we replicated multiple study designs within a single jurisdiction (Manitoba).

Methods

We measured the incidence rates of AGW, AGW-related prescriptions, chlamydia, and gonorrhea (the latter two as sham outcomes) between 2001 and 2017 using several clinical and administrative health databases from Manitoba. We then used incidence rate ratios (IRRs) to compare, for each outcome, the rate for the 1997–1998 birth cohort (the first cohorts eligible for the publicly funded qHPV vaccination program) and the older 1995–1996 birth cohort.

Results

AGW incidence in Manitoba dropped 72% (95% confidence interval 54–83%) among 16–18 year-old girls and 51% (14–72%) among boys after the introduction of the female-only qHPV vaccination program. Trends in AGW-related prescriptions were different from trends in AGW diagnoses as these prescriptions peaked shortly after the introduction of the publicly funded qHPV vaccine program. Chlamydia and gonorrhea incidence rates also decreased 12% (5–18%) and 16% (-1-30%), respectively, for 16–18 year-old girls.

Conclusions

The publicly funded school-based qHPV vaccine program reduced AGW incidence in Manitoba by three-quarters in young females. AGW-related prescriptions are a poor proxy for medically attended AGW after the introduction of the publicly funded qHPV vaccination program. Different sexual habits in adolescents are, at most, responsible for a small portion of the reduction in AGW incidence.

Introduction to Regression Discontinuity Design

It is common clinical practice for physicians to refer to specific diagnostic criteria for day-to-day decision-making. In particular, whether or not to provide a particular treatment is often determined by the cutoff value of a relevant diagnostic marker. Regression discontinuity design (RDD) is a method for evaluating scenarios where intervention is determined by the certain cutoff value (e.g., threshold) of a continuous variable. RDD represents a powerful method for assessing intervention effects and outcomes. RDD is underutilized in clinical research and there are many opportunities to apply RDD in this setting. This article introduces the principles of RDD and provides examples of clinical studies that have used this design.

HPV vaccination among seropositive, DNA negative cohorts: a systematic review & meta-analysis

Objective

Vaccine efficacy among previously exposed, but currently uninfected women, i.e., those who have serological evidence of a prior human papillomavirus (HPV) infection without corresponding detectable HPV DNA, remains incompletely defined. This meta-analysis assessed the serotype-specific efficacy of prophylactic HPV vaccination against HPV16/18 persistent infection (PI) and cervical intraepithelial neoplasia (CIN) among seropositive, DNA negative (SPDN) women enrolled to randomized controlled trials (RCTs) of HPV L1-based vaccines.

Methods

Searches were conducted on 08/16/20 on MEDLINE, Embase, Scopus and CENTRAL. RCTs of L1-based prophylactic bivalent or quadrivalent HPV vaccines, reporting serotype-specific clinical efficacy endpoints in the HPV16/18 seropositive, DNA-negative populations were included. Relative risks (RRs) of 6-month PI (6mPI), 12-month PI (12mPI), CIN1+ and CIN2+ were pooled using a random-effects model.

Results

A total of 1,727 citations were reviewed. 8 studies, with a total of 9,569 SPDN participants, met all eligibility criteria. The RR of 6mPI (RR=0.22; 95% confidence interval [CI]=0.08–0.61; p=0.018), 12mPI (RR=0.20; 95% CI=0.05–0.80; p=0.035), CIN1+ (RR=0.13; 95% CI=0.05–0.30; p=0.003) and CIN2+ (RR=0.15; 95% CI=0.04–0.59; p=0.022) was significantly reduced in the vaccinated compared to the unvaccinated group.

Conclusion

Our findings suggest high serotype-specific efficacy for HPV vaccination among cohorts of women with evidence of prior HPV16/18 infections, including 87% efficacy (95% CI=70%–95%; p=0.003) against HPV16/18 cervical dysplasia. HPV vaccination is highly effective among uninfected women, regardless of prior exposure history.

Trial Registration

PROSPERO Identifier: CRD42020206888

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.

Using observational epidemiology to evaluate COVID-19 vaccines: integrating traditional methods with new data sources and tools

Although clinical trials are necessary for vaccine approval, observational epidemiology will be required to evaluate the long-term effectiveness, safety, and population impacts of newly approved COVID-19 vaccines under real-world field conditions. In this commentary, I argue that a hybrid approach that combines new data sources and tools, including COVID-19 vaccine registries, with traditional epidemiological methods will be needed to evaluate COVID-19 vaccines using observational epidemiology. Wherever possible, primary data collection, active surveillance, and linkage with existing population-based cohorts should be leveraged to supplement secondary data sources and passive surveillance systems. Evidence-informed public health decision making around provincial COVID-19 immunization programs will need to account for potential biases, incomplete or conflicting information, and heterogeneity across subpopulations.

Are We Facing a New Colposcopic Practice in the HPV Vaccination Era? Opportunities, Challenges, and New Perspectives

The combination of primary and secondary prevention has already influenced the colposcopic practice by reduction in HPV (human papillomavirus) vaccine-type HSIL (HIGH-GRADE SIL), colposcopy referral numbers, colposcopic positive predictive value (PPV) for CIN2+, and by modification of referral pattern, colposcopic performance, and procedures. Different strategies, both isolated and combined, have been proposed in order to maintain the diagnostic accuracy of colposcopy: patient risk stratification based on immediate or future risk of CIN3+ or on HPV genotyping after a positive screening test. Data are needed to support alternative colposcopic strategies based on vaccination status and on the application of artificial intelligence where the patient's risk stratification is implicit in precision medicine which involves the transition from an operator-dependent morphology-based to a less-operator dependent, more biomolecular management. The patient's risk stratification based on any combination of "history" and "test results" to decrease colposcopy workload further reduce colposcopic and histologic morphological approaches, while adding genotyping to the risk stratification paradigm means less cytologic morphologic diagnosis. In Italy, there is a strong colposcopic tradition and there is currently no immediate need to reduce the number of colposcopies. Instead, there is a need for more accredited colposcopists to maintain the diagnostic accuracy of colposcopy in the vaccination era.

The impact of a universal human papilloma virus (HPV) vaccination program on lower genital tract dysplasia and genital warts

Assess Ontario's school-based human papillomavirus (HPV) vaccination program on reducing rates of cervical dysplasia, colposcopy services and treatment for genital warts, cervical conization, cryotherapy and laser vaporization of the lower genital tract. Women born in 1995 in Ontario, Canada were the first cohort of students to receive the vaccine. We followed these women from age 18-23 and identified pap test cytology results, referral and attendance at colposcopy, treatment of HPV related warts and treatment of lower-genital tract dysplasia using administrative databases. We compared the incidence of these outcomes to women born in 1985, followed during the same age period prior to access to the HPV vaccine. We calculated relative risk ratios for all outcomes over the 5-year period for the unvaccinated group compared to the vaccinated group. Results were stratified at the income and geographic level. A total of 221,039 women were included. Among vaccinated women, 5.2% percent had cytologic abnormalities and 2.7% required treatment for pre-invasive disease or warts compared to 9.2% and 5.2%, respectively among unvaccinated women. The relative risk of developing a low-grade cytologic abnormality if unvaccinated was 1.69 and 3.74 for high-grade abnormalities. The relative risk of requiring colposcopy if unvaccinated was 1.94 and they were 6.15 times more likely to require treatment. There were no differences between socio-economic groups and geographic regions. Vaccination programs are effective at decreasing rates of cervical dysplasia, lead to reduced need for colposcopy, treatment of HPV related warts and pre-invasive disease even at early ages.

School-entry requirements for HPV vaccination: part of the patchwork for HPV-related cancer prevention

Human papillomavirus (HPV) vaccination can prevent six types of HPV-related cancers, and approximately, 54.2% of adolescents are up-to-date with the HPV vaccine in the United States. While moderate success has been achieved with provider- and parent-focused interventions, HPV vaccination in the U.S. lags well behind desired goals. In order to maximize HPV vaccination and prevention of HPV-related cancers, it may be prudent to consider state policy approaches, such as school-entry requirements as part of the patchwork of provider, parent, and structural interventions. In this paper, we reviewed the history of efforts to implement school-entry requirements for HPV vaccine, the challenges and benefits associated with implementing these requirements, and the evidence for the effectiveness of school-entry requirements. In addition, we presented new data from Rhode Island's Immunization Information System (IIS) showing how their school-entry requirement, implemented in 2015, has impacted HPV vaccination rates. These registry data indicate that HPV vaccination rates improved significantly after the 2014-2015 school year and policy implementation, and add to the ongoing evidence supporting the value of school-entry requirements for HPV vaccination. School-entry requirements should be considered alongside other initiatives and policies for promoting HPV vaccine uptake. Taking a comprehensive systems approach to HPV vaccination is needed.

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.

Vaccine Hesitancy and Differential Susceptibility to Media Coverage: A Critical Documentary Led to Substantial Reductions in Human Papillomavirus Vaccine Uptake in Denmark

OBJECTIVES

To investigate whether negative media coverage of the human papillomavirus (HPV) vaccine led to a decrease in the uptake of the first dose of the HPV vaccine (HPV1) in Denmark and, importantly, whether some groups of individuals were more susceptible to negative media coverage.

METHODS

We measured HPV vaccine uptake of 12-year-old girls born in 2001 to 2004 using Danish administrative data. A quasi-experimental design was employed to assess whether a documentary that was critical of the HPV vaccine and aired in March 2015 affected HPV uptake.

RESULTS

The documentary led to a quick and substantial decrease in the monthly propensity to vaccinate, which dropped 3 percentage points-or about 50%-in response to the documentary. Responses differed substantially across subgroups, and girls from families with high socioeconomic status (SES) were more susceptible to the negative media coverage.

CONCLUSIONS

Susceptibility to negative media coverage varied substantially across subgroups, highlighting the need for policy makers to appropriately target and differentiate initiatives to improve vaccine compliance rates.

Age-standardized cancer-incidence trends in Canada, 1971-2015

BACKGROUND

Although cancer incidence over time is well documented in Canada, trends by birth cohort and age group are less well known. We analyzed age- and sex-standardized incidence trends in Canada for 16 major cancer sites and all cancers combined.

METHODS

We obtained nationally representative population-based cancer incidence data in Canada between 1971 and 2015 from the National Cancer Incidence Reporting System (1969-1992) and the Canadian Cancer Registry (1992-2015). We analyzed cancer-incidence trends, reported as annual percent change (APC) for each 10-year group from age 20 to 89 years. We also estimated age-adjusted incidence rate ratios from fitted birth cohort models.

RESULTS

Across most age categories, the most recent trends show significant decreases in the incidence of cervical (APC -8.8% to -0.33%), lung (men: -7.42% to -0.36%; women: -6.27% to 1.07%), bladder (women: -4.12% to -0.07%; men: -5.13% to -0.38%) and prostate cancer (-11.11% to -1.11%). Significant increasing trends were observed for kidney, thyroid and uterine cancers. Overall incidence has increased among both sexes younger than 50 years of age, with recent increases in pancreatic cancer among men, breast cancer among women and colorectal cancer among both sexes. From the birth cohort analysis, we observed increasing trends in colorectal, liver and prostate cancers among men; kidney cancer and melanoma among women; and thyroid cancer among both sexes. We observed decreasing trends in cervical and ovarian cancers, and in bladder and lung cancers among men.

INTERPRETATION

Cancer incidence is decreasing at many sites targeted by primary-prevention efforts, such as smoking cessation and screening programs. Substantial increases in incidence among younger populations are driven by cancers possibly associated with obesity.

Effectiveness of school-based and high-risk human papillomavirus vaccination programs against cervical dysplasia in Manitoba, Canada

The effectiveness of a vaccination program is influenced by its design and implementation details and by the target population characteristics. Using routinely collected population-based individual-level data, we assessed the effectiveness (against cervical dysplasia) of Manitoba's quadrivalent human papillomavirus (qHPV) routine school-based vaccination program and a short-lived campaign that targeted women at high-risk of developing cervical cancer. Females ≥9 years old who received the qHPV vaccine in Manitoba (Canada) between September 1, 2006, and March 31, 2013 (N = 31,442) were matched on age and area of residence to up to three unvaccinated females. Cox proportional hazards models were used to estimate qHPV VE against high-grade (HSILs) and low-grade squamous intraepithelial lesions (LSILs) and atypical squamous cells of undetermined significance (ASCUS). Among 14-17-year-old participants who had Pap cytology after enrollment, the adjusted qHPV VE estimates were 30% (17-58%) and 36% (21-48%) against the detection of HSILs and LSILs, respectively. There was, however, no evidence of program effectiveness among females vaccinated at ≥18 years of age and among those with a history of abnormal cytology, who were mostly vaccinated as part of the high-risk program. Estimates of VE for females vaccinated in the school-based program are consistent with the expected benefits from qHPV vaccination. No similar benefits were detected among women vaccinated at an older age, and those with abnormal cytology, who were targeted by the high-risk program. Further efforts should be targeted at achieving higher vaccine coverage among preadolescents, prior to the initiation of sexual activity.

Evaluating the Effectiveness of Vaccines Using a Regression Discontinuity Design

The regression discontinuity design (RDD), first proposed in the educational psychology literature and popularized in econometrics in the 1960s, has only recently been applied to epidemiologic research. A critical aim of infectious disease epidemiologists and global health researchers is to evaluate disease prevention and control strategies, including the impact of vaccines and vaccination programs. RDDs have very rarely been used in this context. This quasi-experimental approach using observational data is designed to quantify the effect of an intervention when eligibility for the intervention is based on a defined cutoff such as age or grade in school, making it ideally suited to estimating vaccine effects given that many vaccination programs and mass-vaccination campaigns define eligibility in this way. Here, we describe key features of RDDs in general, then specific scenarios, with examples, to illustrate that RDDs are an important tool for advancing our understanding of vaccine effects. We argue that epidemiologic researchers should consider RDDs when evaluating interventions designed to prevent and control diseases. This approach can address a wide range of research questions, especially those for which randomized clinical trials would present major challenges or be infeasible. Finally, we propose specific ways in which RDDs could advance future vaccine research.

Small size, big impact: how studies of small DNA tumour viruses revolutionized biology

Intense study of three families of small tumour viruses with double-stranded DNA genomes, carried out over 50 years, has had a profound impact on biology. The polyomaviruses and papillomaviruses have circular DNA genomes of approximately 5000 and approximately 8000 base-pairs, respectively, and thus encode only a handful of proteins. Adenoviruses have a 32 000-base-pair linear DNA genome, still far smaller than the three billion-base-pair human genome. Members of all three virus families can transform cultured cells to tumorigenicity and cause tumours in experimental animals. Several human papillomaviruses (HPV) and at least one polyomavirus are oncogenic in humans. Early analysis of these viruses, particularly the polyomavirus SV40, led to the development of many powerful experimental tools, including restriction mapping, site-directed mutagenesis, gene transfer, genome-wide sequencing and recombinant DNA. These tools have since been refined and used to study cellular genes, revolutionizing our understanding of biology. These tools were also applied to the viruses themselves. Analysis of the virus life cycle and the effect of these viruses on cells yielded important new insights into many aspects of gene expression, DNA replication, cell biology and carcinogenesis. These studies have also led to vaccination strategies to prevent infection and cancer in humans. This article is part of the theme issue 'Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses'.

Prevalence of cervical disease at age 20 after immunisation with bivalent HPV vaccine at age 12-13 in Scotland: retrospective population study

OBJECTIVE

To quantify the effect on cervical disease at age 20 years of immunisation with bivalent human papillomavirus (HPV) vaccine at age 12-13 years.

DESIGN

Retrospective population study, 1988-96.

SETTING

National vaccination and cervical screening programmes in Scotland.

PARTICIPANTS

138 692 women born between 1 January 1988 and 5 June 1996 and who had a smear test result recorded at age 20.

MAIN OUTCOME MEASURES

Effect of vaccination on cytology results and associated histological diagnoses from first year of screening (while aged 20), calculated using logistic regression.

RESULTS

138 692 records were retrieved. Compared with unvaccinated women born in 1988, vaccinated women born in 1995 and 1996 showed an 89% reduction (95% confidence interval 81% to 94%) in prevalent cervical intraepithelial neoplasia (CIN) grade 3 or worse (from 0.59% (0.48% to 0.71%) to 0.06% (0.04% to 0.11%)), an 88% reduction (83% to 92%) in CIN grade 2 or worse (from 1.44% (1.28% to 1.63%) to 0.17% (0.12% to 0.24%)), and a 79% reduction (69% to 86%) in CIN grade 1 (from 0.69% (0.58% to 0.63%) to 0.15% (0.10% to 0.21%)). Younger age at immunisation was associated with increasing vaccine effectiveness: 86% (75% to 92%) for CIN grade 3 or worse for women vaccinated at age 12-13 compared with 51% (28% to 66%) for women vaccinated at age 17. Evidence of herd protection against high grade cervical disease was found in unvaccinated girls in the 1995 and 1996 cohorts.

CONCLUSIONS

Routine vaccination of girls aged 12-13 years with the bivalent HPV vaccine in Scotland has led to a dramatic reduction in preinvasive cervical disease. Evidence of clinically relevant herd protection is apparent in unvaccinated women. These data are consistent with the reduced prevalence of high risk HPV in Scotland. The bivalent vaccine is confirmed as being highly effective vaccine and should greatly reduce the incidence of cervical cancer. The findings will need to be considered by cervical cancer prevention programmes worldwide.

HPV Vaccine in Adolescents

Human papillomavirus (HPV), the most common sexually transmitted viral infection worldwide, is the causative agent for cervical cancer and attributed to anogenital cancers as well as oropharyngeal cancer. Three effective, safe, prophylactic HPV vaccines have been licensed, and studies have demonstrated decreases in HPV prevalence and HPV-related disease endpoints without evidence of waning protection to date. In the United States, only the 9-valent vaccine, which covers 90% of the cancers attributed to HPV in US registries, is available. Because higher titers are found at younger ages, two rather than three doses are needed if the first dose is given prior to age 15 years. HPV vaccination rates in the US lag compared to tetanus-diptheria-acellular pertussis and meningococcal conjugate vaccines. Current efforts are aimed at improving vaccination rates through delivering strong and consistent clinician recommendations at the same time as discussing other adolescent vaccines and preventing missed opportunities for vaccination. [Pediatr Ann. 2019;48(2):e71-e77.].

Antiretroviral Therapy and Mortality in Rural South Africa: A Comparison of Causal Modeling Approaches

Estimation of causal effects from observational data is a primary goal of epidemiology. The use of multiple methods with different assumptions relating to exchangeability improves causal inference by demonstrating robustness across assumptions. We estimated the effect of antiretroviral therapy (ART) on mortality in rural KwaZulu-Natal, South Africa, from 2007 to 2011, using 2 methods with substantially different assumptions: the regression discontinuity design (RDD) and inverse-probability–weighted (IPW) marginal structural models (MSMs). The RDD analysis took advantage of a CD4-cell-count–based threshold for ART initiation (200 cells/μL). The 2 methods yielded consistent but nonidentical results for the effect of immediate initiation of ART (RDD intention-to-treat hazard ratio (HR) = 0.66, 95% confidence interval (CI): 0.35, 1.26; RDD complier average causal effect HR = 0.56, 95% CI: 0.41, 0.77; IPW MSM HR = 0.49, 95% CI: 0.42, 0.58). Although RDD and IPW MSM estimates have distinct identifying assumptions, strengths, and limitations in terms of internal and external validity, results in this application were similar. The differences in modeling approaches and the external validity of each method may explain the minor differences in effect estimates. The overall consistency of the results lends support for causal inference about the effect of ART on mortality from these data.

Regression Discontinuity and Randomized Controlled Trial Estimates: An Application to The Mycotic Ulcer Treatment Trials

PURPOSE

We compare results from regression discontinuity (RD) analysis to primary results of a randomized controlled trial (RCT) utilizing data from two contemporaneous RCTs for treatment of fungal corneal ulcers.

METHODS

Patients were enrolled in the Mycotic Ulcer Treatment Trials I and II (MUTT I & MUTT II) based on baseline visual acuity: patients with acuity ≤ 20/400 (logMAR 1.3) enrolled in MUTT I, and >20/400 in MUTT II. MUTT I investigated the effect of topical natamycin versus voriconazole on best spectacle-corrected visual acuity. MUTT II investigated the effect of topical voriconazole plus placebo versus topical voriconazole plus oral voriconazole. We compared the RD estimate (natamycin arm of MUTT I [N = 162] versus placebo arm of MUTT II [N = 54]) to the RCT estimate from MUTT I (topical natamycin [N = 162] versus topical voriconazole [N = 161]).

RESULTS

In the RD, patients receiving natamycin had mean improvement of 4-lines of visual acuity at 3 months (logMAR -0.39, 95% CI: -0.61, -0.17) compared to topical voriconazole plus placebo, and 2-lines in the RCT (logMAR -0.18, 95% CI: -0.30, -0.05) compared to topical voriconazole.

CONCLUSIONS

The RD and RCT estimates were similar, although the RD design overestimated effects compared to the RCT.

Quadrivalent human papillomavirus vaccination in girls and the risk of autoimmune disorders: the Ontario Grade 8 HPV Vaccine Cohort Study

BACKGROUND

Despite demonstrated effectiveness in real-world settings, concerns persist regarding the safety of the quadrivalent human papillomavirus (HPV4) vaccine. We sought to assess the risk of autoimmune disorders following HPV4 vaccination among grade 8 girls eligible for Ontario's school-based HPV vaccination program.

METHODS

We undertook a population-based retrospective cohort study using Ontario's administrative health and vaccination databases from 2007 to 2013. The self-controlled case series method was used to compare the rate of a composite end point of autoimmune disorders diagnosed during days 7-60 post-vaccination ("exposed" follow-up) to that at any other time ("unexposed"). The analysis was repeated to assess the effect of a history of immune-mediated diseases and time since vaccination. We also conducted an exploratory analysis of individual autoimmune disorders. Rate ratios and 95% confidence intervals (CIs) were estimated using conditional Poisson regression, adjusted for age, seasonality, concomitant vaccinations and infections.

RESULTS

The study cohort consisted of 290 939 girls aged 12-17 years who were eligible for vaccination between 2007 and 2013. There was no significant risk for developing an autoimmune disorder following HPV4 vaccination (n = 681; rate ratio 1.12, 95% CI 0.85-1.47), and the association was unchanged by a history of immune-mediated disorders and time since vaccination. Exploratory analyses of individual autoimmune disorders found no significant risks, including for Bell palsy (n = 65; rate ratio 1.73, 95% CI 0.77-3.89), optic neuritis (n = 67; rate ratio 1.57, 95% CI 0.74-3.33) and Graves disease (n = 47; rate ratio 1.55, 95% CI 0.92-2.63).

INTERPRETATION

We did not observe an increased risk of autoimmune disorders following HPV4 vaccination among teenaged girls. These findings should reassure parents and health care providers.

Awareness and Knowledge Levels of Turkish College Students about Human Papilloma Virus Infection and Vaccine Acceptance

Awareness of HPV by the target population is an important determinant of vaccine acceptance. The aim of this study is to evaluate the awareness of HPV infection and acceptability of the HPV vaccines among Turkish college students. College students aged 18-30 who were attending a large public university in Ankara participated in this study. The participants were asked to complete a questionnaire to elicit demographic characteristics, awareness level of HPV and HPV vaccine, and willingness to be vaccinated. One thousand one hundred sixty students responded to the invitation email and completed the questionnaire. The mean scores of female students about HPV and HPV vaccine were 7.1/15 and 3.6/9, respectively, while these scores were 7.9/15 and 3.4/9 among male students, respectively. While 51 % percent of female and 33.5 % of male students had heard of HPV and 32.8 % and 18 % of them had heard of HPV vaccine, respectively, only 1.5 % of female and 0.4 % of male students had been vaccinated against HPV. A total of 507 students (43.7 %) had previously heard of HPV. Only 309 (26.6 %) of the participants had previously heard of the HPV vaccine, and 45.1 % of the students were willing to receive HPV vaccination. The main predictors for willingness to be vaccinated were the following: sexual experience, sexual behavior, past history of sexually transmitted infection (STI), and knowledge about HPV and HPV vaccine. Higher awareness levels of HPV and HPV vaccine are significantly related to greater willingness to be vaccinated, and the main reasons for rejecting the vaccine were insufficient information about the vaccine and possible unknown side effects.

Impact of early antiretroviral therapy eligibility on HIV acquisition: household-level evidence from rural South Africa

Objectives:

We investigate the effect of immediate antiretroviral therapy (ART) eligibility on HIV incidence among HIV-uninfected household members.

Design:

Regression discontinuity study arising from a population-based cohort.

Methods:

Household members of patients seeking care at the Hlabisa HIV Treatment and Care Programme in rural KwaZulu-Natal South Africa between January 2007 and August 2011 with CD4⁺ cell counts up to 350 cells/μl were eligible for inclusion if they had at least two HIV tests and were HIV-uninfected at the time the index patient linked to care (N = 4115). Regression discontinuity was used to assess the intention-to-treat effect of immediate versus delayed ART eligibility on HIV incidence among household members. Exploiting the CD4⁺ cell count-based threshold rule for ART initiation (CD4⁺ < 200 cells/μl until August 2011), we used Cox proportional hazards models to compare outcomes for household members of patients who presented for care with CD4⁺ cell counts just above versus just below the ART initiation threshold.

Results:

Characteristics of household members of index patients initiating HIV care were balanced between those with an index patient immediately eligible for ART (N = 2489) versus delayed for ART (N = 1626). There were 337 incident HIV infections among household members, corresponding to an HIV incidence of 2.4 infections per 100 person-years (95% confidence interval 2.5–3.1). Immediate eligibility for treatment reduced HIV incidence in households by 47% in our optimal estimate (hazard ratio = 0.53, 95% confidence interval 0.30–0.96), and by 32–60% in alternate specifications of the model.

Conclusion:

Immediate eligibility of ART led to substantial reductions in household-level HIV incidence.

Colposcopy at a turning point

For women who have abnormal Pap test results, the biopsy under colposcopic evaluation is the gold standard for determining the treatment modality. To increase the effectiveness of colposcopic communication, the International Federation for Cervical Pathology and Colposcopy (IFCPC) recently published fourth new nomenclature, aiming to create an evidence-based terminology. To increase the diagnostic accuracy of colposcopy, multiple biopsies of two or more sites are recommended. Recently, with the introduction of human papillomavirus (HPV) vaccine for cervical cancer prevention, pre-cancerous diseases caused by virus types 16 and 18 have been reduced, which is expected to reduce the number of colposcopic examinations and make colposcopic diagnosis more difficult.

4-Valent Human Papillomavirus (4vHPV) Vaccine in Preadolescents and Adolescents After 10 Years

OBJECTIVES

We describe the final 10-year data for the long-term follow-up study of the 4-valent human papillomavirus (4vHPV) vaccine in preadolescents and adolescents.

METHODS

In the base study (V501-018), 1661 sexually inactive boys and girls received the 4vHPV vaccine (early vaccination group [EVG], managed for 9.9 years) or a placebo at day 1, month 2, and month 6. Thereafter, at month 30, the placebo group (catch-up vaccination group [CVG], managed for 7.4 years) received the 4vHPV vaccine by using the same dosing schedule. Long-term anti-HPV type 6, 11, 16, and 18 immune responses were assessed. Effectiveness was estimated by calculating the incidence rate of the primary endpoints (HPV types 6, 11, 16, and 18-related disease or persistent infection).

RESULTS

For HPV types 6, 11, and 16, 89% to 96% of subjects remained seropositive through 10-years postvaccination. The preadolescents had 38% to 65% higher geometric mean titers at month 7, which remained 16% to 42% higher at 10 years compared with adolescents. No cases of HPV type 6, 11, 16, and 18-related diseases were observed. Ten subjects had a persistent infection of ≥6 months duration with vaccine-type HPV and 2 subjects had persistent infection for ≥12 months. No new serious adverse events were reported through 10 years.

CONCLUSIONS

A 3-dose regimen of the 4vHPV vaccine was immunogenic, clinically effective, and generally well tolerated in preadolescents and adolescents during 10 years of follow-up. These long-term findings support efforts to vaccinate this population against HPV before exposure.

Missed Opportunities for Human Papillomavirus Vaccine Initiation in an Insured Adolescent Female Population

BACKGROUND

This study assessed the initiation of HPV vaccination in insured adolescent females in relation to physician visits and receipt of other vaccines routinely given at the same age.

METHODS

January 1, 2010, and September 31, 2015. Vaccination administration was determined by using Current Procedural Terminology codes. A missed opportunity was defined as the absence of an HPV vaccine at the following encounter types: visits with a 4-valent meningococcal conjugate vaccine (MenACWY) or tetanus, diphtheria, and acellular pertussis (Tdap) vaccine claim; well adolescent visits; or any encounter with a primary care provider (PCP). Missed opportunities were stratified by type of provider (pediatrician or nonpediatrician).

RESULTS

Among 14588 adolescent girls, only 6098 (41.8%) initiated the HPV vaccine series. HPV vaccine was given at 37.1% of visits when a Tdap or MenACWY vaccine was administered, 26.0% of well adolescent visits and 41.8% of PCP visits. Pediatricians had fewer missed opportunities than nonpediatricians to administer HPV (50.7% vs 60.8%), as well as Tdap, although the difference was larger for Tdap (7.0% vs 29.6%).

CONCLUSIONS

These data indicate that pediatricians and nonpediatricians alike are missing opportunities to administer the HPV vaccine when other adolescent vaccines are given. Efforts should be focused on converting these missed vaccination opportunities into cancer-prevention visits.

The early impact of human papillomavirus vaccination on anogenital warts in Québec, Canada

In Québec province in Canada, a public school-based and catch-up HPV vaccination programs with the quadrivalent vaccine have been introduced in September 2008 for girls aged 9-17 years. We assessed the early impact of the HPV vaccination program on the incidence of anogenital warts (AGW) in the Quebec general population. We used the provincial health administrative data of the Régie de l'assurance maladie du Québec (RAMQ). AGW were identified either through a prescription of podofilox, or a medical procedure code specific to AGW, or a diagnostic code for viral warts followed by a prescription of imiquimod or fluorouracil. Sex- and age-specific incidence rates were calculated for pre-vaccination (2004-2007) and vaccination (2009-2012) periods. We found a significant decline of 45% and 19% in the incidence of AGWs among females aged 15-19 and 20-24 years, respectively. A decline of 21% was also seen among males aged 15-19 years. The median age at an episode of AGW increased from 27 years in 2004 to 31 years in 2012 among females and remained stable in males. Our findings indicate that the HPV public vaccination program is associated with an important reduction in the incidence of AGW among young females and males. The benefit is more pronounced among females 15-19 years of age, who were eligible for the public vaccination program. The observed decline among young males could be due to herd immunity and/or privately paid vaccination.

Maternal and Infant Outcomes After Human Papillomavirus Vaccination in the Periconceptional Period or During Pregnancy

OBJECTIVE

To evaluate whether quadrivalent human papillomavirus vaccine (4vHPV) administered during the periconceptional period or during pregnancy was associated with increased risks for adverse obstetric events, adverse birth outcomes, or selected major structural birth defects.

METHODS

We conducted a retrospective, observational cohort study using administrative and health care data from the Vaccine Safety Datalink. Insured women 13-27 years old with singleton pregnancies and a live birth from January 1, 2007, through September 1, 2013, who received 4vHPV during the periconceptional period (2 weeks before to 2 weeks after their last menstrual period), during pregnancy, or during both periods combined were compared with women who had a live birth during the same time period and received 4vHPV 4-18 months before their last menstrual period. We examined risks of gestational diabetes, hypertensive disorders of pregnancy, chorioamnionitis, preterm birth, small-for-gestational-age birth, and selected major structural birth defects in offspring. We estimated relative risks associated with receipt of 4vHPV during the periconceptional period, during pregnancy, and both exposure periods combined using a generalized linear model with Poisson distribution including a propensity score that included relevant maternal demographic and pregnancy characteristics.

RESULTS

Of 92,579 potentially eligible pregnant women, 720 received 4vHPV during the periconceptional period, 638 received 4vHPV during pregnancy, and 8,196 received 4vHPV during the comparison period. Administration of 4vHPV during pregnancy was not associated with increased risk of adverse obstetric events, birth outcomes. Preterm birth occurred in 7.9% of pregnancies with vaccine exposures during pregnancy compared with 7.6% of pregnancies with vaccination in the comparison period (adjusted relative risk 0.97, 95% CI 0.72-1.3). Major structural birth defects were diagnosed in 2.0% of pregnancies with vaccine exposure during pregnancy compared with 1.8% of pregnancies with vaccine exposure during the comparison period (adjusted prevalence ratio 1.0, 95% CI 0.52-1.9). Results were similar for 4vHPV exposure during the periconceptional period.

CONCLUSION

Quadrivalent HPV vaccine inadvertently administered in pregnancy or during the periconceptional period was not associated with adverse pregnancy or birth outcomes.

Strategies for evaluating the assumptions of the regression discontinuity design: a case study using a human papillomavirus vaccination programme

Background

The regression discontinuity design (RDD) is a quasi-experimental approach used to avoid confounding bias in the assessment of new policies and interventions. It is applied specifically in situations where individuals are assigned to a policy/intervention based on whether they are above or below a pre-specified cut-off on a continuously measured variable, such as birth date, income or weight. The strength of the design is that, provided individuals do not manipulate the value of this variable, assignment to the policy/intervention is considered as good as random for individuals close to the cut-off. Despite its popularity in fields like economics, the RDD remains relatively unknown in epidemiology where its application could be tremendously useful.

Methods

In this paper, we provide a practical introduction to the RDD for health researchers, describe four empirically testable assumptions of the design and offer strategies that can be used to assess whether these assumptions are met in a given study. For illustrative purposes, we implement these strategies to assess whether the RDD is appropriate for a study of the impact of human papillomavirus vaccination on cervical dysplasia.

Results

We found that, whereas the assumptions of the RDD were generally satisfied in our study context, birth timing had the potential to confound our effect estimate in an unexpected way and therefore needed to be taken into account in the analysis.

Conclusions

Our findings underscore the importance of assessing the validity of the assumptions of this design, testing them when possible and making adjustments as necessary to support valid causal inference.

Development of a cross-cultural HPV community engagement model within Scotland

OBJECTIVE

To examine cultural barriers and participant solutions regarding acceptance and uptake of the human papillomavirus (HPV) vaccine from the perspective of Black African, White-Caribbean, Arab, Indian, Bangladeshi and Pakistani young people.

METHODS

In total, 40 young people from minority ethnic communities in Scotland took part in a qualitative study, involving seven focus groups and four paired interviews, to explore their views and experiences of the HPV vaccine. Using critical discursive psychology, the analysis focused on young people's accounts of barriers and enablers to information, access and uptake of the HPV vaccination programme.

RESULTS

Participants suggested innovative strategies to tackle intergenerational concerns, information design and accessibility, and public health communications across diverse contexts. A cross-cultural community engagement model was developed, embracing diversity and contradiction across different ethnic groups. This included four inter-related strategies: providing targeted and flexible information for young people, vaccine provision across the life-course, intergenerational information and specific cross-cultural communications.

CONCLUSION

This is the first HPV cross-cultural model inductively derived from accounts of young people from different ethnic communities. We recommend public health practitioners and policymakers consider using the processes and strategies within this model to increase dialogue around public engagement, awareness and receptivity towards HPV vaccination.

Effectiveness of HPV vaccines against genital warts in women from Valencia, Spain

OBJECTIVES

To assess the effectiveness of the HPV vaccines in preventing genital warts in young women.

DESIGN

Population-based study using health databases.

SETTING

Valencian Community (Spain).

PARTICIPANTS

All girls and women aged 14-19years who were registered in the Valencian Community between January 2009 and December 2014 (n=279,787).

MAIN OUTCOME MEASURES

Incident cases of genital warts were defined as the first activation of diagnosis code ICD-9-CM 078.11 (Condyloma acuminatum) in primary care and outpatient clinics during the study period.

RESULTS

There were 612 cases of genital warts. The overall incidence rate was 75.8/100,000 person-years (95% CrI 69.7-81.8). There was a decrease in genital warts when female candidates to be vaccinated with quadrivalent HPV vaccine reached the age of 18 (in 2012), compared to previous years. Incidence of genital warts in unvaccinated women and those who received the bivalent vaccine was higher than in girls and women who received the quadrivalent HPV vaccine. The effectiveness of a three-dose regimen of the quadrivalent HPV vaccine was 77% (95 CrI: 66-85%), whereas that of a single dose was 61% (95 CrI: 20-87%). No effectiveness was seen with a full vaccination course with the bivalent HPV vaccine.

CONCLUSIONS

Three doses of the quadrivalent HPV vaccine were effective against genital warts in our population. Moreover, with low vaccine coverage the incidence of genital warts decreased only in the vaccinated.

HPV vaccination initiation after the routine-recommended ages of 11-12 in the United States

BACKGROUND

Since 2006, routine HPV vaccination has been recommended for females aged 11-12 in the US. However not much is known about the extent of and factors associated with HPV vaccination after the ages of 11-12.

METHODS

Provider-verified data on 8,710 females aged 13-17 were analyzed from the 2013 NIS-Teen survey. 2013 data was utilized since it was the first year one can fully evaluate the age at vaccination through age 17 for females who could receive the HPV vaccine at age 11.

RESULTS

Among HPV vaccinated females who were 17 in 2013, 47% (95%CI=43%-50%) received their first dose after age 12, and 24% (95%CI=21%-26%) received their first dose after age 14. The HPV vaccine was more likely to be initiated later than the meningococcal and Tdap vaccines (p<0.05), and later HPV vaccine initiation was more common among those having a more highly educated mother and those not receiving a check-up/well visit between the ages of 11 and 12 in adjusted analyses (p-values<0.05). Females initiating the HPV vaccine late were more likely to not receive three doses (RR=1.90, 95%CI=1.76-2.04).

CONCLUSIONS

HPV vaccination is commonly initiated after the age of 12 in the US, which could limit the vaccine's population-level effectiveness.

Epigenetic Treatment of Persistent Viral Infections

Preclinical Research Approximately 2,500 years ago, Hippocrates used the word herpes as a medical term to describe lesions that appeared to creep or crawl on the skin, advocating heat as a possible treatment. During the last 50 years, pharmaceutical research has made great strides, and therapeutic options have expanded to include small molecule antiviral agents, protease inhibitors, preventive vaccines for a handful of the papillomaviruses, and even cures for hepatitis C virus infections. However, effective treatments for persistent and recurrent viral infections, particularly the highly prevalent herpesviruses, continue to represent a significant unmet medical need, affecting the majority of the world's population. Exploring the population diversity of the human microbiome and the effects its compositional variances have on the immune system, health, and disease are the subjects of intense investigational research and study. Among the collection of viruses, bacteria, fungi, and single-cell eukaryotes that comprise the human microbiome, the virome has been grossly understudied relative to the influence it exerts on human pathophysiology, much as mitochondria have until recently failed to receive the attention they deserve, given their critical biomedical importance. Fortunately, cellular epigenetic machinery offers a wealth of druggable targets for therapeutic intervention in numerous disease indications, including those outlined above. With advances in synthetic biology, engineering our body's commensal microorganisms to seek out and destroy pathogenic species is clearly on the horizon. This is especially the case given recent breakthroughs in genetic manipulation with tools such as the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated) gene-editing platforms. Tying these concepts together with our previous work on the microbiome and neurodegenerative and neuropsychiatric diseases, we suggest that, because mammalian cells respond to a viral infection by triggering a cascade of antiviral innate immune responses governed substantially by the cell's mitochondria, small molecule carnitinoids represent a new class of therapeutics with potential widespread utility against many infectious insults. Drug Dev Res 78 : 24-36, 2017.   © 2016 Wiley Periodicals, Inc.

Risk of Delayed Human Papillomavirus Vaccination in Inner-City Adolescent Women

BACKGROUND

 Uptake of human papillomavirus (HPV) vaccine in the United States is slow, and the effectiveness of the vaccine has not been assessed in high-risk adolescent populations.

METHODS

 We conducted a longitudinal study of 1139 sexually active, inner-city adolescent women receiving the 3-dose quadrivalent (4vHPV) vaccine. Cervical and anal specimens collected semiannually were tested using an L1-specific polymerase chain reaction assay. Postvaccination incidence of 4vHPV vaccine and nonvaccine HPV types, and risk of cervical cytological abnormalities, were assessed in relation to time to completion of all 3 vaccine doses.

RESULTS

 Compared to vaccine naive women at enrollment, vaccinated women had significantly lower incidence rate ratios of cervical infection with HPV6/11/16/18 (0.2; 95% confidence interval [CI], .1-.4) and the related types HPV31 and HPV45 (0.4 [95% CI, .2-1.0] and 0.3 [95% CI, .1-.6], respectively), as well as significantly lower incidence rate ratios of anal infection with HPV6/11/16/18 (0.4; 95% CI, .2-.7). Notably, we observed higher risks of cervical HPV6/11/16/18 infection (hazards ratio [HR], 2.9; 95% CI, 1.0-8.0) and associated cytological abnormalities (HR, 4.5; 95% CI, .7-26.0) among women immunized at ≥15 years of age who took ≥12 months (vs <12 months) to complete the 3-dose regimen.

CONCLUSIONS

 Among adolescents immunized at ≥15 years of age, a longer time to complete the 3-dose schedule was associated with an increased risk of anogenital HPV6/11/16/18 infection and an increased incidence of associated cervical cytological abnormalities.

Effect of human papillomavirus vaccination on cervical cancer screening in Alberta

BACKGROUND

A school-based program with quadrivalent human papillomavirus (HPV) vaccination was implemented in Alberta in 2008. We assessed the impact of this program on Pap test cytology results using databases of province-wide vaccination and cervical cancer screening.

METHODS

We conducted a nested case-control study involving a cohort of women in Alberta born between 1994 and 1997 who had at least 1 Pap test between 2012 and 2015. Women with negative cytology results were controls. Women with low-grade (atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion) and high-grade (atypical squamous cells, cannot rule out a high-grade lesion; or high-grade squamous intraepithelial lesion) cervical abnormalities were cases. Exposure status was assigned according to records of HPV vaccination. Odds ratios (ORs) for abnormal cytology results by vaccination status were adjusted for neighbourhood income, laboratory service, rural versus urban residency, and age.

RESULTS

The total study population was 10 204. Adjusting for age, vaccinated women had a higher screening rate than unvaccinated women (13.0% v. 11.4%, p < 0.001). Among women who received full vaccination (≥ 3 doses), the adjusted OR for cervical abnormalities was 0.72 (95% confidence interval [CI] 0.63-0.82). For high-grade lesions, the adjusted OR was 0.50 (95% CI 0.30-0.85). With 2-dose HPV vaccination, the adjusted OR for cervical abnormalities was 1.08 (95% CI 0.84-1.38).

INTERPRETATION

Quadrivalent HPV vaccination significantly reduced high-grade cervical abnormalities but required 3 doses. Vaccination against HPV was associated with screening uptake. Population-based vaccination and screening programs should work together to optimize cervical cancer prevention.

Early impact of Ontario's human papillomavirus (HPV) vaccination program on anogenital warts (AGWs): A population-based assessment

INTRODUCTION

This study aimed to evaluate the early population impact of Ontario's school-based human papillomavirus (HPV) vaccination program, implemented in September 2007 for grade 8 females, by comparing anogenital wart (AGW) health care utilization before and after vaccine program implementation, in program-eligible and program-ineligible cohorts, focusing on 15-26year olds.

METHODS

Using a retrospective longitudinal population-based study design, health administrative data were used to identify incident AGWs and total health service utilization (HSU) for AGWs for Ontario residents 15years and older between April 1 2004 and March 31 2014. The study period was divided into two eras: the pre-vaccine program era and the vaccine program era. Negative binomial models were generated to analyze trends across time by age group and sex. We adjusted female rates for routine Papanicolaou (Pap) testing to address spillover effects of Pap smear policy changes on AGW diagnosis.

RESULTS

Between fiscal years 2004 and 2013, AGW incidence decreased 2.6% on average per year in 15-17year old females, and total HSU for AGWs decreased an average of 4.8% and 2.2% per year in 15-17 and 18-20year old females. Comparing the vaccine era to the pre-vaccine era, AGW incidence decreased 6.5% in 18-20year old females, and AGW HSU decreased 13.8%, 11.1%, and 10.0% in 15-17, 18-20, and 21-23year old females respectively. In contrast, male AGW incidence rates increased an average of 4.1%, 2.8%, and 0.9% per year in 15-17, 21-23, and 24-26year old males respectively. AGW incidence rates increased 12.2% in 15-17year old males from the pre-vaccine to vaccine era.

CONCLUSION

The decline in AGW incidence and HSU in program-eligible females suggests the school-based HPV vaccination program has had an early population impact in Ontario. The increasing AGW incidence in males suggests no early evidence of herd effects in males.

Regression Discontinuity for Causal Effect Estimation in Epidemiology

Regression discontinuity analyses can generate estimates of the causal effects of an exposure when a continuously measured variable is used to assign the exposure to individuals based on a threshold rule. Individuals just above the threshold are expected to be similar in their distribution of measured and unmeasured baseline covariates to individuals just below the threshold, resulting in exchangeability. At the threshold exchangeability is guaranteed if there is random variation in the continuous assignment variable, e.g., due to random measurement error. Under exchangeability, causal effects can be identified at the threshold. The regression discontinuity intention-to-treat (RD-ITT) effect on an outcome can be estimated as the difference in the outcome between individuals just above (or below) versus just below (or above) the threshold. This effect is analogous to the ITT effect in a randomized controlled trial. Instrumental variable methods can be used to estimate the effect of exposure itself utilizing the threshold as the instrument. We review the recent epidemiologic literature reporting regression discontinuity studies and find that while regression discontinuity designs are beginning to be utilized in a variety of applications in epidemiology, they are still relatively rare, and analytic and reporting practices vary. Regression discontinuity has the potential to greatly contribute to the evidence base in epidemiology, in particular on the real-life and long-term effects and side-effects of medical treatments that are provided based on threshold rules - such as treatments for low birth weight, hypertension or diabetes.

[Epidemiology, prevention and early detection of cervical cancer]

BACKGROUND

Persistent infections with human papillomaviruses are a necessary cause of cervical carcinomas. The development of HPV-based prevention tools, HPV vaccination and HPV testing, is leading to major changes in cervical cancer prevention programs worldwide. A decade after introduction of HPV vaccination in many countries reductions of HPV infections and cancer precursors have been observed in young women. The focus is now on the integration of new approaches for screening of increasingly vaccinated populations.

RESULTS AND CONCLUSIONS

A successful cervical cancer prevention program includes primary screening, triage of screen-positives, and colposcopy-biopsy to identify women with cancer precursors who require treatment. The role of primary screening is to identify a small subset of women with increased risk of cervical precancer, while the majority of women can be reassured that their risk is very low. Depending on the primary screening test, additional triage testing is required to decide who should be referred to colposcopy. Currently, there are three major approaches to cervical cancer screening: Cervical cytology, HPV testing, and HPV-cytology co-testing. Several triage tests for HPV-positive women are currently being evaluated, including cytology, HPV genotyping, p16/Ki-67 cytology and various methylation tests. Due to the increasing number of options for cervical cancer screening, it is challenging to keep screening guidelines current and comprehensible. The increasing complexity can lead to confusion among providers and women who participate in screening programs about the best approaches. Precision prevention is a novel approach to cervical cancer screening that integrates individual medical history with test results for unified, risk-based management decisions.

The effect of mass vaccination campaigns against polio on the utilization of routine immunization services: A regression discontinuity design

BACKGROUND

In most low and middle-income countries (LMIC), vaccines are primarily distributed by routine immunization services (RI) at health facilities. Additional opportunities for vaccination are also provided through mass vaccination campaigns, conducted periodically as part of disease-specific initiatives. It is unclear whether these campaigns are detrimental to RI services, or wether they may stimulate the utilization of RI.

METHODS

Unobserved confounders and reverse causality have limited existing evaluations of the effects of mass vaccination campaigns on RI services. We explored the use of a regression discontinuity design (RDD) to measure these effects more precisely. This is a quasi-experimental method, which exploits random variations in birth dates to identify the causal effects of vaccination campaigns. We applied RDD to survey data on a nationwide vaccination campaign against Polio conducted in Bangladesh.

RESULTS

We compared systematically the children born immediately before vs. after the vaccination campaign. These two groups had similar background characteristics, but differed by their exposure to the vaccination campaign. Contrary to previous studies, exposure to the campaign had positive effects on RI utilization. Children exposed to the campaign received between 0.296 and 0.469 additional doses of DPT vaccine by age 4months than unexposed children.

CONCLUSIONS

RDD constitutes a promising tool to assess the effects of mass vaccination campaigns on RI services. It could be tested in additional settings, using larger and more precise datasets. It could also be extended to measure the effects of other disease-specific interventions on the functioning of health systems, in particular those that occur at a discrete point in time and/or include age-related eligibility criteria.

Human papillomavirus epidemiology and vaccine recommendations: selected review of the recent literature

PURPOSE OF REVIEW

This article provides a clinically relevant review and analysis of the latest research and recommendations regarding human papillomavirus (HPV) vaccine.

RECENT FINDINGS

Although studies have found that bivalent and quadrivalent HPV vaccines are well tolerated and effective, high-risk HPV types not included in these vaccines are responsible for a significant burden of disease worldwide. Clinical trials have found that the recently licensed 9-valent vaccine, which includes five additional high-risk HPV types, is well tolerated and efficacious. This vaccine was added to the Advisory Committee on Immunization Practices HPV vaccination recommendations in 2015. A two-dose series in girls and boys 9-14 years old with a 6- or 12-month interval between doses has been shown to result in antibody titers noninferior to those measured after the three-dose series in women 16-26 years old. The Food and Drug Administration is considering these data.

SUMMARY

Recent publications highlight the safety and effectiveness of HPV vaccines, the licensure of the 9-valent HPV vaccine, and the revision of HPV vaccine recommendations.

Health service utilisation for anogenital warts in Ontario, Canada prior to the human papillomavirus (HPV) vaccine programme introduction: a retrospective longitudinal population-based study

OBJECTIVE

Trends in occurrence of anogenital warts (AGWs) can provide early evidence of human papillomavirus (HPV) vaccination programme impact on preventing HPV infection and HPV-induced lesions. The objective of this study was to provide a baseline of AGW epidemiology in Ontario prior to the introduction of the publicly-funded school-based HPV vaccination programme in September 2007.

SETTING AND PARTICIPANTS

As a retrospective longitudinal population-based study, we used health administrative data as a proxy to estimate incident AGWs and total health service utilisation (HSU) for AGWs for all Ontario residents 15 years and older with valid health cards between 1 April 2003 and 31 March 2007.

OUTCOME MEASURES

The outcome of interest was AGW healthcare utilisation identified using the International Classification of Diseases, 10th revision (ICD-10) diagnostic code for AGWs, as well as an algorithm for identifying AGW physician office visits in a database with a unique system of diagnostic and procedural codes. An AGW case was considered incident if preceded by 12 months without HSU for AGWs. Time trends by age group and sex were analysed.

RESULTS

Between fiscal years 2003 and 2006, we identified 123,247 health service visits for AGWs by 51,436 Ontario residents 15 years and older. Incident AGWs peaked in females and males in the 21-23 year age group, at 3.74 per 1000 and 2.81 per 1000, respectively. HSU for AGWs peaked in females and males within the 21-23 year age group, at 9.34 per 1000 and 7.22 per 1000, respectively.

CONCLUSIONS

To the best of our knowledge, this is the first population-based study of AGW incidence and HSU in Ontario. The sex and age distribution of individuals with incident and prevalent AGWs in Ontario was similar to that of other provinces before HPV vaccine programme implementation in Canada.

Increasing incidence of anogenital warts with an urban-rural divide among males in Manitoba, Canada, 1990-2011

Background

Anogenital warts (AGW) are caused by the most common sexually transmitted infection, human papillomavirus. The objective of this study was to examine AGW incidence from 1990 to 2011 by sex, age, income quintile, and residential area category (urban/rural). The study period included the initiation of school-based HPV vaccination for girls in the sixth grade, which began in 2008. The data presented in this paper may also be useful for establishing baseline rates of AGW incidence which may be used to evaluate the success of the school-based HPV immunization program.

Methods

Cases of anogenital warts were identified using Manitoba’s administrative databases of Physician Claims and Hospital Discharge Abstracts. Annual age-standardized incidence in Manitoba from 1990 to 2011 was calculated. Incident AGW rates were compared by sex, age group, residential area category (urban/rural), and household income quintile using logistic regression. Joinpoint regression analyses were used to evaluate the time trends of AGW.

Results

Prior to 2000, AGW incidence was higher among females than males. However, from 2000 to 2011 the incidence was higher among males and increased steadily over time. AGW incidence tended to peak in younger age groups among females compared to males. Females and males living in urban areas had nearly twice the odds of AGW occurrence compared to those in rural areas.

Conclusions

There is a need for education about AGW in male population. The upcoming initiation of HPV vaccination among boys may reduce the incidence and should be evaluated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2885-4) contains supplementary material, which is available to authorized users.