Human Papillomavirus Prevalence Data Research Articles

Approximating missing epidemiological data for cervical cancer through Footprinting: A case study in India.

Local cervical cancer epidemiological data essential to project the context-specific impact of cervical cancer preventive measures are often missing. We developed a framework, hereafter named Footprinting, to approximate missing data on sexual behaviour, human papillomavirus (HPV) prevalence, or cervical cancer incidence, and applied it to an Indian case study. With our framework, we (1) identified clusters of Indian states with similar cervical cancer incidence patterns, (2) classified states without incidence data to the identified clusters based on similarity in sexual behaviour, (3) approximated missing cervical cancer incidence and HPV prevalence data based on available data within each cluster. Two main patterns of cervical cancer incidence, characterized by high and low incidence, were identified. Based on the patterns in the sexual behaviour data, all Indian states with missing data on cervical cancer incidence were classified to the low-incidence cluster. Finally, missing data on cervical cancer incidence and HPV prevalence were approximated based on the mean of the available data within each cluster. With the Footprinting framework, we approximated missing cervical cancer epidemiological data and made context-specific impact projections for cervical cancer preventive measures, to assist public health decisions on cervical cancer prevention in India and other countries.

Prevalence and genotype distribution of human papillomavirus infections in Beijing, China between 2016 and 2020

BackgroundCertain types of human papillomavirus (HPV) induce long-lasting infections that cause cervical cancer. This study evaluated the prevalence of HPV infections and the distribution of their genotypes among clinic patients and healthy women in Beijing, China.MethodsCervical specimens were collected from 12,100 patients and 1176 subjects who underwent physical examinations at Dongzhimen Hospital, Beijing University of Chinese Medicine, between March 2016 and September 2020. HPV genotyping was performed using commercial kits designed to detect 15 high-risk and 2 low-risk HPV genotypes.ResultsThere was a higher overall prevalence of HPV among the clinic patients (21.0%) than among the healthy women (11.9%). The most common HPV genotypes among the patients were: HPV-52 (5.4%), HPV-16 (3.4%), HPV-58 (3.2%), HPV-51 (2.6%), HPV-39 (2.0%), HPV-56 (2.0%), and HPV-66 (2.0%). Among the healthy women: HPV-52 (3.0%), HPV-51 (1.8%), HPV-58 (1.6%), HPV-66 (1.5%), HPV-16 (1.2%), HPV-56 (1.2%), and HPV-18 (1.1%). Multiple HPVs were detected in 29.1% of the gynecological outpatients and in 23.6% of the women receiving physical examinations. The most common pairs of HPV types detected were HPV-52 and HPV-16 in the clinic patients, and HPV-52 and HPV-56 in the healthy women. Age-specific HPV positivity and peak prevalence were observed among the individuals in both groups for women aged less than 25 years and those between 61 and 65 years of age.ConclusionsOur results provide current estimates of HPV prevalence and genotypes in the Beijing region. The epidemiological characteristics observed also provide a reference for the development of cervical cancer screening strategies and selection of HPV vaccine antigen targets for this region. A comparison of these HPV prevalence data with those from other regions suggests that regional vaccines may be an important direction for future research.

Evidence-based impact projections of single-dose human papillomavirus vaccination in India: a modelling study.

Despite the high burden of cervical cancer, access to preventive measures remains low in India. A single-dose immunisation schedule could facilitate the scale-up of human papillomavirus (HPV) vaccination, contributing to global elimination of cervical cancer. We projected the effect of single-dose quadrivalent HPV vaccination in India in comparison with no vaccination or to a two-dose schedule. In this modelling study, we adapted an HPV transmission model (EpiMetHeos) to Indian data on sexual behaviour (from the Demographic and Health Survey and the Indian National AIDS Control Organisation), HPV prevalence data (from two local surveys, from the states of Tamil Nadu and West Bengal), and cervical cancer incidence data (from Cancer Incidence in Five Continents for the period 2008-12 [volume XI], and the Indian National Centre for Disease Informatics and Research for the period 2012-16). Using the model, we projected the nationwide and state-specific effect of HPV vaccination on HPV prevalence and cervical cancer incidence, and lifetime risk of cervical cancer, for 100 years after the introduction of vaccination or in the first 50 vaccinated birth cohorts. Projections were derived under a two-dose vaccination scenario assuming life-long protection and under a single-dose vaccination scenario with protection duration assumptions derived from International Agency for Research on Cancer (IARC) India vaccine trial data, in combination with different vaccination coverages and catch-up vaccination age ranges. We used two thresholds to define cervical cancer elimination: an age-standardised incidence rate of less than 4 cases per 100 000 woman-years, and standardised lifetime risk of less than 250 cases per 100 000 women born. Assuming vaccination in girls aged 10 years, with 90% coverage, and life-long protection by two-dose or single-dose schedule, HPV vaccination could reduce the prevalence of HPV16 and HPV18 infection by 97% (80% UI 96-99) in 50 years, and the lifetime risk of cervical cancer by 71-78% from 1067 cases per 100 000 women born under a no vaccination scenario to 311 (80% UI 284-339) cases per 100 000 women born in the short term and 233 (219-252) cases per 100 000 women born in the long term in vaccinated cohorts. Under this scenario, we projected that the age-standardised incidence rate threshold for elimination could be met across India (range across Indian states: 1·6 cases [80% UI 1·5-1·7] to 4·0 cases [3·8-4·4] per 100 000 woman-years), while the complementary threshold based on standardised lifetime risk was attainable in 17 (68%) of 25 states, but not nationwide (range across Indian states: 207 cases [80% UI 194-223] to 477 cases [447-514] per 100 000 women born). Under the considered assumptions of waning vaccine protection, single-dose vaccination was projected to have a 21-100% higher per-dose efficiency than two-dose vaccination. Single-dose vaccination with catch-up for girls and women aged 11-20 years was more impactful than two-dose vaccination without catch-up, with reduction of 39-65% versus 38% in lifetime risk of cervical cancer across the ten catch-up birth cohorts and the first ten routine vaccination birth cohorts. Our evidence-based projections suggest that scaling up cervical cancer prevention through single-dose HPV vaccination could substantially reduce cervical cancer burden in India. The Bill & Melinda Gates Foundation.

Human papillomavirus seroprevalence in young Thai men

ABSTRACT Human papillomavirus (HPV) is one of the most common sexually transmitted infections in men and women. Most HPV studies have focused on vaccination toward women to prevent consequences of developing cervical cancer. However, persistent infections can cause penile, anal, and oropharyngeal cancers in men. Therefore, recent public health recommendations toward vaccination in men have been raised. There is limited HPV prevalence data among men in many countries, including Thailand. We conducted HPV sera IgG ELISA testing on a repository sera of Thai men (average age 21 years old) entering the Royal Thai Army as recruits in 2013 (n = 1000). HPV IgG antibodies against virus-like particles of HPV- type 6, 11, 16e, and 18 were evaluated using a commercial ELISA kit. Overall, the anti-HPV IgG was 47% (95% CI: 44%-50%). HPV seroprevalence was significantly associated with residence regions with the highest prevalence in South (64%), but not associated with educational level, marital status, or type of residence. This data suggested that almost half of the Thai men in this cohort were exposed to HPV by the age of 21. Thus, HPV vaccination provided to male adolescents should be considered for disease prevention and minimizing transmission to sexual partners.

Predicting Cohort-Specific Cervical Cancer Incidence From Population-Based Surveys of Human Papilloma Virus Prevalence: A Worldwide Study.

Predictions of cervical cancer burden and the impact of measures taken to control this cancer are usually data-demanding and based on complex assumptions. We propose a predictive method (called PANDORA) based on human papillomavirus (HPV) prevalence, measured 1993–2008, and cervical cancer incidence (CCI), measured 1993–2012, in the same birth cohorts from different worldwide locations, informed by data on age at detection of high-risk HPV and sexual debut. The model can predict CCI among high-risk HPV–positive women and predict CCI up to 14 years following high-risk HPV detection. We found CCI to increase during the 14 years following high-risk HPV detection in unscreened women aged <35 years but to remain mainly constant among women ≥35 years. Age at sexual debut was a significant modifier of CCI. Using our model, we accurately reproduced CCI among high-risk HPV–positive women as observed in cohort studies and in the general population of multiple countries. We also predicted the annual number of cervical cancer cases and CCI in locations with HPV prevalence data but no cancer registry. These findings could inform cervical cancer control programs in settings without cancer registries, as they can be used to predict future cervical cancer burden from population-based surveys of HPV prevalence.

Are associations between HIV and human papillomavirus transmission due to behavioural confounding or biological effects?

ObjectivesCohort studies have shown significant increased risk of HIV acquisition following human papillomavirus (HPV) detection and increased risk of new HPV detection in individuals with HIV infection, after adjusting for...

Evaluation of the performance of Human Papillomavirus testing in paired urine and clinician-collected cervical samples among women aged over 30\xa0years in Bhutan

BackgroundUrine sampling may offer a less invasive solution than cervical sampling to test for human papillomavirus (HPV) for HPV vaccine impact monitoring.MethodsPaired samples of urine and exfoliated cervical cells were obtained for 89 women with history of high-risk (HR) HPV-positive normal cytology in Bhutan. Urine sampling protocol included self-collection of first-void urine immediately into a conservation medium and procedures to optimize DNA yield. Colposcopical abnormalities were biopsied. Two HPV assays were used: a multiplex type-specific PCR (E7-MPG) and a less analytically sensitive GP5+/6+ PCR followed by reverse line blot.ResultsHPV positivity for 21 types common to both assays was similar in urine and cells by E7-MPG (62.9% and 57.3%, respectively, p = 0.32) but lower in urine by GP5+/6+ (30.3% and 40.4%, p = 0.05). HPV6/11/16/18 positivity did not significantly differ between urine and cells by either assay. Sensitivity of urine (using cells as gold standard) to detect 21 HPV types was 80% and 58% for E7-MPG and GP5+/6+, respectively, with specificity 61% and 89%. HPV type distribution in urine and cells was similar, regardless of assay. The 5 detected CIN3+ were HR-HPV positive in cells by both assays, compared to 4 and 3 by E7-MPG and GP5+/6+, respectively, in urine samples.ConclusionFor the monitoring of vaccine impact, we demonstrate validity of a urine sampling protocol to obtain HPV prevalence data that are broadly comparable to that from cervical cells. However, detection of HPV in urine varies according to assay sensitivity, presumably because low level infections are frequent.

HPV Vaccination Does Not Provide Herd Immunity for Unvaccinated Women or Cross-Protection for Nonvaccine HPV Types [12

INTRODUCTION: To determine if the human papillomavirus (HPV) vaccination offers cross-protection against nonvaccine HPV types and whether introduction of the vaccination has offered herd immunity to unvaccinated women. METHODS: We collected and analyzed HPV prevalence data for females aged 18–29 from the prevaccine era (2007–2008) and postvaccine era (2009–2012) using the National Health and Nutrition Examination Surveys (NHANES); 1628 female respondents aged 18–29, representing 21,135,134 females in the United States non-institutionalized civilian population, provided vaginal swabs across three consecutive NHANES survey cycles. RESULTS: Among females aged 18–29, the prevalence of high risk HPV among women who received at least one dose of the HPV vaccine decreased from 67% (95% confidence interval [CI] 50.7–81.4) in 2007–2008 to 41.5% (95% CI, 30.5–53.1) in 2011–2012; among the women vaccinated for HPV in the postvaccine era, the prevalence of HPV-16 and -18 was 6.4% versus 93.6% for all other high risk HPV types. There was no difference in prevalence in high risk HPV for women who did not receive the vaccine; 49.5% (95% CI, 42.5–56.6) in 2007–2008 versus 50.8% (95% CI, 43.0–58.7) in 2011–2012. CONCLUSION/IMPLICATIONS: The prevalence of high risk HPV significantly decreased among females aged 18–29 years who received the HPV vaccine, but there appeared to be no cross-protection against nonvaccine HPV types. These findings may offer support for usage of the investigational 9-valent HPV vaccine. There also was no evidence to suggest protection against HPV infection for unvaccinated women.

Prevalence of human papillomavirus in cancer of the oropharynx by gender.

Oropharyngeal cancer (OPC) is more frequent in men than women mainly due to the heavier and longer duration of smoking in men. Human papillomavirus (HPV) has a role in the rising incidence of OPC in the United States and other high-income countries. To determine whether there is a difference in the proportion of HPV-attributable OPC between men and women, we systematically retrieved HPV prevalence data from 63 studies reporting separately on OPC by gender. The male/female (M/F) ratios of HPV prevalence in OPC across different countries and the corresponding M/F ratios of cumulative lung cancer risk (a proxy for smoking) were compared. The United States had the highest M/F ratios of HPV prevalence in OPC (1.5). The lowest M/F ratios (≤0.7) were found in Asia and some European countries (e.g., France). The countries in which the M/F ratio of HPV prevalence in OPC was ≥1.0 had the most similar lung cancer risks for men and women. When HPV prevalence data were applied to age-standardized OPC incidence rates in the United States, Australia, the United Kingdom, and France, the M/F ratio for the HPV-positive OPC incidence rates was rather stable (around 4) in all countries. In contrast, the M/F ratio for the HPV-negative OPC incidence rates reached 10.2 in France versus <3 elsewhere. We showed that HPV prevalence in OPC differs by gender and country mainly as a consequence of the vast international variation in male smoking habits. Nevertheless, HPV-positive OPC may affect men more heavily than women in different populations for reasons that are unclear.

Highlights of This Issue

Oropharyngeal cancer (OPC) is more frequent in men than women due to heavier and longer smoking rates in men. To determine if there is a difference in the proportion of human papillomavirus (HPV)–attributable OPC between men and women, Combes and colleagues retrieved HPV prevalence data from 63 OPC studies with gender data. The authors report that the U.S. had the highest M/F ratios of HPV prevalence in OPC, and the lowest M/F ratios were found in Asia. This work confirmed that HPV prevalence in OPC differs by gender and country, most likely as a consequence of male smoking habits.Although physical activity (PA) is modifiable and linked to decreased breast cancer risk, its impact has not been investigated among indigenous African populations. Hou and colleagues recruited 558 breast cancer patients to complete a PA questionnaire. PA was significantly associated with reduced breast cancer risk in both pre- and postmenopausal women, with a dose–responsive relationship. The inverse association was present among lean women and overweight women, but not among obese women. PA of African women mainly consists of housework and work-related activities but this preliminary study suggests that modest PA may be significantly associated with reduced breast cancer risk.Organized human papillomavirus (HPV) vaccination was introduced in Sweden in 2012 and on-demand vaccination has been in effect from 2006–2011. Söderlund-Strand and colleagues followed HPV prevalences in Sweden from 2008 to 2013. The authors report that among 13- to 22-year-old women, HPV6, 16, and 18 decreased from 2008 to 2013. HPV vaccination rates among 23- to 40-year-old women were lower compared to the younger population and HPV18 decreased only marginally. Major reductions of HPV6, 16, and 18 were found in age groups with concomitant increases in HPV vaccination coverage.Lesser degrees of terminal duct lobular unit (TDLU) involution have been associated with increased breast cancer risk, but factors that influence involution are largely unknown. Khodr and colleagues assessed whether circulating hormones are associated with levels of TDLU involution. Among premenopausal women, higher prolactin levels were associated with higher TDLU counts but higher progesterone was associated with lower TDLU counts. Among postmenopausal women, higher levels of estradiol and testosterone were associated with higher TDLU counts. These data suggest that select hormones may influence breast cancer risk, potentially through delaying TDLU involution.

Human Papillomavirus (HPV) Prevalence and Types among Women Attending Regular Gynecological Visit in Tehran, Iran

Persistent infection by HPV is now recognized as the main cause of cervical cancer. HPV prevalence data is not yet available in Iran. This study is organized to evaluate type-specific HPV prevalence and to compare it with Pap smear results among Iranian women attending regular gynecological visits. A total of 851 women aged 18 - 65 years, attending regular gynecological visits, were retrospectively evaluated. HPV detection and genotyping was performed by use of Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP). Cytological evaluation was done by Papanicolaou method and the association between cytological results and HPV status was analyzed. 19 different HPV types were detected in 265 of the 851 specimens (31.1%). Overall HPV infection as well as infection with High Risk (HR) HPV types was highest in women aged 18 - 25 years and decreased with age. Type-specific prevalence of HPV-16 and 18 was 7.3% and 2.8%, respectively, and a large number of women (20.2%) were infected by HR HPV types other than HPV-16 and/or HPV-18. There was also an upward trend in the prevalence of HR HPV infections as the abnormality in cytology increased. The prevalence of HPV co-infection was 29.1% of HPV positive patients and declined from LSIL (18.2%) to HSIL (3.9%). Our study indicated that the burden of HPV infection among Iranian females was higher in comparison with previous estimates reported from Iran. Furthermore, higher prevalence of premalignant changes in Iranian women infected with HR HPV types, other than vaccine types, should be considered in immunization programs and development of population-specific HPV vaccines. This remarkable difference in prevalence of HPV types among previous studies, confirms our need to further investigations on epidemiology of HPV infection in Iran.

Young Gay Men and the Quadrivalent Human Papillomavirus Vaccine--Much to Gain (and Lose)

Human papillomavirus (HPV) is the world’s most common viral sexually transmitted infection [1, 2]. Approximately 40 HPV types infect anogenital squamous epithelium and can be broadly divided into low-risk (eg, HPV 6, 11) and high-risk (eg, HPV 16, 18) phenotypes based on their historical association with cervical cancer. This relationship also holds true for other anogenital (anal, vulvar, vaginal) and oropharyngeal malignancies. Although most HPV infections are asymptomatic, when symptoms do occur, they often reflect the presence of warts, dysplasia, or frank malignancy. Anogenital HPV infection is mostly transient in both sexes, with persistent high-risk HPV infection associated with the development of squamous-cell cancers [3, 4]. HPV prevalence data vary by gender, with men being more likely to have higher-level detection over a wider age range than women, whose prevalence decreases from a peak in their early 20s [3, 5] However, it is men who have sex with men (MSM) who have the highest rates of anogenital HPV infection and also HPV-associated malignancy, particularly HPV 16–associated anal cancer [6, 7]. HPV vaccination has been shown to be safe and effective in preventing the acquisition of anogenital HPV infection and the development of dysplasia [8–10]. The challenge ahead is to ensure that vaccinations are available to those at risk in a manner that optimizes their efficacy. There are 2 licensed HPV vaccines: a bivalent vaccine directed against HPV 16 and 18 (Cervarix, GlaxoSmithKline, London, UK) licensed for females aged 9–25 years, and a quadrivalent HPV vaccine (qHPV) directed against HPV 6, 11, 16, and 18 (Gardasil, Merck, Whitehouse Station, NJ) licensed for females and males ages 9–26 years. Both vaccines’ indications include prevention of warts and female genital dysplasia/cancer, with qHPV also indicated for anal dysplasia/ cancer. These prophylactic vaccines induce high-titer HPV antibody levels with good efficacy and an excellent safety profile [11, 12]. In this issue of The Journal of Infectious Diseases, Zou and colleagues examined acquisition of anogenital HPV in a population of MSM. They enrolled men between the ages of 16 and 20 years who self-identified as same-sex attracted. Thus, they were able to assess incident HPV infection in MSM with limited sexual experience who might benefit from HPV vaccination if they had the same access to HPV vaccines as adolescent girls. Following recruitment from a variety of venues, participants were seen for assessments at baseline and then at 3, 6, and 12 months. At each visit, participants had a clinical exam, completed a sexual experience questionnaire, had a blood sample drawn for HPV serology, and swabs taken from penile, perianal, and intra-anal sites. An oral saline gargle was also collected. All these samples were tested for HPV DNA by polymerase chain reaction. Additionally, participants were tested for gonorrhea, chlamydia, syphilis, and HIV at each visit. At the 12-month visit, participants were offered the qHPV. The median age of study participants was 19 years and the majority had engaged in both receptive and insertive anal intercourse. Thirty-nine percent of participants had at least 1 of 37 HPV types tested for at the anatomical sites sampled, and 23% had at least 1 qHPV type. Overall, at least 1 high-risk HPV was detected in 31% of participants. In participants with 0 to ≥4 receptive and insertive anal-sex partners, the respective proportion of anal (P < .001) and penile (P < .014) HPV increased significantly. This trend also reached significance for detection of anal HPV 16. In another study conducted in a slightly older age group of 94 MSM with a mean age of 21 years, 70% had any of the 37 HPV types tested for, and 37% had HPV 16 or 18. The incidence of anal HPV infection in this group was 38.5 and 15.3 per 1000 Received and accepted 4 November 2013. Correspondence: Ross D. Cranston, MB ChB, MD, FRCP, University of Pittsburgh, 3520 Fifth Ave, Keystone Bldg, Ste 510, Pittsburgh, PA 15213 (rdc27@pitt.edu). The Journal of Infectious Diseases © The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals. permissions@oup.com. DOI: 10.1093/infdis/jit627

Reduction in Human Papillomavirus (HPV) Prevalence Among Young Women Following HPV Vaccine Introduction in the United States, National Health and Nutrition Examination Surveys, 2003–2010

Human papillomavirus (HPV) vaccination was introduced into the routine immunization schedule in the United States in late 2006 for females aged 11 or 12 years, with catch-up vaccination recommended for those aged 13-26 years. In 2010, 3-dose vaccine coverage was only 32% among 13-17 year-olds. Reduction in the prevalence of HPV types targeted by the quadrivalent vaccine (HPV-6, -11, -16, and -18) will be one of the first measures of vaccine impact. We analyzed HPV prevalence data from the vaccine era (2007-2010) and the prevaccine era (2003-2006) that were collected during National Health and Nutrition Examination Surveys. HPV prevalence was determined by the Linear Array HPV Assay in cervicovaginal swab samples from females aged 14-59 years; 4150 provided samples in 2003-2006, and 4253 provided samples in 2007-2010. Among females aged 14-19 years, the vaccine-type HPV prevalence (HPV-6, -11, -16, or -18) decreased from 11.5% (95% confidence interval [CI], 9.2-14.4) in 2003-2006 to 5.1% (95% CI, 3.8-6.6) in 2007-2010, a decline of 56% (95% CI, 38-69). Among other age groups, the prevalence did not differ significantly between the 2 time periods (P > .05). The vaccine effectiveness of at least 1 dose was 82% (95% CI, 53-93). Within 4 years of vaccine introduction, the vaccine-type HPV prevalence decreased among females aged 14-19 years despite low vaccine uptake. The estimated vaccine effectiveness was high.

Epidemiological Features of Human Papillomavirus (HPV) Infection among Women Living in Mainland China

Cancer of the cervix is the third most common cancer in women worldwide, more than 85% of the cases occurring in developing countries such as China. In China, since a national cancer registry is already set up but with geographically limited data generated, the burden of cervical cancer is believed to be underestimated. High- risk human papillomavirus (HR-HPV) prevalence among women attending routine cervical cancer screening programs has been shown to correlate well with cervical cancer incidence rates based on independently obtained HPV prevalence data as well as findings for the worldwide cervical cancer burden. Therefore, reviewing data on HR-HPV prevalence in population-based screening studies and hospital-based case studies will be important in the context of better understanding the cervical cancer burden and for the evaluation of the potential impact of HPV vaccination in the country. With the advent of prophylactic vaccines, significant progress is likely to be made in cervical cancer prevention. This article reviews available data on the HPV epidemiology over a 12-year time period (2001-2012) in mainland China under different epidemiological aspects: by age group of study population, by ethnicity, by geographic area, as well as time period. The authors also review the potential acceptability of HPV vaccination among Chinese women.

Estimating the Effectiveness of HPV Vaccination in the Open Population: A Bayesian Approach

ObjectivesEstimation of the effectiveness of human papillomavirus (HPV) vaccination in the open population on the basis of published data from various sources. MethodsA Bayesian approach was used to reanalyze the data underlying a guidance by the Dutch National Health Insurance Board about the quadrivalent HPV vaccine Gardasil. Several studies document the vaccine’s effectiveness in preventing cases in different subpopulations. None of these (sub)populations, however, is representative of the actual target population that the vaccination program will be applied to. We used a Bayesian approach for restructuring the data by means of reweighting the subpopulations by using HPV prevalence data, to estimate the effectiveness that can be expected in the actual target population. ResultsThe original data show an effectiveness of 44% in the entire population and an effectiveness of 98% for women who were compliant and were HPV-free at the start of the study. In the study population, the HPV prevalence was below 4%. In the relevant target population, however, the actual prevalence could be very different. In fact, some publications find an HPV prevalence of around 10%. We used Bayesian techniques to estimate the effectiveness in the actual target population. We found a mean effectiveness of 25%, and the probability that the effectiveness in the target population exceeds 50% is virtually zero. The results are very sensitive to the HPV prevalence that is used. ConclusionsA supplementary analysis can put together the bits and pieces of information to arrive at more relevant answers. A Bayesian approach allows for integrating all the evidence into one model in a straightforward way and results in very intuitive probability statements.

Inference of Type-Specific HPV Transmissibility, Progression and Clearance Rates: A Mathematical Modelling Approach

Quantifying rates governing the clearance of Human Papillomavirus (HPV) and its progression to clinical disease, together with viral transmissibility and the duration of naturally-acquired immunity, is essential in estimating the impact of vaccination programmes and screening or testing regimes. However, the complex natural history of HPV makes this difficult. We infer the viral transmissibility, rate of waning natural immunity and rates of progression and clearance of infection of 13 high-risk and 2 non-oncogenic HPV types, making use of a number of rich datasets from Sweden. Estimates of viral transmissibility, clearance of initial infection and waning immunity were derived in a Bayesian framework by fitting a susceptible-infectious-recovered-susceptible (SIRS) transmission model to age- and type-specific HPV prevalence data from both a cross-sectional study and a randomised controlled trial (RCT) of primary HPV screening. The models fitted well, but over-estimated the prevalence of four high-risk types with respect to the data. Three of these types (HPV-33, -35 and -58) are among the most closely related phylogenetically to the most prevalent HPV-16. The fourth (HPV-45) is the most closely related to HPV-18; the second most prevalent type. We suggest that this may be an indicator of cross-immunity. Rates of progression and clearance of clinical lesions were additionally estimated from longitudinal data gathered as part of the same RCT. Our estimates of progression and clearance rates are consistent with the findings of survival analysis studies and we extend the literature by estimating progression and clearance rates for non-16 and non-18 high-risk types. We anticipate that such type-specific estimates will be useful in the parameterisation of further models and in developing our understanding of HPV natural history.

Prevalence of type-specific HPV infection by age and grade of cervical cytology: data from the ARTISTIC trial

Human papillomavirus (HPV) infection causes cervical cancer and premalignant dysplasia. Type-specific HPV prevalence data provide a basis for assessing the impact of HPV vaccination programmes on cervical cytology. We report high-risk HPV (HR-HPV) type-specific prevalence data in relation to cervical cytology for 24 510 women (age range: 20–64; mean age 40.2 years) recruited into the ARTISTIC trial, which is being conducted within the routine NHS Cervical Screening Programme in Greater Manchester. The most common HR-HPV types were HPV16, 18, 31, 51 and 52, which accounted for 60% of all HR-HPV types detected. There was a marked decline in the prevalence of HR-HPV infection with age, but the proportion due to each HPV type did not vary greatly with age. Multiple infections were common below the age of 30 years but less so between age 30 and 64 years. Catch-up vaccination of this sexually active cohort would be expected to reduce the number of women with moderate or worse cytology by 45%, but the number with borderline or mild cytology would fall by only 7%, giving an overall reduction of 12% in the number of women with abnormal cytology and 27% in the number with any HR-HPV infection. In the absence of broader cross-protection, the large majority of low-grade and many high-grade abnormalities may still occur in sexually active vaccinated women.

Prospective follow-up of Japanese women with cervical intraepithelial neoplasia and various human papillomavirus types

Objective: To evaluate the prevalence of genital human papillomavirus (HPV) types in cervical neoplasias and to evaluate the biological activity of individual HPV types in cervical carcinogenesis. Method: Cellular samples from 318 patients with cervical intraepithelial neoplasia (CIN) or invasive cervical carcinoma were examined for HPV DNA, using a polymerase chain reaction. Of these, 145 women with CIN grade I or II were prospectively followed to better understand the natural history of these precancerous lesions. Result: HPV DNA was detected in 88, 80 and 89%, of CIN grade I, II and III, respectively, and in 92% in invasive carcinomas. The CIN follow-up data showed a significantly higher progression rate in patients with CIN II than in cases of CIN I, and our classification of HPV types based on HPV prevalence data correlates well with the prospective follow-up data. A significantly higher progression rate was observed in HPV-negative CINs. Conclusion: Classification of HPV types according to risk to a malignant state seems to be possible. It seems that HPV negative lesions are likely to progress to a malignant state.