Comparison of Female Genital Tract Cytokine and Microbiota Signatures Induced by Initiation of Intramuscular DMPA and NET-EN Hormonal Contraceptives - a Prospective Cohort Analysis.

Background: Cervicovaginal inflammation, bacterial microbiota and hormonal contraceptives all influence sexual and reproductive health. To date, the effects of intramuscular depo-medroxyprogesterone acetate (DMPA-IM) versus injectable norethisterone enanthate (NET-EN) on vaginal microbiota or cytokines have not been compared back-to-back, although in-vitro data suggest that DMPA-IM and NET-EN have different pharmacokinetic and biologic activities. This study aimed at comparing the effects of DMPA-IM versus NET-EN initiation on cervicovaginal cytokines and microbiota in women at high risk for sexually transmitted infections (STIs) assigned to the respective contraceptives. Methods: We collected socio-demographic characteristics and vaginal samples from women initiating DMPA-IM (ECHO Trial; n = 53) and NET-EN (UChoose Trial; n = 44) at baseline and after two consecutive injections to assess cytokine concentrations by Luminex, vaginal microbiota by 16S rRNA gene sequencing, STIs, bacterial vaginosis (BV) and candidiasis. Results: Cytokine concentrations did not change significantly after initiating DMPA-IM or NET-EN, although NET-EN versus DMPA-IM-associated profiles were distinct. While the abundance of bacterial taxa associated with optimal and non-optimal microbiota fluctuated with DMPA-IM use, overall community composition did not significantly change with either contraceptive. HSV-2 serology, chlamydial infection, gonorrhoea and candidiasis did not influence the associations between contraceptive type and cervicovaginal cytokines or microbiota. Conclusions: Both DMPA-IM and NET-EN use did not lead to broad inflammatory or microbiota changes in the female genital tract of sub-Saharan African women. This suggests that NET-EN is likely a viable option for contraception in African women at high risk of BV and STIs.

Mycoplasma genitalium Provokes Seminal Inflammation among Infertile Males.

The impact of sexually transmitted infections (STI) on male fertility is controversial. Aims: To investigate the prevalence of urethritis-associated STIs (chlamydia, gonorrhoeae, Mycoplasma genitalium, trichomoniasis) among infertile males; to analyze the effect of STIs on semen parameters and blood PSA. Case-control study. Study group (n = 2000): males with fertility problems or desire for fertility check. Control group (n = 248): male partners of pregnant women. Analyses: polymerase chain reaction for STI, seminal interleukin 6 (IL-6), semen and fractionated urine, blood analyses (PSA, reproductive hormones). The prevalence of M. genitalium and chlamydia in the study group was 1.1% and 1.2%, respectively. The prevalence of chlamydia in the control group was 1.6%, while there were no M. genitalium cases. No cases with gonorrhoeae or trichomoniasis or combined infections were observed in neither group. There was a higher seminal concentration of neutrophils and IL-6 among M. genitalium positives compared with STI negatives. There was a trend toward a lower total count of spermatozoa and progressive motility among STI positives. No impact of STIs on PSA was found. The prevalence of STIs among infertile males is low. M. genitalium is associated with seminal inflammation. The impact of STIs on semen parameters deserves further investigations.

Intrauterine device use, sexually transmitted infections, and fertility: a prospective cohort study.

BACKGROUND: In the 1970s, numerous medical reports, media coverage, and litigation around the Dalkon Shield intrauterine device led to a perception that all intrauterine devices cause upper genital tract infection and infertility. OBJECTIVE: This study aimed to assess the association between intrauterine device use and time to conception. STUDY DESIGN: The Fertility After Contraceptive Termination Study is a multicenter, prospective cohort study of women stopping their contraceptive method to attempt conception. We recruited participants between 2011 and 2017. Participants were a convenience sample of women recruited from academic centers in Philadelphia, PA; Los Angeles, CA; St. Louis, MO; Indianapolis, IN; Aurora, CO; and Salt Lake City, UT. Women were eligible if they stopped their contraceptive method within the past 120 days before enrollment, were between 18 and 35 years of age, had no history of infertility or sterilization, and had at least 6 months of follow-up. Baseline data included demographic and reproductive characteristics, past contraceptive use, nucleic acid amplification testing for sexually transmitted infections, and serology for past infection with Chlamydia trachomatis, Trichomonas vaginalis, and Mycoplasma genitalium. The primary exposure was intrauterine device use (ever); the primary outcome was time to conception. All participants were observed longitudinally for up to 24 months. We used piecewise exponential proportional hazards models with multiple imputation to provide hazard ratios and their respective 95% confidence intervals. RESULTS: Of the 461 participants, mean age was 28.2 years, 178 (38.7%) were Black, 157 (34.1%) were considered as low socioeconomic status, and 275 (59.7%) had a history of intrauterine device use. Without adjusting for any covariates, the median time to conception was shorter for participants who had a history of intrauterine device use (5.1 months) than participants who never used an intrauterine device (7.5 months). After controlling for potential confounders, the association of past intrauterine device use with time to conception was not statistically significant (adjusted hazard ratio, 1.25; 95% confidence interval, 0.99-1.58). In our multivariable model, age, nulligravidity, Black race, low socioeconomic status, and past Mycoplasma genitalium infection were associated with longer times to conception (hazard ratio, 0.76; 95% confidence interval, 0.58-0.99). Conception by 12 months was lower in participants with past Mycoplasma genitalium infection (68% vs 80% without past infection; P=.019). CONCLUSION: We found no impairment of fertility with ever use of an intrauterine device. Serologic evidence of past Mycoplasma genitalium infection was associated with longer times to conception and higher rates of infertility. Mycoplasma genitalium infection is a potential modifiable cause of infertility.

Protection and Risk: Male and Female Genital Microbiota and Sexually Transmitted Infections.

Unique compositional and functional features of the cervicovaginal microbiota have been associated with protection against and risk for sexually transmitted infections (STI). In men, our knowledge of the interaction between the penile microbiota and STI is less developed. The current state of our understanding of these microbiota and their role in select STIs is briefly reviewed, along with strategies that leverage existing findings to manipulate genital microbiota and optimize protection against STIs. Finally, we focus on major research gaps and present a framework for future studies.

Human alphaherpesvirus 2 (HSV-2) among female sex workers from Brazil: cross-sectional study using respondent-driven sampling.

OBJECTIVE: Female sex workers (FSWs) are vulnerable to human alphaherpesvirus 2 (HSV-2) infection due to their high numbers of sexual partners. The objective of this study was to evaluate the seroprevalence and risk behaviours associated with HSV-2. METHODS: A cross-sectional study was conducted in Mato Grosso do Sul, Brazil. A total of 376 FSWs were recruited by respondent-driven sampling (RDS) methodology and answered an epidemiological questionnaire. Blood samples were collected to test for HSV-2 antibodies using commercial ELISA and for HSV-2 DNA using real-time PCR. RESULTS: The seropositivity was 47.3% (178/376) for HSV-2 IgG and 10.1% (38/376) for HSV-2 IgM. HSV-2 viraemia was detected in two infected FSWs with primary infections. In bivariate and multivariate analyses, the OR for HSV-2 IgG increased with age (OR=2.53-7.90, OR=2.66-6.37) and the number of sexual partners (OR=2.30-3.25). On the other hand, daily alcohol consumption (OR=0.10) and the use of condoms during the last intercourse (OR=0.47) were protective factors against HSV-2 acquisition. CONCLUSION: Despite the impact of FSWs in public health policies with the dissemination of sexually transmitted infections, there have been few studies performed regarding the prevalence of HSV-2 in Brazil, making it difficult to implement any control or preventative measures. The results produced here using an RDS methodology demonstrated a high prevalence, risk behaviours and primary infection among the FSWs. These results reinforce the need to implement control and preventative measures for HSV-2 infection in this population.

What's Sex Got to Do With It? Understanding Potential Confounding and Exposure Misclassification in Mechanistic Sexually Transmitted Infection Research.

We conducted a prospective study of 13 heterosexual couples to understand the impact of recent condomless vaginal sex on vaginal immune marker measurement and potential exposure misclassification due to the presence of semen. All immune markers were detectable in semen and concentrations of vaginal immune markers varied by sex recency.

Impact of Helminth Infections on Female Reproductive Health and Associated Diseases.

A growing body of knowledge exists on the influence of helminth infections on allergies and unrelated infections in the lung and gastrointestinal (GI) mucosa. However, the bystander effects of helminth infections on the female genital mucosa and reproductive health is understudied but important considering the high prevalence of helminth exposure and sexually transmitted infections in low- and middle-income countries (LMICs). In this review, we explore current knowledge about the direct and systemic effects of helminth infections on unrelated diseases. We summarize host disease-controlling immunity of important sexually transmitted infections and introduce the limited knowledge of how helminths infections directly cause pathology to female reproductive tract (FRT), alter susceptibility to sexually transmitted infections and reproduction. We also review work by others on type 2 immunity in the FRT and hypothesize how these insights may guide future work to help understand how helminths alter FRT health.

Deep Sequencing Reveals Compartmentalized HIV-1 in the Semen of Men with and without Sexually Transmitted Infection-Associated Urethritis.

Concurrent sexually transmitted infections (STI) can increase the probability of HIV-1 transmission primarily by increasing the viral load present in semen. In this study, we explored the relationship of HIV-1 in blood and seminal plasma in the presence and absence of urethritis and after treatment of the concurrent STI. Primer ID deep sequencing of the V1/V3 region of the HIV-1 env gene was done for paired blood and semen samples from antiretroviral therapy (ART)-naive men living in Malawi with (n = 19) and without (n = 5) STI-associated urethritis; for a subset of samples, full-length env genes were generated for sequence analysis and to test entry phenotype. Cytokine concentrations in the blood and semen were also measured, and a reduction in the levels of proinflammatory cytokines was observed following STI treatment. We observed no difference in the prevalence of diverse compartmentalized semen-derived lineages in men with or without STI-associated urethritis, and these viral populations were largely stable during STI treatment. Clonal amplification of one or a few viral sequences accounted for nearly 50% of the viral population, indicating a recent bottleneck followed by limited viral replication. We conclude that the male genital tract is a site where virus can be brought in from the blood, where localized sustained replication can occur, and where specific genotypes can be amplified, perhaps initially by cellular proliferation but further by limited viral replication.IMPORTANCE HIV-1 infection is a sexually transmitted infection that coexists with other STI. Here, we examined the impact of a concurrent STI resulting in urethritis on the HIV-1 population within the male genital tract. We found that viral populations remain largely stable even with treatment of the STI. These results show that viral populations within the male genital tract are defined by factors beyond transient inflammation associated with a concurrent STI.

Aberrant cervical innate immunity predicts onset of dysbiosis and sexually transmitted infections in women of reproductive age.

Sexually transmitted infections (STIs) and vaginal dysbiosis (disturbed resident microbiota presenting with abnormal Nugent score or candidiasis) have been associated with mucosal inflammation and risk of HIV-1 infection, cancer and poor reproductive outcomes. To date, the temporal relationships between aberrant cervical innate immunity and the clinical onset of microbial disturbance have not been studied in a large population of reproductive age women. We examined data from a longitudinal cohort of 934 Ugandan and Zimbabwean women contributing 3,274 HIV-negative visits who had complete laboratory, clinical and demographic data. Among those, 207 women later acquired HIV, and 584 women were intermittently diagnosed with C. trachomatis (CT), N. gonorrhoeae (NG), genital herpes (HSV-2), T. vaginalis (TV), candidiasis, and abnormal intermediate (4-6) or high (7-10) Nugent score, i.e. bacterial vaginosis (BV). Immune biomarker concentrations in cervical swabs were analyzed by generalized linear and mixed effect models adjusting for site, age, hormonal contraceptive use (HC), pregnancy, breastfeeding, genital practices, unprotected sex and overlapping infections. High likelihood ratios (1.5-4.9) denoted the values of cervical immune biomarkers to predict onset of abnormal Nugent score and candidiasis at the next visits. When controlling for covariates, higher levels of ß-defensin-2 were antecedent to BV, CT and HSV-2, lower anti-inflammatory ratio IL-1RA:IL-1ß-to intermediate Nugent scores and candida, lower levels of the serine protease inhibitor SLPI-to candida, lower levels of the adhesion molecule ICAM-1 -to TV, and lower levels of the oxidative stress mitigator and endothelial activation marker VEGF-to NG. Changes in innate immunity following onset of dysbiosis and infections were dependent on HC use when controlling for all other covariates. In conclusion, imminent female genital tract dysbiosis or infection can be predicted by distinct patterns of innate immunity. Future research should characterize biotic and abiotic determinants of this pre-existing innate immunity state.

Bivalent Vaccine Effectiveness Against Anal Human Papillomavirus Positivity Among Female Sexually Transmitted Infection Clinic Visitors in the Netherlands.

Human papillomavirus (HPV) vaccines are indicated for anal cancer prevention, but evidence for vaccine effectiveness (VE) against anal HPV infections among women is limited. We estimated the VE (≥1 dose) against anal HPV positivity of the bivalent vaccine, whose target types HPV-16/18 are associated with approximately 90% of HPV-related anal cancers. Among 548 female STI clinic visitors 16-24 years old who provided an anal swab sample as part of a repeated cross-sectional survey, VE against HPV-16/18 was 89.9% (95% confidence interval, 63.0%-97.2%). Type-specific VE correlated well with VE against cervicovaginal HPV (Spearman ρ = 0.76), suggesting comparable effectiveness of HPV-16/18 vaccination against genital and anal infections.

Mechanisms of sexually transmitted infection-induced inflammation in women: implications for HIV risk.

INTRODUCTION: Globally, sexually transmitted infections (STI) affect >300 million people annually, and are a major cause of sexual and reproductive health complications in women. In this commentary, we describe how STIs interact with the immune and non-immune cells, both within and below the cervicovaginal mucosal barrier, to cause inflammation, which in turn has been associated with increased HIV acquisition risk. DISCUSSION: STIs have a major impact on the female genital mucosa, which is an important biological and physical barrier that forms the first line of defence against invading microorganisms such as HIV. Pattern recognition of STI pathogens, by receptors expressed either on the cell surface or inside the cell, typically triggers inflammation at the mucosal barrier. The types of mucosal responses vary by STI, and can be asymptomatic or culminate in the formation of discharge, ulcers and/or warts. While the aim of this response is to clear the invading microbes, in many cases these responses are either evaded or cause pathology that impairs barrier integrity and increases HIV access to target cells in the sub-mucosa. In addition, innate responses to STIs can result in an increased number of immune cells, including those that are the primary targets of HIV, and may contribute to the association between STIs and increased susceptibility to HIV acquisition. Many of these cells are mediators of adaptive immunity, including tissue-resident cells that may also display innate-like functions. Bacterial vaginosis (BV) is another common cause of inflammation, and evidence for multiple interactions between BV, STIs and HIV suggest that susceptibility to these conditions should be considered in concert. CONCLUSIONS: STIs and other microbes can induce inflammation in the genital tract, perturbing the normal robust function of the mucosal barrier against HIV. While the impact of STIs on the mucosal immune system and HIV acquisition is often under-appreciated, understanding their interactions of the infections with the immune responses play an important role in improving treatment and reducing the risk of HIV acquisition. The frequent sub-clinical inflammation associated with STIs underscores the need for better STI diagnostics to reverse the immunological consequences of infection.

Chronic immune barrier dysregulation among women with a history of violence victimization.

We explored the association between violence victimization and increased risk for acquiring sexually transmitted infections (STIs) in women by measuring cellular immune barrier properties from the female reproductive tract. STI-negative participants reporting repeated prior victimization occurrences through the lifetime trauma and victimization history (LTVH) instrument were more likely to exhibit alterations in barrier homeostasis and the composition of critical immune mediators irrespective of demographic parameters or presence of bacterial vaginosis. By combining cellular data with mixed-effect linear modeling, we uncovered differences in local T cells, MHCII+ antigen-presenting cells, and epithelial cells indicative of altered trafficking behavior, increased immunosuppressive function, and decreased barrier integrity at sites of STI exposure that correlate most strongly with LTVH score. These data evidence a biological link between a history of violence victimization and risk of STI acquisition through immune dysregulation in the female reproductive tract.

HIV-1 exposure and immune activation enhance sexual transmission of Hepatitis C virus by primary Langerhans cells.

INTRODUCTION: The significant rise in incidence of Hepatitis C virus (HCV) infection among men-who-have-sex-with-men (MSM) living with HIV-1 suggests that HCV under specific circumstances is transmitted via sexual contact. During sexual transmission HCV has to cross the epithelial barrier to either directly enter the blood stream or indirectly via mucosal immune cells. However, the mechanisms of sexual transmission of HCV remain unclear. We investigated the role of Langerhans cells (LCs) in HCV susceptibility during sexual contact as LCs are among the first cells in mucosal tissues to encounter invading viruses. METHODS: We investigated the phenotype of primary LCs in anal biopsies from MSM living with HIV-1. To investigate the role of primary LCs in HCV infection and transmission, we have used both isolated primary skin LCs and the ex vivo tissue transmission model. RESULTS: Our data identified an important role for mucosal LCs in facilitating HCV transmission after HIV-1 exposure or immune activation. LCs were detected within mucosal anal tissues obtained from HIV-1 positive MSM biopsies. In order to perform functional studies, we used primary LCs from skin, which have a similar phenotype as mucosal LCs. Immature LCs were neither infected nor transmitted HCV to hepatocytes. Notably, exposure to HIV-1 significantly increased HCV transmission by LCs in the ex vivo transmission model. HIV-1 replication was crucial for the increased HCV transmission as HIV-1 inhibitors significantly reduced HIV-1-induced HCV transmission. Moreover, tissue immune activation of LCs also increased HCV transmission to target cells. CONCLUSIONS: Thus, our data strongly indicate that HIV-1 or immune activation in MSM leads to capture of HCV by mucosal LCs, which might facilitate transmission to other cells or allow entry of HCV into the blood. This novel transmission mechanism by LCs also implicates that the activation state of LCs is an important cellular determinant for HCV susceptibility after sexual contact.

Semen quality is affected by HLA class I alleles together with sexually transmitted diseases.

BACKGROUND: The human leukocyte antigen (HLA) locus includes several genes with key roles in antigen presentation and immune response, some of them inclusively found to be associated with non-obstructive azoospermia. Still, HLA connections to other infertility phenotypes such as semen hyperviscosity (SHV), asthenozoospermia (AST), and oligozoospermia (OLI) have been often neglected. OBJECTIVES: In this work, we aimed to evaluate the association of HLA class I and II genes with SHV, AST, and OLI phenotypes while exploring a possible role in an adaptive immune response to sexually transmitted diseases (STD). MATERIALS AND METHODS: Whole-exome sequencing was performed in a Portuguese cohort of 71 infertility cases and 68 controls, followed by HLA typing using a specific software-HLA*PRG:LA tool. Molecular screenings of seven STD were carried out in a subset of 72 samples (30 cases and 42 controls). RESULTS: Statistical tests uncovered three protective alleles: HLA-A*11:01, associated with all forms of male infertility (p = 0.0006); HLA-DQB1*03:02 with SHV and OLI (PSHV  = 0.0303, POLI  = 0.0153); and HLA-A*29:02 with OLI (p = 0.0355), which was found to interfere in sperm number together with HPV (p = 0.0313). Five risk alleles were also identified: two linked with SHV (HLA-B*50:01, p = 0.0278; and HLA-C*06:02, p = 0.0461), another one with both SHV and OLI (HLA-DQA1*05:01, PSHV  = 0.0444 and POLI =0.0265), and two with OLI (HLA-C*03:03, p = 0.0480; and HLA-DQB1*03:01, p = 0.0499). Here, HLA-C*03:03 carriers tend to be HPV infected. CONCLUSIONS: The application of HLA*PRG:LA tool to the study of male infertility provided novel insights for an HLA correlation with semen quality, namely among SHV and OLI phenotypes. The discovery of an HLA-A*29:02/HPV crosstalk, together with former reports of HLA alleles conferring resistance-susceptibility to diverse human pathogens, raises the hypothesis of a mechanistic link between male infertility, HLA polymorphism, and host response to STD.

Trichomonas vaginalis and Mycoplasma hominis: new tales of two old friends.

Trichomonas vaginalis is an anaerobic protist, responsible for the most prevalent non-viral sexually transmitted infection in humans. One of the most intriguing aspects of T. vaginalis pathobiology is the complex relationship with intracellular microbial symbionts: a group of dsRNA viruses belonging to family of Totiviridae (T. vaginalis virus), and eubacteria belonging to the Mycoplasma genus, in particular Mycoplasma hominis. Both microorganisms seem to strongly influence the lifestyle of T. vaginalis, suggesting a role of the symbiosis in the high variability of clinical presentation and sequelae during trichomoniasis. In the last few years many aspects of this unique symbiotic relationship have been investigated: M. hominis resides and replicates in the protozoan cell, and T. vaginalis is able to pass the bacterial infection to both mycoplasma-free protozoan isolates and human epithelial cells; M. hominis synergistically upregulates the proinflammatory response of human monocytes to T. vaginalis. Furthermore, the influence of M. hominis over T. vaginalis metabolism and physiology has been characterized. The identification of a novel species belonging to the class of Mollicutes (Candidatus Mycoplasma girerdii) exclusively associated to T. vaginalis opens new perspectives in the research of the complex series of events taking place in the multifaceted world of the vaginal microbiota, both under normal and pathological conditions.

Immunological Methods for Treatment of Vulvovaginal Infections in the Preconception Period.

Traditional therapy and extensive use of medications and intravaginal autolymphocyte therapy show different results of the treatment of vulvovaginal infections. The purpose of the article was to explore safe and highly effective methods to treat vulvovaginal infections and diseases of the pelvic organs. The standard clinical and laboratory screening of 70 patients of reproductive age was carried out to diagnose the diseases of the reproductive tract. The screening included the description of quantitative and qualitative characteristics of vaginal discharge, examining the mucous covering of the vulva and vagina, microscopic examination of Gram-stained vaginal swabs, endocervical cultures, and diagnosis of sexually transmitted infections using polymerase chain reaction. Intravaginal autolymphocyte therapy was used together with traditionally-accepted treatment schemes (etiotropic antibacterial and antifungal therapy) in the treatment of the main group (40 patients). Traditional treatment methods depending on the etiology of the development of infection were used in the control group (30 patients). The IgM, IgA, and IgG levels were also observed because of the possibility of causing embryo rejection. This study shows that in case of relapsing vulvovaginitis and mixed infections accompanied by disorders of the immune system at different levels, the use of intravaginal autolymphocyte therapy in a comprehensive therapy can be assessed as advisable and pathogenetically substantiated.

Seropositivity to Multiple Anogenital Human Papillomavirus (HPV) Types Is Associated With Current Anogenital HPV Infection, Abnormal Cytology, and Seropositivity for Nongenital HPVs.

Background: Antibodies against human papillomaviruses (HPVs) are biomarkers for current or past infections. We assessed whether antibodies against multiple HPV types were determinants of current multiple anogenital HPV infections, abnormal cytology, and seropositivity for cutaneous HPVs. Methods: A total of 1848 Slovenian women attended 2 rounds of cervical cancer screening 3 years apart and provided data on HPV antibodies and HPV DNA at both visits. Antibodies against 15 anogenital HPV types and 6 cutaneous HPVs were determined using pseudovirion-Luminex serology and anogenital HPV DNA using Linear Array. Antibodies to polyomaviruses were evaluated as a control. Women were grouped as either HPV seronegative or having antibodies to 1-2 HPV types or to ≥3 HPV types. Results: Presence of antibodies to multiple anogenital HPV types at baseline was associated strongly with (i) presence of HPV DNA at the cervix (χ2 = 68.8; P < .0001), (ii) multiple types of HPV DNA at baseline (χ2 = 58.6; P < .0001), (iii) HPV DNA at follow-up (χ2 = 22.9; P < .0001), (iv) abnormal cytology (χ2 = 9.8; P = .0017), and (v) concomitant presence of antibodies to any of 6 nongenital HPV types (χ2 = 40.1; P < .0001). Presence of antibodies to ≥3 anogenital HPV types tended to persist over time. Conclusions: Seropositivity against at least 3 anogenital HPV types is associated with current multiple anogenital HPV infections, abnormal cytology, and seropositivity to nongenital HPVs.

Assessment of herd effects among women and heterosexual men after girls-only HPV16/18 vaccination in the Netherlands: A repeated cross-sectional study.

Data on the impact of human papillomavirus (HPV) vaccination on the population HPV prevalence are largely obtained from women. We assessed the impact of the girls-only HPV16/18 vaccination program in the Netherlands that started in 2009, on trends in HPV prevalence among women and heterosexual men, using data from the PASSYON study. In this cross-sectional study, the HPV prevalence among 16- to 24-year-old visitors to sexually transmitted infection clinics was assessed in 2009, 2011, 2013, and 2015. We compared the genital postvaccination HPV prevalence with the prevaccination prevalence (2009) using Poisson GEE models. In total, we included 4,996 women and 1,901 heterosexual men. The percentage of women who reported to be vaccinated increased from 2.3% in 2009 to 37% in 2015. Among all women, the HPV16/18 prevalence decreased from 23% prevaccination to 15% in 2015 (adjusted prevalence ratio [aPR] 0.62, ptrend < 0.01). Among heterosexual men, the HPV16/18 prevalence decreased from 17% prevaccination to 11% in 2015 (aPR 0.52, ptrend < 0.01). Of the heterosexual men with a steady partner, HPV16/18 prevalence was lower among those whose steady partner had been vaccine-eligible in the national immunization program (aPR 0.13). Among unvaccinated women, the HPV16/18 prevalence in 2015 was not different from prevaccination. The decreasing HPV16/18 prevalence among heterosexual men and the reduced HPV16/18 prevalence among heterosexual men with a vaccine-eligible steady partner strongly suggests herd protection from girls-only vaccination. Absence of notable herd effects among unvaccinated women 6 years postvaccination may be due to the moderate vaccine uptake among girls in the Netherlands.