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Background: Oral human papillomavirus (HPV) infections are a leading cause of oropharyngeal cancers. In 2015 and 2016, HPV vaccines became publicly funded for gay, bisexual, and other men who have sex with men (GBM) under 27 years of age in most Canadian provinces., Methods: Between 2017 and 2019, sexually-active GBM in Montreal, Toronto, and Vancouver were recruited through respondent-driven sampling. Participants aged 16 to 30 years were invited to self-collect oral rinse specimens for HPV testing. We estimated HPV prevalence in the oral tract overall and compared these by vaccination status., Results: Among the 838 GBM with a valid oral specimen, 36.9% reported receiving ≥1 dose of HPV vaccine. Overall, oral HPV prevalence was 2.6% (95% confidence interval, CI: 1.5, 3.7%) for at least one HPV type and 1.2% (95% CI: 0.5, 1.9%) for any high-risk type. We detected quadrivalent (HPV 6/11/16/18) vaccine-preventable types in 0.3% (95% CI: 0.0, 1.0%) of vaccinated individuals and 1.1% (95% CI: 0.1, 2.0%) in unvaccinated individuals., Conclusions: Oral HPV prevalence was low in a population of young urban GBM in Canada of whom 37% were vaccinated. Findings serve as a benchmark for monitoring of vaccination impacts on oral HPV infection within this priority population., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Background: Understanding the natural history of human papillomavirus (HPV) infections is essential to cervical cancer prevention planning. We estimated HPV type-specific infection detection and clearance in young women., Methods: The HPV Infection and Transmission among Couples through Heterosexual activity (HITCH) study is a prospective cohort of 502 college-age women who recently initiated a heterosexual relationship. We tested vaginal samples collected at 6 clinical visits over 24 months for 36 HPV types. Using rates and Kaplan-Meier analysis, we estimated time-to-event statistics with 95% confidence intervals (CIs) for detection of incident infections and clearance of incident and present-at-baseline infections (separately). We conducted analyses at the woman- and HPV-levels, with HPV types grouped by phylogenetic relatedness., Results: By 24 months, we detected incident infections in 40.4% (CI, 33.4%-48.4%) of women. Incident subgenus 1 (43.4; CI, 33.6-56.4), 2 (47.1; CI, 39.9-55.5), and 3 (46.6; CI, 37.7-57.7) infections cleared at similar rates per 1000 infection-months. We observed similar homogeny in HPV-level clearance rates among present-at-baseline infections., Conclusions: Our analyses provide type-specific infection natural history estimates for cervical cancer prevention planning. HPV-level analyses did not clearly indicate that high oncogenic risk subgenus 2 infections persist longer than their low oncogenic risk subgenera 1 and 3 counterparts., Competing Interests: Potential conflicts of interest. M. Z. and E. L. F. hold a patent related to the discovery “DNA methylation markers for early detection of cervical cancer,” registered at the Office of Innovation and Partnerships, McGill University, Montréal, Québec, Canada, October 2018. A provisional utility patent application before the United States Patent and Trademark Office was also filed (November 2018) and a patent cooperation treaty application (PCT/IB2020/050885), filed in February 2020, has been published (No. WO 2020/115728; June 2020). E. L. F. reports grants and personal fees from Merck outside of the submitted work. F. C. reports grants from Réseau FRQS-SIDA during the conduct of the study, and grants to his institution for HPV-related work from Merck Sharp and Dome, Roche Diagnostics, and Becton Dickinson outside of the submitted work. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Real-world evidence of human papillomavirus (HPV) vaccine effectiveness (VE) against longitudinal outcomes is lacking among gay, bisexual, and other men who have sex with men (GBM). We compared 12-month incidence and persistence of anal HPV infection between vaccinated and unvaccinated GBM., Methods: We recruited GBM aged 16-30 years in Montreal, Toronto, and Vancouver, Canada, from 2017 to 2019. Participants were followed over a median of 12 months (interquartile range, 12-13 months). Participants self-reported HPV vaccination and self-collected anal specimens for HPV DNA testing. We calculated prevalence ratios (PR) for 12-month cumulative incidence and persistence with ≥1 quadrivalent vaccine type (HPV 6/11/16/18) between vaccinated (≥1 dose at baseline) and unvaccinated participants using a propensity score-weighted, modified Poisson regression., Results: Among 248 participants, 109 (44.0%) were vaccinated at baseline, of whom 62.6% received 3 doses. PRs for HPV 6/11/16/18 were 0.56 (95% confidence interval [CI], .24-1.31) for cumulative incidence and 0.53 (95% CI, .25-1.14) for persistence. PRs were 0.23 (95% CI, .05-1.03) and 0.08 (95% CI, .01-.59) for incidence and persistence, respectively, among participants who received their first dose at age ≤23 years and 0.15 (95% CI, .03-.68) and 0.12 (95% CI, .03-.54) among participants who were sexually active for ≤5 years before vaccination., Conclusions: Findings support national recommendations for HPV vaccination at younger ages or soon after sexual debut., Competing Interests: Potential conflicts of interest. J. C. declares research funding from ViiV Healthcare and Gilead Sciences; and remuneration for advisory work from ViiV Healthcare, Gilead Sciences, and Merck Canada. F. C. received grants paid to the institution for research projects from Roche Diagnostics, Becton Dickinson, and Merck Sharp and Dome; honorariums for presentations from Merck Sharp and Dome and Roche diagnostics; and has participated in an expert group for Merck Sharp and Dome. C. S. received grants paid to the institution for clinical trials and epidemiological studies funded by nonprofit organizations Ministère de la Santé et des Services Sociaux in Québec, Bill and Melinda Gates Foundation, and Michael Smith Foundation. D. H. S. T. received grants paid to the institution for investigator-initiated research from Abbvie, Gilead, and ViiV Healthcare; and D. H. S. T.'s institution has received support for industry-sponsored clinical trials from Glaxo Smith Kline. S. L. D. is the current Chair of the National Advisory Committee on Immunization. C. S. is a member of the Québec Immunization Committee. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Background: Humoral immune responses may be critical for preventing, controlling, and/or eliminating human papillomavirus (HPV) infection. We analyzed humoral response to natural HPV infection considering phylogenetic relatedness among unvaccinated women., Methods: We included 399 young women attending university/college in Montreal, Canada who were participants of the HITCH cohort. Participants provided blood samples at baseline and 5 follow-up visits. Antibody response to bacterially expressed L1 and E6 glutathione S-transferase (GST) fusion proteins, and virus-like particles (VLP-L1) of Alphapapillomavirus types were measured using multiplex serology. We assessed correlations and associations between HPV types at baseline using Pearson correlation coefficients (r) and univariable linear regressions., Results: At baseline, > 40% were seropositive for GST-L1 antibodies of at least 1 HPV type. Strong correlations between GST-L1 were observed for α9 HPV types: 58-52 (r = 0.86), 58-33 (r = 0.75), 33-52 (r = 0.72), and between GST-E6: 52-11 (r = 0.84), 52-18 (r = 0.79), 58-33 (r = 0.78), 35-11 (r = 0.76). HPV16 VLP-L1 moderately explained variability in HPV16 GST-L1 (regression coefficient [b] = 0.38, R2 = 43.1%), and HPV45 GST-L1 in HPV18 GST-L1 (b = 0.68, R2 = 42.8%). GST-E6 antibodies accounted for a low to moderate proportion of variability in HPV16 and HPV18 GST-E6 (R2 = 6.4%-62.2%)., Conclusions: Associations between naturally induced HPV-specific antibodies depend on phylogenetic relatedness., Competing Interests: Potential conflicts of interest . E. L. F. has served as an occasional advisor to companies involved with human papillomavirus (HPV) diagnostics (Roche, BD, Qiagen, Gen-Probe) and HPV vaccines (Merck, GSK); and his institution has received unconditional grants from Merck in aid of investigator-initiated studies. M. Z. and E. L. F. hold a patent related to the discovery “DNA methylation markers for early detection of cervical cancer”, registered at the Office of Innovation and Partnerships, McGill University, Montreal, Quebec, Canada (October 2018). F. C. has received grants or free reagents through his institution from Merck Sharp and Dohme, Becton Dickinson, and Roche; and honoraria from Merck and Roche for lectures on HPV. T. W. serves on advisory boards for MSD (Merck) Sharp & Dohme. M. D. W. is currently a senior medical writer at Certara Synchrogenix consulting services. None of the work presented in this manuscript was paid for or influenced by Certara Synchrogenix. All other authors report no potential conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Previous studies examining the association between male circumcision (MC) and human papillomavirus (HPV) infections have reported inconsistent results. We used data from the HPV Infection and Transmission Among Couples Through Heterosexual Activity (HITCH) cohort study to examine the association between MC and HPV infections in males and their female sexual partners., Methods: We enrolled monogamous couples in a longitudinal study between 2005 and 2011 in Montreal, Canada. We used logistic and Poisson regression models with propensity score adjustment to estimate odds ratios (ORs) and rate ratios for the association between MC and the prevalence, transmission, and clearance of HPV infections., Results: Four hundred thirteen couples were included in our study. The prevalence OR for the association between MC and baseline infections was 0.81 (95% confidence interval [CI], .56-1.16) in males and 1.05 (95% CI, .75-1.46) in females. The incidence rate ratio for infection transmission was 0.59 (95% CI, .16-2.20) for male-to-female transmission and 0.77 (95% CI, .37-1.60) for female-to-male transmission. The clearance rate ratio for clearance of infections was 0.81 (95% CI, .52-1.24)., Conclusions: We found little evidence of an association between MC and HPV infection prevalence, transmission, or clearance in males and females. Further longitudinal couple-based studies are required to investigate this association., Competing Interests: Potential conflicts of interest. E. L. F. and M. Z. hold a patent related to the discovery “DNA methylation markers for early detection of cervical cancer,” registered at the Office of Innovation and Partnerships, McGill University, Montreal, Quebec, Canada (October 2018). F. C. has received grants through his institution from Merck, Becton Dickinson, and Roche, as well as honoraria from Merck and Roche for lectures on HPV. All other authors report no potential conflicts of interest.. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Infections with human papillomaviruses (HPVs) may enter a latent state, and eventually become reactivated following loss of immune control. It is unclear what proportion of incident HPV detections are reactivations of previous latent infections vs new transmissions., Methods: The HPV Infection and Transmission among Couples through Heterosexual activity (HITCH) cohort study prospectively followed young newly formed heterosexual partners recruited between 2005 and 2011 in Montréal, Canada. We calculated the fraction of incident HPV detections nonattributable to sexual transmission risk factors with a Bayesian Markov model. Results are the median (2.5th-97.5th percentiles) of the estimated posterior distribution., Results: A total of 544 type-specific incident HPV detection events occurred in 849 participants; 33% of incident HPV detections occurred in participants whose HITCH partners were negative for that HPV type and who reported no other sex partners over follow-up. We estimate that 43% (38%-48%) of all incident HPV detections in this population were not attributable to recent sexual transmission and might be potentially reactivation of latent infections., Conclusions: A positive HPV test result in many cases may be a reactivated past infection, rather than a new infection from recent sexual behaviors or partner infidelity. The potential for reactivation of latent infections in previously HPV-negative women should be considered in the context of cervical cancer screening., Competing Interests: Potential conflicts of interests. F. C. reports grants paid to his institution from Becton Dickinson, Roche Molecular systems, and Merk Sharp and Dome outside of the submitted work, as well as from Canadian Institutes of Health Research (CIHR), CANFAR and the Fonds de la recherche en Santé du Québec. E. L. F. reports grants to his institution from CIHR, the National Institutes of Health, and Merck during the conduct of the study; and personal fees from Merck. M. Z. and E. L. F. hold a patent related to the discovery “DNA methylation markers for early detection of cervical cancer” registered at the Office of Innovation and Partnerships, McGill University, Montreal, Quebec, Canada. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: We implemented an opt-out clinic-based intervention pairing syphilis tests with routine human immunodeficiency virus (HIV) viral load testing. The primary objective was to determine the degree to which this intervention increased the detection of early syphilis., Methods: The Enhanced Syphilis Screening Among HIV-Positive Men (ESSAHM) Trial was a stepped wedge cluster-randomized controlled trial involving 4 urban HIV clinics in Ontario, Canada, from 2015 to 2017. The population was HIV-positive adult males. The intervention was standing orders for syphilis serological testing with viral loads, and control was usual practice. We obtained test results via linkage with the centralized provincial laboratory and defined cases using a standardized clinical worksheet and medical record review. We employed a generalized linear mixed model with a logit link to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of the intervention., Results: A total of 3895 men were followed over 7471 person-years. The mean number of syphilis tests increased from 0.53 to 2.02 tests per person per year. There were 217 new diagnoses of syphilis (control, 81; intervention, 136), for which 147 (68%) were cases of early syphilis (control, 61 [75%]; intervention, 86 [63%]). The annualized proportion with newly detected early syphilis increased from 0.009 to 0.032 with implementation of the intervention; the corresponding time-adjusted OR was 1.25 (95% CI, .71-2.20)., Conclusions: The implementation of standing orders for syphilis testing with HIV viral loads was feasible and increased testing, yet produced less-than-expected increases in case detection compared to past uncontrolled pre-post trials., Clinical Trials Registration: NCT02019043., (© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: We assessed the association between serum 25-hydroxyvitamin D levels and genital human papillomavirus (HPV) prevalence, incidence, and clearance among female participants in the HPV Infection and Transmission among Couples through Heterosexual activity (HITCH) Cohort Study., Methods: We genotyped HPV DNA in vaginal samples and quantified baseline serum 25-hydroxyvitamin D levels using Roche's Linear Array and Total vitamin D assay, respectively. We used logistic and Cox proportional hazards models, respectively, to estimate adjusted odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs)., Results: There was no association between vitamin D levels (every 10-ng/mL increase) at baseline and HPV prevalence (OR, 0.88; 95% CI, .73-1.03) or incidence (HR, 0.88; 95% CI, .73-1.06), but we observed a modest negative association with HPV clearance (HR, 0.76; 95% CI, .60-.96). Vitamin D levels <30 ng/mL, compared with those ≥30 ng/mL, were not associated with HPV prevalence (OR, 0.98; 95% CI, .57-1.69) or incidence (HR, .87; 95% CI, .50-1.43), but they were associated with a marginally significant increased clearance (OR, 2.14; 95% CI, .99-4.64). We observed consistent results with restricted cubic spline modeling of vitamin D levels and clinically defined categories. HPV type-specific analyses accounting for multiple HPV infections per participant showed no association between vitamin D levels and all study outcomes., Conclusions: This study provided no evidence of an association between low vitamin D levels and increased HPV prevalence, acquisition, or clearance., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Using cross-sectional survey data (Engage, 2017-2018) from 1,137 men who have sex with men, ≥16 years old, in Montreal, we compared observed human immunodeficiency virus (HIV) seroconcordance in previous-6-months' sexual partnerships with what would have been observed by chance if zero individuals serosorted. Of 5 recent partnerships where both individuals were HIV-negative, we compared observed concordance in preexposure prophylaxis (PrEP) use with the counterfactual if zero individuals selected partners based on PrEP use. We estimated the concordance by chance using a balancing-partnerships approach assuming proportionate mixing. HIV-positive respondents had a higher proportion of HIV-positive partners (66.4%, 95% confidence interval (CI): 64.0, 68.6) than by chance (23.9%, 95% CI: 23.1, 24.7). HIV-negative respondents (both on and not on PrEP) had higher proportions of HIV-negative partners (82.9% (95% CI: 81.1, 84.7) and 90.7% (95% CI: 89.6, 91.7), respectively) compared with by chance (76.1%, 95% CI: 75.3, 76.9); however, those on PrEP had a higher proportion of HIV-positive partners than those not on PrEP (17.1% (95% CI: 15.3, 18.9) vs. 9.3% (95% CI: 8.3, 10.4). Those on PrEP also had a higher proportion of partners on PrEP among their HIV-negative partners (50.6%, 95% CI: 42.5, 58.8) than by chance (28.5%, 95% CI: 27.5, 29.4). The relationship between PrEP and sexual-mixing patterns demonstrated by less population-level serosorting among those on PrEP and PrEP-matching warrants consideration during PrEP roll-out., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.)

Background: We studied the association between human papillomavirus (HPV) viral load (VL) and HPV concordance., Methods: The HITCH cohort study included young, heterosexual, recently formed, sexually active couples. Questionnaires and genital samples were collected at 0 and 4 months. Samples were tested for HPV DNA by polymerase chain reaction (PCR; Linear Array). VLs of HPV6/11/16/18/31/42/51 were quantified using type-specific real-time PCR. Correlations between VL and type-specific HPV prevalence and incidence were evaluated using multilevel, mixed-effects linear/logistic regression models., Results: We included 492 couples. VLs were higher in penile than vaginal samples. VL at subsequent visits correlated significantly within men (r, 0.373), within women (r, 0.193), and within couples (r range: 0.303-0.328). Men with high VL had more type-specific persistent HPV infections (odds ratio [OR], 4.6 [95% confidence interval {CI}, 2.0-10.5]). High VL in men was associated with prevalent (OR, 5.3 [95% CI, 2.5-11.2]) and incident (OR, 6.7 [95% CI, 1.5-30.7]) type-specific HPV infections in their partner. Women's VL was associated with type-specific HPV prevalence in their partner at the same (OR, 5.9) and subsequent (OR, 4.7) visit., Conclusions: Persistent HPV infections have limited VL fluctuations. VL between sex partners are correlated and seem predictive of transmission episodes., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Detection of human papillomavirus (HPV) DNA in genital samples may not always represent true infections but may be depositions from infected sexual partners. We examined whether sexual risk factors and a biomarker (Y chromosome DNA) were associated with genital HPV partner concordance and estimated the fraction of HPV detections potentially attributable to partner deposition., Methods: The HITCH study enrolled young women attending a university or college in Montréal, Canada, and their male partners, from 2005 to 2010. We tested baseline genital samples for Y chromosome DNA and HPV DNA using polymerase chain reaction., Results: Type-specific HPV concordance was 42.4% in partnerships where at least one partner was HPV DNA positive. Y chromosome DNA predicted type-specific HPV concordance in univariate analyses, but in multivariable models the independent predictors of concordance were days since last vaginal sex (26.5% higher concordance 0-1 vs 8-14 days after last vaginal sex) and condom use (22.6% higher concordance in never vs always users). We estimated that 14.1% (95% confidence interval [CI], 6.3-21.9%) of HPV DNA detections in genital samples were attributable to vaginal sex in the past week., Conclusions: A substantial proportion of HPV DNA detections may be depositions due to recent unprotected vaginal sex., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: The risk of anal cancer due to high-risk human papillomavirus (HR-HPV) is higher in women living with human immunodeficiency virus (HIV) than in the general population. We present findings of cervical and anal HPV and cytologic tests at baseline in the EVVA cohort study and HPV persistence data 6 months after baseline., Methods: Semiannual visits included questionnaires, chart reviews, cervical/anal cytologic and cervical/anal HPV testing for 2 years. Genotyping for 36 HPV genotypes was performed using the Roche Linear Array HPV genotyping test., Results: A total of 151 women living with HIV were recruited. At baseline, 75% had anal HPV, 51% had anal HR-HPV, 50% had cervical HPV, and 29% had cervical HR-HPV. Anal HPV-16 and HPV-51 were more frequent in women born in Canada (31% and 29%, respectively, compared with ≤16% for other women). Most anal HR-HPV types detected at 6 months (57%-93%) were persistent from baseline. Findings of anal cytologic tests were abnormal for 37% of women., Conclusions: Anal HPV is highly prevalent in women living with HIV, and type distribution varies by place of birth. High-resolution anoscopy was indicated in more than one third of results. As anal cancer is potentially preventable, these important findings need to be considered when selecting the best approach for anal cancer screening programs., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Recent birth cohorts vaccinated against human papillomavirus (HPV) may be protected against up to 4 genotypes (HPV-6, -11, -16, and -18). If natural competition exists between these and other HPV types, then the prevalence of other types may increase after vaccination., Methods: Cohort information from 3 studies was used to compare acquisition and clearance of 30 different HPV types (individually and grouped by species), according to infection status with vaccine-targeted types at baseline and the time of the index infection, respectively. Hazard ratios (HRs) were adjusted for predictors of multiple-type infection., Results: Among 3200 females across all studies, 857 were infected with HPV at baseline, and 994 acquired new infections during follow-up. Females infected with HPV-16 were at higher risk of acquiring other α-9 HPV types (HR, 1.9; 95% confidence interval [CI], 1.2-3.0) but at similar risk of clearing existing α-9 HPV infections (HR, 0.9; 95% CI, .7-1.3). Females infected with vaccine-targeted types were generally at higher risk of acquiring additional types (HRs, > 1.0) and at equal risk of clearing existing infections. Accounting for multiple comparisons, none of the HRs of < 1.0 or >1.0 were statistically significant in our analyses of acquisition or clearance., Conclusions: Vaccine-targeted HPV types do not appear to compete with other types, suggesting that HPV type replacement is unlikely to occur., (© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.)

Background: We studied features that predict the presence of human papillomavirus (HPV) in a new sexual partnership., Methods: We analyzed data from the "HPV Infection and Transmission Among Couples Through Heterosexual Activity" (HITCH) Cohort Study of recently formed partnerships ("dyads"). Women aged 18-24 and their male partners were recruited during 2005-2010 in Montreal, Canada. We tested genital swabs for detection of 36 HPV types. We defined HPV in a partnership as the presence of 1 or more HPV types in either or both partners. Using baseline data from 482 dyads, we calculated prevalence ratios to evaluate candidate risk factors., Results: Most women (88%) were unvaccinated. Sixty-seven percent of dyads harbored HPV. For 49% of dyads, both partners were HPV+. HPV was least prevalent in dyads who were in their first vaginal sex relationship (17%) and was virtually ubiquitous in dyads for which both partners had concurrent partners (96%). Dyads that always used condoms with previous partner(s) were 27% (95% confidence interval, 9%-42%) less likely to have HPV., Conclusions: The finding that condom use limited onward spread to future partners is in support of condom promotion to prevent sexually transmitted infections. Ongoing monitoring of HPV in sexual networks is needed, particularly in populations with suboptimal vaccine coverage., (© The Author 2014. 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.)

The Ontario HIV Treatment Network Cohort Study (OCS) is an observational, open dynamic cohort of people who are receiving medical care for human immunodeficiency virus (HIV) infection in Ontario, Canada. Established in the mid-1990s, the OCS has its roots in AIDS activists' demands for research that would improve the quality of life of people living with HIV while respecting their privacy. It is a collaborative and community-driven study, including a Governance Committee made up of people with HIV and other stakeholders that evaluates analysis project proposals for community relevance and ethics. From 1995 to 2010, a total of 5644 participants were enrolled and 27,720 person-years of observation were accumulated; follow-up will continue until at least 2015. In the initial years of study, the focus was on clinical data from medical chart reviews. It has since evolved into a comprehensive study that collects extensive de-identified information on clinical, laboratory and psychosocial and behavioural measures based on medical chart abstractions, interviews using a standardized questionnaire and linkage with external administrative health databases in Ontario. Interested collaborators are encouraged to submit analysis project proposals as instructed on the study website (www.ohtncohortstudy.ca).

Objectives: To characterize persons undergoing HIV genotypic resistance testing (GRT) while treatment naive and to estimate the prevalence of transmitted HIV drug resistance (TDR) among HIV-positive outpatients in Ontario, Canada., Methods: We analysed data from a multi-site cohort of persons receiving HIV care. Data were obtained from medical chart abstractions, interviews and record linkage with the Public Health Laboratories, Public Health Ontario. The analysis was restricted to 626 treatment-naive persons diagnosed in 2002-09. TDR mutations were identified using the calibrated population resistance tool. We used descriptive statistics and regression methods to characterize treatment-naive GRT test uptake and patterns of TDR., Results: Overall, 53.2% (333/626) of participants had baseline GRT. The proportion increased with year of HIV diagnosis from 30.0% in 2002 to 82.6% in 2009 (P < 0.0001). Among those tested, 13.6% (CI 9.9-17.3%) had one or more drug resistance mutations, and 8.8% (CI 5.7-11.8%), 4.8% (CI 2.5-7.2%) and 2.7% (CI 1.0-4.5%) had mutations conferring resistance to nucleoside/tide reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs), respectively. TDR prevalence increased from 2002-07 to 2008-09 (adjusted OR 3.7, 95% CI 1.7-8.2), driven by a higher proportion with NRTI (18.2% versus 5.9%, P = 0.0009) and NNRTI mutations (11.7% versus 2.8%, P = 0.004) in the later time period. PI TDR remained unchanged., Conclusions: Baseline GRT increased dramatically since 2002, but remains below 100%. The prevalence of overall TDR tripled due to increases in NRTI and NNRTI mutations. These findings highlight the value of routine baseline GRT for TDR surveillance and patient care.

We estimated human papillomavirus (HPV) transmission rates among persons with documented sexual exposure to an infected partner. Recently formed couples enrolled in the HITCH Study (HPV Infection and Transmission among Couples through Heterosexual activity) in Montreal, Canada, and provided genital specimens for DNA testing of 36 HPV genotypes. At enrollment, 179 couples were discordant for ≥1 HPV types; transmission was observed at follow-up in 73 partnerships. There was little difference between the male-to-female (3.5 per 100 person-months, 95% confidence interval [CI], 2.7-4.5) and female-to-male (4.0 per 100 person-months, 95% CI, 3.0-5.5) transmission rates. Rates did not vary with the lifetime number of partners reported by the initially uninfected partner, providing no evidence of reduced susceptibility for those with extensive sexual histories. Transmission was also relatively homogeneous across HPV genotypes and alpha species and oncogenic risk categories. The findings contribute to a small but growing evidence base regarding the natural history of HPV transmission.

The authors estimated plausible ranges of the probability of human papillomavirus (HPV) transmission per coital act among newly forming couples by using stochastic computer simulation. Comparative empirical data were obtained in 1996-2001 from a cohort study of female university students in Montreal, Canada. Female prevalence and frequency of sexual intercourse and condom use were set equal to those in the cohort. Simulations included 240 combinations of male prevalence, the relative risk for protected versus unprotected sex, and per-act transmission probabilities. Those that produced expected HPV incidence within the 95% confidence interval observed in the cohort were selected. The observed 6-month cumulative incidence following acquisition of a new partner was 17.0% (95% confidence interval: 11.4, 23.0). Expected incidences consistent with those from cohort findings occurred in 54/240 simulations. The range of per-act transmission probabilities was 5-100% (median, 40%). Male HPV prevalence was the same as or greater than that for women in all consistent simulations. Varying condom effectiveness did not produce better-fitting data. This simulation suggests that HPV transmissibility is several-fold higher than that for other viral sexually transmitted infections such as human immunodeficiency virus or herpes simplex virus 2. With high transmissibility, any potential protective effect of condoms would disappear over multiple intercourse acts, underlining the need for an effective HPV vaccine.

The objective of this analysis was to identify risk factors for recent human immunodeficiency virus (HIV) infection among homosexual and bisexual men in Ontario, Canada, during 1998-2001. Participants were recruited through the provincial HIV diagnostic laboratory and through physicians and community organizations. HIV test results were used to identify recent seroconverters (cases). A subsample of 183 men (62 cases and 121 controls) enrolled in the Polaris HIV Seroconversion Study as of June 2001 was analyzed. This analysis focused on sexual behaviors with partners who were HIV-positive or whose HIV status was unknown. In multiple logistic regression, independent risk factors were identified. Rates of unprotected receptive oral, insertive anal, and receptive anal sex and delayed application of condoms during receptive anal sex (RAS) were significantly higher among cases (97%, 41%, 53%, and 32%, respectively) than among controls (73%, 19%, 14%, and 2%). Independent risk factors for HIV infection were RAS without condoms (odds ratio = 4.4, p = 0.0004) and delayed application of condoms during RAS (odds ratio = 5.8, p = 0.01). There was an association with condom failure (breakage or slippage) during RAS that approached significance (odds ratio = 2.9, p = 0.09). Delayed application of condoms for RAS may result in contact with preejaculatory fluid. This behavior, which to date has received little attention, may pose as much risk for HIV infection as fully unprotected RAS.