Opportunistic HPV vaccination at age 16-23 and cervical screening attendance in Sweden: a national register-based cohort study

Impact of HPV Vaccination on the Incidence of High-Grade Cervical Intraepithelial Neoplasia (CIN2+) in Women Aged 20-25 in the Northern Part of Norway: A 15-Year Study

BACKGROUND

Human papillomavirus (HPV), the most prevalent sexually transmitted infection globally, is a key risk factor for high-grade cervical lesions and cervical cancer. Since 2009, HPV vaccination has been part of the national immunization program for girls in 7th grade in Norway (women born 1997 and later). This study aimed to assess the impact of HPV vaccination on the incidence of high-grade cervical precursors (CIN2+) among women aged 20-25 in Troms and Finnmark over a 15-year period.

MATERIALS AND METHODS

In this time series study, we analyzed cervical screening data from 15,328 women aged 20-25 in Troms and Finnmark, collected between 2008 and 2022. Statistical methods, including linear and logistic regression, were employed to evaluate changes in cervical intraepithelial neoplasia grade 2 and worse (CIN2+) incidence and compare risks between vaccine-offered cohorts and pre-vaccine cohorts.

RESULTS

The incidence of CIN2+ initially increased from 31 cases per year in 2008 to 110 cases in 2018, then significantly decreased to 44 cases per year by 2022 (p < 0.01). Women in pre-vaccine cohorts had a substantially higher risk of CIN2+ (OR 9.02, 95% CI 5.9-13.8) and CIN3+ (OR 19.6, 95% CI 7.3-52.6). Notably, no vaccinated women with CIN2+ tested positive for HPV types 16 or 18. Furthermore, none of the 13 cervical cancer cases recorded during the study were from the vaccinated cohorts.

INTERPRETATION

The findings suggest a significant reduction in the incidence of high-grade cervical precursors following the introduction of the HPV vaccine in Norway's national immunization program, highlighting its effectiveness in cervical cancer prevention among young women in Northern Norway.

Social factors and age play a significant role in cervical cancer and advanced-stage disease among Danish women

BACKGROUND

For cervical cancer (CC), the implementation of preventive strategies has the potential to make cervical cancer occurrence and death largely avoidable. To better understand the factors possibly responsible for cervical cancer, we aimed to examine possible differences in age and social parameters as well as screening status between women with low- or high-stage cervical cancer and matched controls.

METHODS

Through the Danish Cancer Registry (DCR), women diagnosed with cervical cancer in Denmark between 1987 and 2016 were included. These were age- and residence-matched in a 1:5 ratio with controls from the general female population. The study population was sub grouped into a low-stage subpopulation with women with early-stage cervical cancer and matched controls and a high-stage subpopulation with women with late-stage cervical cancer and matched controls. Age and social parameters were compared within the subpopulations as well as between low- and high-stage cases. For part of the study population, screening attendance was examined to compare differences in adherence.

RESULTS

Overall, we found that the risk of cervical cancer is significantly increased in socially disadvantaged women and not least non-attenders in screening. Interestingly, the high-stage subpopulation was significantly older than the low-stage subpopulation (p < 0.001), and when examining the impact of age further, we found that for cervical cancer cases, the risk of having low-stage disease decreases significantly with increasing age, whereas the risk of having high-stage disease increases significantly with increasing age. In the screening cohort, significantly less cases than controls were attenders in screening with the most pronounced differences seen in the old subpopulation (women aged 50-64 years) and in the high-stage subpopulation (p-values all < 0.001). Interestingly, when examining the risk of CC for attenders and non-attenders, we demonstrated that many social parameters continue to influence the risk of cervical cancer, even in women attending screening.

CONCLUSIONS

Older women, socially disadvantaged women, and non-attenders in screening are particularly vulnerable in terms of developing cervical cancer, especially high-stage disease. Therefore, improvements in the participating rate in screening as well as a revision of the current screening guidelines are needed.

The Consensus Project: Participation in cervical cancer screening by the first cohorts of girls offered HPV vaccination at age 15-16 years in Italy

OBJECTIVE

To evaluate the association between human papillomavirus vaccination status and participation in cervical cancer screening (at age 25) by the first cohorts of girls who were offered vaccination at the age of 15 to 16 years in Italy.

METHODS

Women born in 1993, 1994 and 1995 were invited to participate in cervical cancer screening between 2018 and 2020. We report participation in screening by vaccination status in three large areas, Florence province, Piedmont region and Savona province, where the Consensus Project was carried out. The relative risk of participation among vaccinated (≥2 doses) and unvaccinated women was estimated. Odds ratios (OR) of participation by vaccination status were estimated by logistic regression, adjusted by birthplace and birth cohort.

RESULTS

Overall, 34,993 women were invited for screening: 13,006 (37.2%) participated and 10,062 of these agreed to participate in the Consensus intervention study. Among the invited women and screening participants, vaccinated women were 51.0% and 60.6%, respectively. Comparing vaccinated and unvaccinated women, the adjusted OR of screening participation was 1.80 (95% confidence interval (CI): 1.72-1.89), 2.17 (95% CI: 1.94-2.42), 1.59 (95% CI: 1.50-1.68) and 1.15 (95% CI: 0.86-1.54) for overall, Florence, Piedmont and Savona, respectively. About 33% of the invited women were unvaccinated and did not participate in screening: 25.8%, 59.5% and 64.2% of women born in Italy, in high migration pressure countries and in advanced development countries, respectively.

CONCLUSIONS

Screening participation was higher among vaccinated than unvaccinated women. Active policies are needed to reduce inequalities, targeting the unscreened and unvaccinated population, particularly non-native women, to accelerate cervical cancer elimination in Italy.

HPV Opportunistic Vaccination: A Literature Review and a Single-Center Experience in Northern Italy through the COVID-19 Pandemic

The World Health Organization (WHO) set the goal of 90% HPV vaccination coverage in the population to eliminate cervical cancer. Opportunistic vaccination is performed outside the free vaccination or catch-up programs. Both free and opportunistic HPV vaccination programs experienced slowdowns during the COVID-19 pandemic. In this retrospective study, we aimed to identify the benefits and the obstacles of opportunistic vaccination among male and female individuals who took advantage of the "on-demand" service offered by San Raffaele Hospital in Milan from April 2018 to May 2023. The impact that the COVID-19 pandemic had on vaccination adherence was also analyzed. Data on a total of 527 subjects were collected from an in-house database and through personal interviews. Women in the cohort of older patients (over 25) adhered to the vaccination schedule more than younger women. Opportunistic vaccination request is influenced by the need of a gynecologist, a general practitioner, or public health clinic availability. Women also showed good adherence to screening, demonstrating awareness of the importance of cervical cancer secondary prevention despite vaccination. Opportunistic vaccination offers the possibility of including individuals excluded from the free vaccination campaigns, often already affected by lesions caused by HPV, providing increased viral clearance and faster lesion regression. The main limit remains the economic burden.

"A lot can happen in five years": Women's attitudes to extending cervical screening intervals

OBJECTIVE

Evidence suggests that cervical screening intervals can be extended and lifetime cervical screening for human papillomavirus (HPV)-vaccinated women could be reduced. This study examines UK women's attitudes to extending screening intervals and assesses associations between knowledge, risk perception and HPV vaccination status, and acceptability of changes.

METHODS

Using a convenience sampling strategy, an anonymous mixed-methods online survey was used and data recorded from 647 women (mean age = 28.63, SD = 8.69).

RESULTS

Across the full sample, 46.1% of women indicated they would wait 5 years for their next cervical screening, while 60.2% of HPV-vaccinated women would be unwilling to have as few as three cervical screens in a lifetime. Multivariate analysis revealed those who are regular screened, those who intend to attend when invited, and those who perceive greater personal risk of cervical cancer are less likely to accept a 5-year screening interval. Qualitative findings relating to benefits of extending intervals included convenience of less tests, less physical discomfort, and psychological distress. Concerns identified included the likelihood of developing illness, increased psychological distress relating to what may be happening in the body, and worries about increased risk of cervical cancer.

CONCLUSION

Women need clear and specific information about HPV timelines, their relationship with cancer risk, and the rationale for extending screening intervals.

Cervical cancer screening guidelines and screening practices in 11 countries: A systematic literature review

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Screening guidelines and practices are heterogenous across 11 countries researched.

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Differences persist between screening guidelines and practices within countries.

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Only 6 of 11 countries here examined have national screening registries in place.

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Robust data infrastructure is essential to evaluate screening performance.

The World Health Organization (WHO) advocates population-based screening programs to reduce the global incidence of cervical cancer. However, screening guidelines and practice continually change to reflect scientific developments. Here we describe and compare cervical cancer screening guidelines and clinical practice in 11 countries across North America, Europe, and Asia-Pacific. We conducted a systematic literature review (SLR) complemented by a targeted literature review (TLR) to identify relevant peer-reviewed publications and policy documents, which include 120 publications, of which 86 were identified from the SLR and 34 from the TLR. Only six of 11 countries assessed have population-based screening programs in place. Considerable differences persist across countries’ screening guidelines, even among comparable systems. Moreover, methods of data collection are also heterogenous, and systematic data collection is often not established. As future changes in screening guidelines and clinical practice occur (e.g., when the first cohorts of women vaccinated against HPV reach screening age), systematic collection of screening data is essential to monitor and improve screening performance.

Association of human papillomavirus vaccination with cervical cancer screening: A systematic review and meta-analysis

INTRODUCTION

Prophylactic vaccination and routine screening are effective at preventing most cases of cervical cancer. Globally, cervical cancer is the fourth most frequently diagnosed cancer among women. The aim of this study was to investigate the association between human papillomavirus virus (HPV) vaccination (1, 2, or 3 doses) and cervical cancer screening.

METHODS

PubMed (MEDLINE), Scopus, Web of Science, and Cochrane Library electronic databases were systematically searched from July 1, 2006, up to September 30, 2021. We pooled estimates using random-effects models. Heterogeneity between studies was quantified using Cochran Q test and I2 statistics. In total, 12 studies involving 2.4 million individuals were included in the meta-analysis.

RESULTS

In the adjusted estimates, uptake of HPV vaccination was associated with increased cervical cancer screening (pooled relative risk [RR]: 1.35; 95% confidence interval [CI]: 1.21, 1.50; n = 12). Between-study heterogeneity was large (I2 = 99%). Compared to unvaccinated, those who received 3 doses of HPV vaccine had the highest uptake of cervical cancer screening (RR: 1.85; 95% CI: 1.58, 2.17), followed by those who received 2 doses (RR: 1.34; 95% CI: 1.21, 1.47). No statistically significant association with screening was found for those who received a single dose of the HPV vaccine.

CONCLUSION

In this meta-analysis, uptake of HPV vaccination was associated with higher cervical cancer screening. It is plausible that vaccinated individuals are more likely to engage in preventive health behaviors. Healthcare providers should remind patients to continue with routine screening for cervical cancer regardless of their HPV vaccine status since vaccination does not protect against all HPV types.

Young Danish HPV vaccinated women's knowledge, barriers and facilitators towards cervical cancer screening: A qualitative study

Cervical cancer occurs more often in under-screened women, and participation rates in cervical cancer screening among young women are worryingly low worldwide. In Denmark only about half the women in their twenties participate in cervical cancer screening. 64-80% of women between 20 and 29 have been HPV vaccinated with a vaccine protecting against 70% of all cervical cancers. Thus screening is still an important supplement to HPV vaccination for the next decades. The aim of this study was to investigate knowledge, facilitators and barriers towards cervical cancer screening among young HPV vaccinated women in Denmark. This qualitative study used an anthropological approach, and data was collected using semi structured focus group interviews as this is an effective method for promoting self-disclosure among participants. Eight focus groups were conducted with participation of 49 HPV vaccinated women aged 20-29 years. We identified five main themes providing an understanding of the women's barriers and facilitators towards cervical cancer screening: Lack of knowledge about HPV and cervical cancer, the screening invitation, the GP as gatekeeper, the gynaecological examination and perceived relevance of cervical cancer screening. Former vaccination did not impact the women's reflection about screening attendance. We argue that systematic information and the attitude and tone of the GP are the primary facilitators for filling the knowledge gap we found among young HPV vaccinated women. As an important gatekeeper, the GP can explain, motivate and remind young women about the importance of a regular Pap smear.

Sexual behavior, clinical outcomes and attendance of cervical cancer screening by HPV vaccinated and unvaccinated sexually active women

Concerns were raised about HPV vaccination possibly leading to riskier sexual behavior. We assessed sexual behaviors, risk of sexually transmitted infection, and attendance to cervical cancer screening by HPV vaccinated and unvaccinated young women. In this analysis, 1475 questionnaires completed by women aged 17-29 years were included. The majority of respondents (67.9%) were vaccinated against HPV. The proportion of those vaccinated decreased with age: from 93.2% in those aged 17-19 to 72.9% in those aged 20-22, and 21.8% in 23-29-year olds. A higher proportion of unvaccinated respondents had at least one sexual intercourse under the age of 15 when compared to those vaccinated (30% vs. 23%, p < .0001). The number of sexual partners during the last 12 months was similar between vaccinated and unvaccinated participants. Vaccinated participants reported more condom use (45% versus 38%; p = .0002), and less sexually transmitted infections (10% versus 28%; p < .0001), and less anogenital condylomas (2.2% vs. 11.6%; p < .0001). A screening test has been reported by 51% and 77% of vaccinated and unvaccinated participants, respectively (p < .0001). The association between vaccination status and cervical cancer screening disappeared when adjusting for participants' age. The study results consolidate the existing body of data regarding the absence of an impact of HPV vaccination on sexual behavior or use of contraceptives.

Sociodemographic Correlates of Human Papillomavirus Vaccine Uptake: Opportunistic and Catch-Up Vaccination in Norway

Simple Summary

HPV vaccination protects against virus that may cause cervical cancer. Opportunistic HPV vaccination (i.e., vaccination at a citizens’ own initiative and cost) has been available in Norway since the first HPV vaccine was licensed in 2006. A routine HPV vaccination program targeting 12-year-old girls was introduced in 2009. A delayed catch-up vaccination program was initiated in 2016, offering HPV vaccination free-of-charge to women born in 1991 and later who had not previously been vaccinated in the routine program. The aim of this study was to assess sociodemographic correlates of opportunistic and catch-up HPV vaccine uptake among women in Norway. We found inequalities in both self-paid opportunistic and free-of-charge catch-up HPV vaccine uptake among adolescents and adult women, with particularly low uptake among women with two immigrant parents and among women with a low household income.

Abstract

Achieving equity in human papillomavirus (HPV) vaccination has high priority. In this nationwide registry-based study, we aimed to investigate sociodemographic correlates of HPV vaccine uptake among women who were vaccinated opportunistically at their own initiative and cost during October 2006–June 2018, and among women who were vaccinated free-of-charge in a catch-up vaccination program during November 2016–June 2018. For 840,328 female residents born in Norway between 1975 and 1996, we retrieved HPV vaccination and sociodemographic data from national registries. We used separate models to analyze the sociodemographic correlates of the initiation and completion of HPV vaccination in opportunistic and catch-up vaccination settings. Overall initiation rate for opportunistic HPV vaccination was 2.2%. Uptake increased consistently with birth year, maternal education level, and household income. Having two immigrant parents or a mother working in a lower prestige occupation was strongly associated with low opportunistic vaccination uptake. Similar but weaker inequities were observed in catch-up HPV vaccination. Initiation rate during the first 20 months of the catch-up program was 46.2%. Completion rate was 72.1% and 73.0% for opportunistic or catch-up vaccination, respectively, with small inequities. In conclusion, HPV vaccine uptake was strongly associated with sociodemographic background both in opportunistic and catch-up vaccination settings, with particularly low uptake associated with having two immigrant parents and low household income.

A Retrospective Cohort Study of Young Women Spontaneously Choosing to Be Vaccinated against HPV: Outcomes from Their First Cervical Cancer Screening Test

Background: Efficacy for cervical cancer prevention of opportunistic HPV vaccination in post-pubertal girls is lower than in 11-year-olds. Methods: Women born between 1986 and 1992 vaccinated at 15–25 years of age (at least one dose of 4-valent HPV vaccine) and screened at 24–27 years of age were included. Frequency of opportunistic vaccination, overall and by birth cohort, was calculated; screening outcomes were compared between vaccinated and unvaccinated women. Results: Overall, 4718 (4.9%) HPV-vaccinated, and 91,512 unvaccinated, women were studied. The frequency of vaccination increased by birth cohort, ranging between 1.8% and 9.8%; age at vaccination decreased progressively by birth cohort (p < 0.0001). Participation in screening was 60.8% among vaccinated, and 56.6% among unvaccinated, women (p < 0.0001). Detection rates (DR) for high-grade lesions were lower in vaccinated women (2.11‰ vs. 3.85‰ in unvaccinated, for CIN3+, p = 0.24; 0.0‰ vs. 0.22‰ for cancer). The DR of CIN3+ increased with age at vaccination, scoring respectively 0.0‰, 0.83‰, and 4.68‰ for women vaccinated when they were 15–16, 17–20, and 21–25 years old (p = 0.17). Conclusions: In comparison to unvaccinated women, higher compliance with cervical cancer screening invitation and lower CIN3+ DR among vaccinated women was observed. Age at vaccination was inversely correlated to vaccination efficacy.

Catch-up HPV Vaccination and Subsequent Uptake of Papanicolaou Testing in A State-mandated Health System

The objective of this study was to evaluate the association between human papillomavirus (HPV) vaccination and uptake of initial Papanicolaou (Pap) testing in Israel among women not previously vaccinated through the national immunization program. In this retrospective cohort we used health provider records of vaccinations and cancer screening attendance among female members of a state-mandated health provider in Israel (Maccabi Healthcare Services, MHS). All eligible female members (N = 20,904) immunized with at least one dose of HPV vaccine from the date of its introduction in Israel (June 2007) until December 31, 2018 were individually matched with nonvaccinated MHS members on one to one ratio by year of birth, residential area socioeconomic level, and district of residence. Data on the uptake of Pap smears until December 2018 were extracted from MHS central datasets, and the number of Pap smears for each woman during the study period was counted. During the observed follow-up period (mean, 6.6 years; interquartile range, 3.9-8.7 year), the cumulative uptake rate of Pap testing in vaccinated women (26.8%) was significantly (P < 0.001) greater than among unvaccinated (22.4%) women. In a multivariable model, HPV vaccination was associated with an HR of 1.34 [95% confidence interval (CI), 1.29-1.41] to perform Pap testing. Our findings suggest that uptake of catch-up HPV vaccine was positively correlated to increased uptake of Pap testing. PREVENTION RELEVANCE: We found that catch-up HPV vaccination was associated with increased attention to long-term cervical screening attendance. Whereas, those who are not vaccinated and unprotected from HPV, are more likely to abstain from secondary prevention screening tests too and further increase their cervical cancer risk.

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

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

Declining rates of cervical intraepithelial neoplasia in British Columbia, Canada: An ecological analysis on the effects of the school-based human papillomavirus vaccination program

Since 2008, girls in British Columbia (BC), Canada, have been offered HPV vaccination through a school-based, publicly funded immunization program. The oldest birth cohort eligible for the vaccination program was born in 1994 and uptake is on average 63%. To evaluate the impact of the HPV vaccine in BC, ecological trends in cervical intraepithelial neoplasia (CIN) rates were assessed in young women before and after the implementation of the HPV vaccination program. Information on all Pap smears and histopathological abnormalities, in calendar years 2004-2017 in women 16-28 years of age in BC were obtained from the population-based BC Cancer Cervix Screening Program database. Rates of CIN 2 and 3 were calculated as the number of cases divided by the number of cytology specimens for that period. Rate ratios (RR) were calculated by negative binomial piecewise regression. Age-centered incidence rates of CIN 2 and 3 in BC declined significantly among women 16-23 years of age after HPV vaccine introduction compared to before vaccine introduction. The overall reduction postvaccination for CIN2 and 3 in women 16-23 years was respectively 62% (95% CI 54-68%) and 65% (95% CI 58-71%). Age-specific rates for CIN2 significantly declined for those 18-22 years of age and for those 19, 20 and 23 years of age for CIN3. Among women 24-28 years of age no decline in CIN2 and 3 rate over time was observed. The observed reduction in CIN 2 and 3 rates since the introduction of the school-based HPV vaccine program might illustrate the population impact of the BC provincial school-based HPV vaccination program.

HPV Vaccination and the Risk of Invasive Cervical Cancer

BACKGROUND

The efficacy and effectiveness of the quadrivalent human papillomavirus (HPV) vaccine in preventing high-grade cervical lesions have been shown. However, data to inform the relationship between quadrivalent HPV vaccination and the subsequent risk of invasive cervical cancer are lacking.

METHODS

We used nationwide Swedish demographic and health registers to follow an open population of 1,672,983 girls and women who were 10 to 30 years of age from 2006 through 2017. We assessed the association between HPV vaccination and the risk of invasive cervical cancer, controlling for age at follow-up, calendar year, county of residence, and parental characteristics, including education, household income, mother's country of birth, and maternal disease history.

RESULTS

During the study period, we evaluated girls and women for cervical cancer until their 31st birthday. Cervical cancer was diagnosed in 19 women who had received the quadrivalent HPV vaccine and in 538 women who had not received the vaccine. The cumulative incidence of cervical cancer was 47 cases per 100,000 persons among women who had been vaccinated and 94 cases per 100,000 persons among those who had not been vaccinated. After adjustment for age at follow-up, the incidence rate ratio for the comparison of the vaccinated population with the unvaccinated population was 0.51 (95% confidence interval [CI], 0.32 to 0.82). After additional adjustment for other covariates, the incidence rate ratio was 0.37 (95% CI, 0.21 to 0.57). After adjustment for all covariates, the incidence rate ratio was 0.12 (95% CI, 0.00 to 0.34) among women who had been vaccinated before the age of 17 years and 0.47 (95% CI, 0.27 to 0.75) among women who had been vaccinated at the age of 17 to 30 years.

CONCLUSIONS

Among Swedish girls and women 10 to 30 years old, quadrivalent HPV vaccination was associated with a substantially reduced risk of invasive cervical cancer at the population level. (Funded by the Swedish Foundation for Strategic Research and others.).

Low attendance by non-native women to human papillomavirus vaccination and cervical cancer screening - A Danish nationwide register-based cohort study

Background

Cervical cancer is preventable through human papillomavirus vaccination and cervical cancer screening. However, possibly due to systemic, individual (e.g. low socio-economic staus) and socio-cultural barriers, it is likely that non-natives, especially non-westerns, are more prone to attend neither vaccination nor screening (combined non-attendance). This is disturbing as the non-native population in Denmark is predicted to rise to 21% by 2060. We aimed to investigate differences in combined non-attendance by nativity and region of origin, and to analyse the association between country of origin and combined non-attendance adjusted for socio-economic status.

Setting

1.6.2007–31.12.2016 Denmark.

Methods

Logistic regression was performed to estimate crude and adjusted odds ratios with 95% confidence intervals for combined non-attendance.

Results

170,158 women were included. Overall combined non-attendance was 11.8% [11.7–12.0]; 10.0% [9.8–10.1] for native women and 27.1% [26.4–27.7] for non-native women, with highest degrees among Middle-Eastern and North-Africans (30.1% [29.2–30.9]). Even when adjusted for socio-economics, women from Middle-East and North-Africa had substantially higher odds of combined non-attendance than natives (adj. OR = 7.5 [6.3–8.9] for Somali women).

Conclusion

Denmark has a relatively low degree of combined non-attendance. However, cervical cancer preventive programmes seem to be better tailored to the needs of native women and do not appear to cater sufficiently to the needs of the fast-growing non-native populations, particularly not to the needs of Middle-Eastern and North African women. In order to secure more just cervical cancer prevention, future studies are recommended to develop tailored intervention sensitive to the need of non-native women.

Human papillomavirus types in cervical dysplasia among young HPV-vaccinated women: Population-based nested case-control study

Human papillomavirus (HPV) vaccines protect against infections with the most oncogenic HPV types, cervical intraepithelial neoplasia (CIN) and cervical cancer. We investigated whether development of cervical intraepithelial neoplasia (CIN) lesions in HPV-vaccinated women is associated with vaccine-targeted HPV types or not. Linkage of the Swedish vaccination and cervical screening registries identified all females born 1980-2000 who had been HPV vaccinated before December 31, 2014 (n = 305,320) and had attended cervical screening in 2006-2018 (n = 79,491). We further selected women HPV vaccinated below 17 years of age and screened in the capital region (n = 5,874). Among those, 125 developed CIN and had a cervical cryopreserved sample available (42.5% of all eligible CIN cases). After 1:2 matching to disease-free HPV vaccinated controls (n = 242), samples were analyzed for HPV DNA and associations between HPV type and CIN diagnosis were estimated with conditional logistic regression. Vaccine-targeted HPV types were rare among both CIN cases (2.4% HPV16, 0.8% HPV18) and their matched controls (0.4% HPV16 and 18). No woman had HPV6 or 11. The CIN lesions were associated with the nonvaccine HPV types 31, 33, 42, 45, 51, 52, 56, 59 and 66. CIN lesions among young HPV vaccinated women are mostly attributable to infection with nonvaccine HPV types. The phenomenon may be important for surveillance and design of cervical cancer control strategies.

Non-Adherence To Childhood HPV Vaccination Is Associated With Non-Participation In Cervical Cancer Screening - A Nationwide Danish Register-Based Cohort Study

Background

The combination of organized cervical cancer screening and childhood HPV vaccination programs has the potential to eliminate cervical cancer in the future. However, only women participating in both programs gain the full protection, and combined non-attenders remain at high risk of developing cervical cancer. Our aim was to analyze the association between non-adherence to HPV vaccination and non-participation in cervical cancer screening for the total population and stratified by native background and parental education.

Participants

Women born in 1993 eligible for both childhood HPV vaccination and first cervical cancer screening.

Analysis

Logistic regression models were used to estimate the odds ratio (OR) of non-participation in cervical cancer screening with 95% confidence intervals (CI). Stratified and adjusted logistic regression models were used along with the Wald test in order to test for interaction.

Results

24,828 women were included in the study. Among vaccinated women, 61.4% participated in cervical cancer screening; only 39.0% of unvaccinated women participated in cervical cancer screening. Unvaccinated and unscreened women were often non-native and had the lowest socio-economic status, whereas vaccinated and screened women were often native and had the highest socio-economic status. The adjusted OR for non-participation in cervical cancer screening was 2.07 [95% CI: 1.88–2.28] for unvaccinated compared to vaccinated women. After stratifying by country of origin, unvaccinated natives had the highest adjusted OR of not participating in cervical cancer screening compared to non-native women from both western and non-western countries (adjusted ORs of 2.2 [95% CI: 2.0–2.4], 1.3 [95% CI: 0.6–2.8], and 1.5 [95% CI: 1.1–2.0], respectively) (Wald test p=0.019).

Conclusion

Among natives, non-adherence to HPV vaccination and non-participation in screening seem to be signs of generally poor health-preventive behavior, whereas among non-natives from non-western countries, non-attendance in HPV vaccination and cervical cancer screening seem to be influenced by unrelated factors. Therefore, a differentiated and culturally sensitive approach is needed to enhance overall cervical cancer preventive behavior across different nativities.