Teresa Cummings

Population-level impact and herd effects following human papillomavirus vaccination programmes: a systematic review and meta-analysis.

BACKGROUND Human papillomavirus (HPV) vaccination programmes were first implemented in several countries worldwide in 2007. We did a systematic review and meta-analysis to assess the population-level consequences and herd effects after female HPV vaccination programmes, to verify whether or not the high efficacy reported in randomised controlled clinical trials are materialising in real-world situations. METHODS We searched the Medline and Embase databases (between Jan 1, 2007 and Feb 28, 2014) and conference abstracts for time-trend studies that analysed changes, between the pre-vaccination and post-vaccination periods, in the incidence or prevalence of at least one HPV-related endpoint: HPV infection, anogenital warts, and high-grade cervical lesions. We used random-effects models to derive pooled relative risk (RR) estimates. We stratified all analyses by age and sex. We did subgroup analyses by comparing studies according to vaccine type, vaccination coverage, and years since implementation of the vaccination programme. We assessed heterogeneity across studies using I(2) and χ(2) statistics and we did trends analysis to examine the dose-response association between HPV vaccination coverage and each study effect measure. FINDINGS We identified 20 eligible studies, which were all undertaken in nine high-income countries and represent more than 140 million person-years of follow-up. In countries with female vaccination coverage of at least 50%, HPV type 16 and 18 infections decreased significantly between the pre-vaccination and post-vaccination periods by 68% (RR 0·32, 95% CI 0·19-0·52) and anogenital warts decreased significantly by 61% (0·39, 0·22-0·71) in girls 13-19 years of age. Significant reductions were also recorded in HPV types 31, 33, and 45 in this age group of girls (RR 0·72, 95% CI 0·54-0·96), which suggests cross-protection. Additionally, significant reductions in anogenital warts were also reported in boys younger than 20 years of age (0·66 [95% CI 0·47-0·91]) and in women 20-39 years of age (0·68 [95% CI 0·51-0·89]), which suggests herd effects. In countries with female vaccination coverage lower than 50%, significant reductions in HPV types 16 and 18 infection (RR 0·50, 95% CI 0·34-0·74]) and in anogenital warts (0·86 [95% CI 0·79-0·94]) occurred in girls younger than 20 years of age, with no indication of cross-protection or herd effects. INTERPRETATION Our results are promising for the long-term population-level effects of HPV vaccination programmes. However, continued monitoring is essential to identify any signals of potential waning efficacy or type-replacement. FUNDING The Canadian Institutes of Health Research.

REDUCTION OF HPV INFECTIONS THROUGH VACCINATION AMONG AT-RISK URBAN ADOLESCENTS

INTRODUCTION Human papillomavirus (HPV) vaccine trials have demonstrated high efficacy in preventing HPV infections and HPV related disease in females ages 16-26. However, there is no source data to demonstrate the impact of the vaccine in other populations who may be at higher risk for HPV related disease. This study examines the impact of HPV vaccination on subsequent HPV detection and sexual behaviors among urban adolescents in a clinical setting. METHODS A cohort of adolescent women, ages 14-17, were recruited prospectively and matched to historical controls to assess the impact of HPV vaccination. All women completed the same questionnaire and face-to-face interview that assessed sexual behaviors; all provided a clinician or self-collected vaginal swab that was used to test for sexually transmitted infections, including HPV. Logistic regression models, incorporating random pair effects, were used to assess the impact of the HPV vaccine on HPV detection and sexual behaviors between the two groups. RESULTS Each woman recruited (N=75) was matched to 2 historical controls (HC); most of the recruited women (89.3%) had received one or more doses of the HPV vaccine. At enrollment, detection of quadrivalent vaccine types (HPV 6, 11, 16 and 18) was significantly less in the recruited group (5.3%) as compared to the HC (24%): OR=5.6 (CI=1.9, 16.5), p=0.002. Adolescent women in the HC had a 9.5 times greater odds of HPV infection when the analysis was adjusted to compare those who had 2 or more vaccine doses to their matched controls. The only behavioral difference found was that the recruited women used condoms more frequently. CONCLUSION This study demonstrates that HPV vaccination was associated with fewer vaccine-type HPV infections despite incomplete vaccination and high risk sexual behaviors. These data also suggest that sexual behaviors were not altered because of the vaccine.

Accuracy of Self-Reported Human Papillomavirus Vaccine Receipt Among Adolescent Girls and Their Mothers

PURPOSE The use of self-report of human papillomavirus (HPV) vaccination status has several implications for clinical care and research. Reports of HPV vaccination history of adolescent girls (ages: 14-17 years) and their mothers were compared with medical chart data to assess the accuracy of HPV vaccine recall. METHODS Adolescent girls (N = 74) and their mothers independently completed questionnaires regarding HPV vaccination history, which were compared with medical chart data to assess the accuracy of HPV vaccine recall. RESULTS There were high levels of inaccuracy between actual HPV vaccination and self-report of vaccine receipt. Both mothers and daughters had poor recall of HPV vaccination, and were more likely to underestimate than overestimate the coverage. Girls who accurately reported their vaccination status were not more likely to have been sexually active in the past 2 months (p = .75). CONCLUSIONS These findings have clinical and research implications, as self-report is relied on to assess young womens vaccination status in research settings or in the absence of medical records. These data address the still prevalent concern that HPV vaccination encourages adolescent sexual behavior. It is unlikely that sexual behaviors will change as a result of vaccination in the large percentage of girls who cannot recall being vaccinated.

Population-Level Effects of Human Papillomavirus Vaccination Programs on Infections with Nonvaccine Genotypes

After introduction of vaccination, some prevalences of nonvaccine types changed, without clear evidence for type replacement.

Catching Up or Missing Out? Human Papillomavirus Vaccine Acceptability Among 18- to 26-Year-old Men Who Have Sex With Men in a US National Sample.

Background Men who have sex with men (MSM) are disproportionately affected by human papillomavirus (HPV)–related outcomes and would benefit from HPV vaccination in adolescence. We assessed HPV vaccine attitudes, uptake, and barriers in this high-risk young MSM (YMSM) population. Methods An online US sample of 1457 YMSM aged 18 to 26 years were recruited in December 2011 to examine HPV vaccine acceptability and uptake. The online survey included sociodemographics, HPV vaccine attitudes, acceptability, HPV vaccination status, health care use, and HPV knowledge. Results Despite high use of health care in the past year (86%) and high acceptability (87.8/100) for free HPV vaccine, only 6.8% had received one or more vaccine doses. In addition, only 4% of unvaccinated men had been offered the vaccine by their health care provider (HCP). In a multivariate regression of unvaccinated men, increased vaccine acceptability was associated with an HCP recommendation, worry about getting infected with HPV, and being tested for a sexually transmitted disease in the past year, whereas safety concerns, lower perceived risk of infection, and shame associated with HPV infection/disease were associated with decreased vaccine acceptability. Through logistic regression, vaccine uptake was associated with being tested for a sexually transmitted disease in the past year, disclosure of being gay or bisexual to a doctor, and greater HPV knowledge. Conclusions Health care providers need to use routine points of contact with YMSM patients to vaccinate against HPV. These data indicated missed opportunities to vaccinate YMSM who are open to HPV vaccination. In the future, HCPs of YMSM should be careful to avoid missed opportunities to vaccinate.

Factors Influencing Abstinence, Anticipation, and Delay of Sex Among Adolescent Boys in High–Sexually Transmitted Infection Prevalence Communities

PURPOSE Abstinence is a core pregnancy and sexually transmitted infection (STI) prevention strategy. We explore the attitudinal, behavioral, and family contexts relating to abstinence and the decision to delay sex among adolescent boys. METHODS Adolescent boys ages 14-17 years were recruited from community sites using a venue-based sampling method. All eligible boys at venues were invited to participate in an electronic survey. Question items included sexual behaviors, attitudes related to sex, relationships, masculine values, and family contextual items. RESULTS We enrolled 667 participants, mean age 15.7 years, of diverse ethnicity. A total of 252 were abstinent (38%). Abstinent participants were younger and less likely to report non-coital behaviors, and reported lower conventional masculine values. Among abstinent participants, 62% planned to delay sex, whereas 38% anticipated sex in the next year. Participants with lower conventional masculine values and more religious or moral motivations for abstinence were more likely to plan to delay sex. CONCLUSIONS Abstinence among boys is common, even in high-STI risk communities. For these boys, abstinence appears to be a complex behavioral decision influenced by demographic, behavioral, attitudinal, and contextual factors such as age, race, non-coital sexual behaviors, and masculine values. Understanding the attitudes and contexts of abstinence, including plans to delay sex, can inform the development of public health programs for early fatherhood and STI prevention.