Preparing for Mpox Resurgence: Surveillance Lessons From Outbreaks in Toronto, Canada.

BACKGROUND: With many global jurisdictions, Toronto, Canada, experienced an mpox outbreak in spring/summer 2022. Cases declined following implementation of a large vaccination campaign. A surge in early 2023 led to speculation that asymptomatic and/or undetected local transmission was occurring in the city. METHODS: Mpox cases and positive laboratory results are reported to Toronto Public Health. Epidemic curves and descriptive risk factor summaries for the 2022 and 2023 outbreaks were generated. First- and second-dose vaccination was monitored. Mpox virus wastewater surveillance and whole genome sequencing were conducted to generate hypotheses about the source of the 2023 resurgence. RESULTS: An overall 515 cases were reported in spring/summer 2022 and 17 in the 2022-2023 resurgence. Wastewater data correlated with the timing of cases. Whole genome sequencing showed that 2022-2023 cases were distinct from 2022 cases and closer to sequences from another country, suggesting a new importation as a source. At the start of the resurgence, approximately 16% of first-dose vaccine recipients had completed their second dose. CONCLUSIONS: This investigation demonstrates the importance of ongoing surveillance and preparedness for mpox outbreaks. Undetected local transmission was not a likely source of the 2022-2023 resurgence. Ongoing preexposure vaccine promotion remains important to mitigate disease burden.

Can laboratory HIV and infectious syphilis data inform future pre-exposure prophylaxis use in women in Ontario, Canada?

OBJECTIVES: Infectious syphilis has been proposed as an indication for HIV pre-exposure prophylaxis (PrEP) in women. We explored how many women experienced HIV seroconversion after being diagnosed with syphilis in Ontario between 20 April 2010 and 31 December 2021. METHODS: Through deterministic linkage of laboratory data at the Public Health Ontario laboratory, which conducts the vast majority of syphilis and HIV testing in Ontario, we quantified the number of females with positive syphilis diagnoses who subsequently exhibited HIV seroconversion between April 2010 and December 2021. New HIV cases were identified by diagnostic serology or HIV viral load test result of ≥20 copies/mL at least 60 days after the positive syphilis test. We report aggregate numbers of women with new laboratory evidence of HIV infection after their first positive syphilis test. RESULTS: Among 7957 women with positive syphilis tests during the study period, 6554 (82.4%) had linkable HIV serology tests and 133 (1.7%) ever tested HIV positive. With further linkage to viral load data, the number of women who ever had laboratory evidence of HIV infection increased to 184 (2.3%). However, when restricting to women whose first positive HIV test or HIV viral load occurred after their first positive syphilis test, this number decreased to 34 (0.4%). The median (IQR) time between the positive syphilis test and the first laboratory evidence of HIV was 551 (IQR=226-1159) days. CONCLUSION: Although it is clinically appropriate to recommend HIV PrEP to women with syphilis, Ontario surveillance data suggest that the population-level impact of this strategy on the HIV epidemic in Ontario would have been modest during this 11-year period. Future studies should explore additional ways of prioritising women for PrEP.

HIV pre-exposure prophylaxis and opportunities for vaccination against hepatitis A virus, hepatitis B virus and human papillomavirus: an analysis of the Ontario PrEP cohort study.

OBJECTIVES: Populations who seek HIV pre-exposure prophylaxis (PrEP) are disproportionately affected by hepatitis A virus (HAV), hepatitis B virus (HBV) and human papillomavirus (HPV). We examined immunity/vaccination against these infections among participants in the Ontario PrEP cohort study (ON-PrEP). METHODS: ON-PrEP is a prospective cohort of HIV-negative PrEP users from 10 Ontario clinics. We descriptively analysed baseline immunity/vaccination against HAV (IgG reactive), HBV (hepatitis B surface antibody >10) and HPV (self-reported three-dose vaccination). We further performed multivariable logistic regression to identify characteristics associated with baseline immunity/vaccination. We used cumulative incidence functions to describe vaccine uptake among participants non-immune at baseline. RESULTS: Of 633 eligible participants, 59.1% were white, 85.8% were male and 79.6% were gay. We found baseline evidence of immunity/vaccination against HAV, HBV and HPV in 69.2%, 81.2% and 16.8% of PrEP-experienced participants and 58.9%, 70.3% and 10.4% of PrEP-naïve participants, respectively. Characteristics associated with baseline HAV immunity were greater PrEP duration (adjusted OR (aOR) 1.41/year, 95% CI 1.09 to 1.84), frequent sexually transmitted and bloodborne infection (STBBI) testing (aOR 2.38, 95% CI 1.15 to 4.92) and HBV immunity (aOR 3.53, 95% CI 2.09 to 5.98). Characteristics associated with baseline HBV immunity were living in Toronto (aOR 3.54, 95% CI 1.87 to 6.70) or Ottawa (aOR 2.76, 95% CI 1.41 to 5.40), self-identifying as racialised (aOR 2.23, 95% CI 1.19 to 4.18), greater PrEP duration (aOR 1.39/year, 95% CI 1.02 to 1.90) and HAV immunity (aOR 3.75, 95% CI 2.19 to 6.41). Characteristics associated with baseline HPV vaccination were being aged ≤26 years (aOR 9.28, 95% CI 2.11 to 40.77), annual income between CAD$60 000 and CAD$119 000 (aOR 3.42, 95% CI 1.40 to 8.34), frequent STBBI testing (aOR 7.00, 95% CI 1.38 to 35.46) and HAV immunity (aOR 6.96, 95% CI 2.00 to 24.25). Among those non-immune at baseline, overall cumulative probability of immunity/vaccination was 0.70, 0.60 and 0.53 among PrEP-experienced participants and 0.93, 0.80 and 0.70 among PrEP-naïve participants for HAV, HBV and HPV, respectively. CONCLUSIONS: Baseline immunity to HAV/HBV was common, and a sizeable proportion of non-immune participants were vaccinated during follow-up. However, HPV vaccination was uncommon. Continued efforts should be made to remove barriers to HPV vaccination such as cost, inclusion in clinical guidelines and provider recommendation.

Human Immunodeficiency Virus Treatment Attitudes and Bacterial Sexually Transmitted Infections Among Gay and Bisexual Men.

BACKGROUNDS: Positive attitudes toward human immunodeficiency virus (HIV) treatment, such as reduced concern about HIV transmissibility, are associated with sexual behaviors that may increase the risk of bacterial sexually transmitted infections (STIs) among gay, bisexual, and other men who have sex with men (GBM). We examined associations between HIV treatment attitudes and bacterial STI diagnoses among GBM in Canada's three largest cities. METHODS: We fit a structural equation model between HIV treatment attitudes and bacterial STI diagnoses via sexual behaviors in the Engage study's baseline data. We estimated direct and indirect paths between scores on HIV treatment attitudes and STIs via number of male anal sex partners, condomless anal sex, and oral sex. We conducted sub-analyses with participants stratified by HIV serostatus. RESULTS: Among 2449 GBM recruited in 2017 to 2019, there was a direct association between HIV treatment attitudes and current STI diagnoses (ß = 0.13; 95% CI, 0.07-0.19; P < 0.001). The mediated model revealed a positive total indirect effect through 2 pathways: (1) engaging in condomless anal sex and (2) number of male anal sex partners and condomless anal sex. These 2 indirect pathways remained in the stratified mediation models for both HIV negative GBM and for GBM living with HIV. CONCLUSIONS: The association between HIV treatment attitudes and diagnosed STIs is mediated through a higher number of male anal sex partners and condomless anal sex. The results highlight the importance of providers educating patients when providing effective STI counseling, testing, and prevention for GBM about how accurate HIV treatment attitudes may inadvertently be associated with the bacterial STI epidemic.

End of selection criteria based on sexual orientation: An international symposium on alternatives to donation deferral.

BACKGROUND AND OBJECTIVES: Until recently, gay, bisexual and other men who have sex with men (MSM) were deferred from donating blood for 3-12 months since the last male-to-male sexual contact. This MSM deferral has been discontinued by several high-income countries (HIC) that now perform gender-neutral donor selection. MATERIALS AND METHODS: An international symposium (held on 20-04-2023) gathered experts from seven HICs to (1) discuss how this paradigm shift might affect the mitigation strategies for transfusion-transmitted infections and (2) address the challenges related to gender-neutral donor selection. RESULTS: Most countries employed a similar approach for implementing a gender-neutral donor selection policy: key stakeholders were consulted; the transition was bridged by time-limited deferrals; donor compliance was monitored; and questions or remarks on anal sex and the number and/or type of sexual partners were often added. Many countries have now adopted a gender-neutral approach in which questions on pre- and post-exposure prophylaxis for human immunodeficiency virus (HIV) have been added (or retained, when already in place). Other countries used mitigation strategies, such as plasma quarantine or pathogen reduction technologies for plasma and/or platelets. CONCLUSION: The experience with gender-neutral donor selection has been largely positive among the countries covered herein and seems to be acceptable to stakeholders, donors and staff. The post-implementation surveillance data collected so far appear reassuring with regards to safety, although longer observation periods are necessary. The putative risks associated with HIV antiretrovirals should be further investigated.

'It's not as good as the face-to-face contact': A sociomaterialist analysis of the use of virtual care among Canadian gay, bisexual and queer men during the COVID-19 pandemic.

The COVID-19 pandemic led to the widespread adoption of virtual care-the use of communication technologies to receive health care at home. We explored the differential impacts of the rapid transition to virtual care during the COVID-19 pandemic on health-care access and delivery for gay, bisexual and queer men (GBQM), a population that disproportionately experiences sexual and mental health disparities in Canada. Adopting a sociomaterial theoretical perspective, we analysed 93 semi-structured interviews with GBQM (n = 93) in Montreal, Toronto and Vancouver, Canada, conducted between November 2020 and February 2021 (n = 42) and June-October 2021 (n = 51). We focused on explicating how the dynamic relations of humans and non-humans in everyday virtual care practices have opened or foreclosed different care capacities for GBQM. Our analysis revealed that the rapid expansion and implementation of virtual care during the COVID-19 pandemic enacted disruptions and challenges while providing benefits to health-care access among some GBQM. Further, virtual care required participants to change their sociomaterial practices to receive health care effectively, including learning new ways of communicating with providers. Our sociomaterial analysis provides a framework that helps identify what works and what needs to be improved when delivering virtual care to meet the health needs of GBQM and other diverse populations.

Vaccine Effectiveness Against 12-Month Incident and Persistent Anal Human Papillomavirus Infection Among Gay, Bisexual, and Other Men Who Have Sex With Men.

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.

Treatment-emergent reverse transcriptase resistance during antiretroviral therapy with bictegravir, tenofovir alafenamide, and emtricitabine: A case series.

OBJECTIVES: Bictegravir/tenofovir alafenamide/emtricitabine (BIC/TAF/FTC) is a complete regimen for the treatment of HIV with a high barrier to resistance and few reported cases of treatment failure. We present three cases of treatment-emergent resistance to nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) in patients with suboptimal treatment adherence and assess whether the resistance-associated mutations were present before BIC/TAF/FTC initiation or emerged during therapy. METHODS: We used genotypic drug resistance testing by Sanger sequencing to identify emergent resistance mutations in plasma viral load specimens collected after combination antiretroviral therapy initiation in all participants. Additionally, we performed ultra-deep sequencing by Illumina MiSeq on the earliest available plasma HIV-1 viral load specimen and on any available specimens closest in time to the initiation of BIC/TAF/FTC therapy to identify low-abundance resistance mutations present in the viral quasispecies. RESULTS: All three participants developed NRTI resistance after prolonged exposure and incomplete adherence to BIC/TAF/FTC. The T69N, K70E, M184I, and/or T215I mutations identified in clinical samples at the time of virological failure were not present on deep sequencing of either baseline samples or samples collected before BIC/TAF/FTC initiation. CONCLUSIONS: Despite a generally high genetic barrier to resistance, NRTI resistance-associated mutations may emerge during therapy with BIC/TAF/FTC in the setting of suboptimal adherence.

Self-reported Human Papillomavirus Vaccination and Vaccine Effectiveness Among Men Who Have Sex with Men: A Quantitative Bias Analysis.

BACKGROUND: Self-report of human papillomavirus (HPV) vaccination has ~80-90% sensitivity and ~75-85% specificity. We measured the effect of nondifferential exposure misclassification associated with self-reported vaccination on vaccine effectiveness (VE) estimates. METHODS: Between 2017-2019, we recruited sexually active gay, bisexual, and other men who have sex with men aged 16-30 years in Canada. VE was derived as 1-prevalence ratio × 100% for prevalent anal HPV infection comparing vaccinated (≥1 dose) to unvaccinated men using a multivariable modified Poisson regression. We conducted a multidimensional and probabilistic quantitative bias analysis to correct VE estimates. RESULTS: Bias-corrected VE estimates were relatively stable across sensitivity values but differed from the uncorrected estimate at lower values of specificity. The median adjusted VE was 27% (2.5-97.5th simulation interval = -5-49%) in the uncorrected analysis, increasing to 39% (2.5-97.5th simulation interval = 2-65%) in the bias-corrected analysis. CONCLUSION: A large proportion of participants erroneously reporting HPV vaccination would be required to meaningfully change VE estimates.

Disclosure of HIV-serodiscordant relationships and association with viral suppression: results from the Positive Plus One study.

BACKGROUND: Little is known about the effects of disclosure of HIV-serodiscordant relationships on clinical outcomes. We aimed to evaluate the effect of relationship disclosure on HIV viral suppression, and hypothesized that disclosure by HIV-positive and HIV-negative partners would be associated with viral suppression in the HIV-positive partner. METHODS: We conducted a Canadian national online and telephone-administered survey of HIV-positive and HIV-negative partners in serodiscordant relationships. The primary outcome was self-reported viral suppression. Multivariable analyses were undertaken using Firth logistic regression. RESULTS: We recruited 540 participants in current serodiscordant relationships (n = 228 HIV-negative; n = 312 HIV-positive). Similar proportions of HIV-positive and HIV-negative partners disclosed their relationship to healthcare professionals (82% v. 76%, p = 0.13). Among HIV-positive partners, disclosure of the relationship to healthcare professionals increased the odds of viral suppression (aOR = 4.7; CI: 2.13, 10.51) after adjusting for age, education, and relationship turmoil due to HIV. Increasing age (aOR = 1.28; 95% CI = 1.07, 1.55) and education (aOR = 2.43; 95% CI = 1.15, 5.26) were also associated with viral suppression. Among HIV-negative partners, relationship disclosure was not associated with viral suppression and HIV-negative heterosexual men were less likely to report that their HIV-positive partners were virally suppressed (aOR = 0.24; CI: 0.09, 0.61). CONCLUSIONS: Disclosure of HIV-serodiscordant status by HIV-positive participants to healthcare professionals was associated with increased odds of viral suppression. Similar effects were not evident among HIV-negative participants. Future work should explore factors that empower relationship disclosure and incorporate them into supportive services for HIV-serodiscordant relationships.

Disjuncture between self-perceived and clinically assessed risk of HIV among gay, bisexual, and other men who have sex with men in Ontario and British Columbia, Canada.

BACKGROUND: Self-perceived and clinically assessed HIV risk do not always align. We compared self-perceived and clinically assessed risk of HIV and the reasons for self-perceived low risk of HIV among gay, bisexual, and other men who have sex with men (GBM) from large urban centers in Ontario and British Columbia, Canada. METHODS: Never PrEP users recruited from sexual health clinics or online, completed a cross-sectional survey between July/2019 and August/2020. We contrasted self-perceived HIV risk against criteria from the Canadian PrEP guidelines and participants were categorized as concordant or discordant. We used content analysis to categorize participants' free-text explanations for perceived low HIV risk. These were compared with answers to quantitative responses about condomless sex acts and number of partners. RESULTS: Of 315 GBM who self-perceived low risk of HIV, 146 (46%) were considered at high risk according to the guidelines. Participants with discordant assessment were younger, had less years of formal education, were more often in an open relationship and were more likely to self-identify as gay. Reasons for self-perceived low HIV risk in the discordant group were condom use (27%), being in a committed relationship/having one main partner (15%), having no or infrequent anal sex (12%) and having few partners (10%). CONCLUSIONS: There is a disjuncture between self-perceived and clinically assessed risk of HIV. Some GBM may underestimate their HIV risk and clinical criteria may overestimate risk. Bridging these gaps requires efforts to increase HIV risk awareness in the community, and refinement of clinical assessments based on individualized discussions between the provider and the user.

'I did not have sex outside of our bubble': changes in sexual practices and risk reduction strategies among sexual minority men in Canada during the COVID-19 pandemic.

In efforts to prevent the spread of COVID-19, jurisdictions across the globe, including Canada, enacted containment measures that affected intimacy and sexual relations. This article examines how public health measures during COVID-19 impacted the sexual practices of sexual minority men- gay, bisexual, queer and other men who have sex with men-and how they adopted and modified guidelines to prevent the transmission of COVID-19, HIV and other sexually transmitted infections (STIs). We conducted 93 semi-structured interviews with men (n = 93) in Montreal, Toronto and Vancouver, Canada, between November 2020 to February 2021 (n = 42) and June to October 2021 (n = 51). Across jurisdictions, participants reported changes to sexual practices in response to public health measures and shifting pandemic contexts. Many men indicated that they applied their HIV/STI risk mitigation experiences and adapted COVID-19 prevention strategies to continue engaging in casual sexual behaviours and ensure sexual safety. 'Social bubbles' were changed to 'sex bubbles'. Masks were turned into 'safer' sex tools. 'Outdoor gathering' and 'physical distancing' were transformed into 'outdoor sex' and 'voyeuristic masturbation'. These strategies are examined in connection to the notion of 'reflexive mediation' to illustrate how sexual minority men are simultaneously self-responsibilising and resistant, self-monitoring and creative.

Gay, bisexual, and queer men's confidence in the Undetectable equals Untransmittable HIV prevention message: longitudinal qualitative analysis of the sexual decision-making of pre-exposure prophylaxis users over time.

BACKGROUND: Our objective was to understand what gay, bisexual, and queer men (GBQM) who had experience using pre-exposure prophylaxis (PrEP) thought about the 'Undetectable equals Untransmittable' (U=U) message and how it informed their sexual decision-making over time. METHODS: We conducted annual longitudinal qualitative interviews (2020-22) with 17 current or former PrEP users as part of a mixed-methods implementation science study examining barriers and facilitators to PrEP awareness, access, and adherence. Over 3years, 47 interviews were conducted with GBQM in Ontario, Canada. Interviews were transcribed verbatim and coded in NVivo following reflexive thematic analysis. RESULTS: Participants' sexual health decision-making was informed by their confidence in biomedical HIV prevention and the person taking medication (i.e. themselves using PrEP versus a real/imagined person living with HIV (PLHIV)). Longitudinal narratives of U=U clustered around four overarching themes: (1) U=U confidence (i.e. increasing trust in U=U irrespective of their PrEP use); (2) PrEP confidence (i.e. accounts of self-reliance and PrEP as sufficient HIV protection); (3) combination confidence (i.e. trusting U=U and PrEP as a package); and (4) partner confidence (i.e. potential 'distrust' of U=U due to uncertainties about partners' medication adherence). Overall, men described increased sex with PLHIV over time, including some participants who, during earlier interviews, said they would 'never be comfortable' with serodifferent sexual partners. CONCLUSIONS: GBQM's use of PrEP shaped how they thought about U=U and sex with PLHIV. Although many GBQM embraced treatment as prevention/U=U as significant to their sexual lives, longitudinal analysis revealed its varied and uneven adoption across participants and time.

HIV pre-exposure prophylaxis: It is time to consider harm reduction care for adolescents in Canada.

Youth (aged 15 to 29 years) account for one quarter of new HIV cases in Canada. Of those, men-who-have-sex-with-men make up one third to one half of new cases in that age range. Moreover, Indigenous youth are over-represented in the proportion of new cases. The use of emtricitabine/tenofovir disoproxil fumarate as pre-exposure prophylaxis (PrEP) significantly reduces the risk of HIV acquisition in adults. Its use was expanded to include youth over 35 kg by the U.S. Food and Drug Administration in 2018. However, PrEP uptake remains low among adolescents. Prescriber-identified barriers include lack of experience, concerns about safety, unfamiliarity with follow-up guidelines, and costs. This article provides an overview of PrEP for youth in Canada, and its associated safety and side effect profiles. Hypothetical case vignettes highlight some of the many demographics of youth who could benefit from PrEP. We present a novel flow diagram that explains the baseline workup, prescribing guidelines, and follow-up recommendations in the Canadian context. Additional counselling points highlight some of the key discussions that should be elicited when prescribing PrEP.

Routinized Syphilis Screening Among Men Living With Human Immunodeficiency Virus: A Stepped Wedge Cluster Randomized Controlled Trial.

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.

Maximizing the impact of limited vaccine supply under different early epidemic conditions: a 2-city modelling analysis of monkeypox virus transmission among men who have sex with men.

BACKGROUND: The current global monkeypox virus (MPXV) outbreak has disproportionately affected gay, bisexual and other men who have sex with men (GBMSM). Given that many jurisdictions have been faced with limited supplies of MPXV vaccine, we aimed to explore optimal vaccine allocation between 2 linked GBMSM transmission networks over a short-term time horizon, across several epidemic conditions. METHODS: We constructed a deterministic compartmental MPXV transmission model. We parameterized the model to reflect 2 representative, partially connected GBMSM sexual networks ( cities), using 2022 data from Ontario. We simulated a roll-out of 5000 vaccine doses over 30 days that started 45 days after epidemic seeding with 10 imported cases. Within this model, we varied the relative city (network) sizes, epidemic potentials (R 0), between-city mixing and distribution of seed cases between cities. For each combination of varied factors, we identified the allocation of doses between cities that maximized infections averted by day 90. RESULTS: Under our modelling assumptions, we found that a limited MPXV vaccine supply could generally avert more early infections when prioritized to networks that were larger, had more initial infections or had greater R 0. Greater between-city mixing decreased the influence of initial seed cases and increased the influence of city R 0 on optimal allocation. Under mixed conditions (e.g., fewer seed cases but greater R 0), optimal allocation required doses shared between cities. INTERPRETATION: In the context of the current global MPXV outbreak, we showed that prioritization of a limited supply of vaccines based on network-level factors can help maximize infections averted during an emerging epidemic. Such prioritization should be grounded in an understanding of context-specific risk drivers and should acknowledge potential connectedness of multiple transmission networks.

PrEP-related stigma and PrEP use among gay, bisexual and other men who have sex with men in Ontario and British Columbia, Canada.

BACKGROUND: We aimed to explore the association between PrEP-related stereotypes and perceived disapproval (hereafter PrEP-related stigma), and PrEP use. METHODS: We used data from a cross-sectional online survey among adult gay, bisexual, other men who have sex with men in Ontario and British Columbia, Canada. Participants were recruited 2019-2020 in-person from sexual health clinics and outreach programs, and online through dating mobile applications and websites. We used logistic regression models to explore the relationship between PrEP-related stigma and: 1-being a 'never' versus 'current' PrEP user, and 2-being a 'former' versus 'current' user. RESULTS: The median age of the sample was 32 (Q1-Q3 = 27-40), most were white born in Canada (48%), 45% had never used PrEP, 16% were former PrEP users and 39% were current PrEP users. Of 1527 individuals who started the survey, 1190 participants answered questions about PrEP-related stigma: 254 (21.3%) were classified as having low level of PrEP-related stigma, 776 (65.2%) intermediate, and 160 (13.5%) high. No significant association was found when never PrEP users and current PrEP users were compared: adjusted OR = 1.44 (95%-CI: 0.8-2.5). High PrEP-related stigma was positively associated with being a former PrEP user compared to being a current PrEP user: adjusted OR = 2.5 (95%-CI: 1.3-4.9). CONCLUSION: PrEP-related stigma is associated with not using PrEP, particularly with PrEP discontinuation. Our findings indicate that stigma persists as a barrier to PrEP use.

A national recruitment strategy for HIV-serodiscordant partners living in Canada for the Positive Plus One study: a mixed-methods study.

BACKGROUND: With the recent shift in focus to addressing HIV risk within relationships and couple-based interventions to prevent HIV transmission, successful recruitment of individuals involved in HIV-serodiscordant relationships is crucial. This paper evaluates methods used by the Positive Plus One (PP1) study to recruit and collect data on a diverse national sample of dyads and individuals involved in current or past HIV-serodiscordant relationships, discusses the strengths and limitations of the recruitment approach, and makes recommendations to inform the interpretation of study results and the design of future studies. METHODS: PP1 used a multi-pronged approach to recruit adults involved in a current or past HIV-serodiscordant relationship in Canada from 2016 to 2018 to complete a survey and an interview. Upon survey completion, index (first recruited) partners were invited to recruit their primary current HIV-serodiscordant partner. We investigated participant enrollment by recruitment source, participant-, relationship-, and dyad-level sociodemographic characteristics, missing data, and correlates of participation for individuals recruited by their partners. RESULTS: We recruited 613 participants (355 HIV-positive; 258 HIV-negative) across 10 Canadian provinces, including 153 complete dyads and 307 individuals who participated alone, and representing 460 HIV-serodiscordant relationships. Among those in current relationships, HIV-positive participants were more likely than HIV-negative participants to learn of the study through an ASO staff member (36% v. 20%, p < 0.001), ASO listserv/newsletter (12% v. 5%, p = 0.007), or physician/staff at a clinic (20% v. 11%, p = 0.006). HIV-negative participants involved in current relationships were more likely than HIV-positive participants to learn of the study through their partner (46% v. 8%, p < 0.001). Seventy-eight percent of index participants invited their primary HIV-serodiscordant partner to participate, and 40% were successful. Successful recruitment of primary partners was associated with longer relationship duration, higher relationship satisfaction, and a virally suppressed HIV-positive partner. CONCLUSIONS: Our findings provide important new information on and support the use of a multi-pronged approach to recruit HIV-positive and HIV-negative individuals involved in HIV-serodiscordant relationships in Canada. More creative strategies are needed to help index partners recruit their partner in relationships with lower satisfaction and shorter duration and further minimize the risk of "happy couple" bias.

"What other choices might I have made?": Sexual Minority Men, the PrEP Cascade and the Shifting Subjective Dimensions of HIV Risk.

The PrEP Cascade is a dominant framework for investigating barriers to HIV pre-exposure prophylaxis (PrEP), an HIV prevention tool. We interviewed 37 PrEP users and 8 non-PrEP users in Ontario and British Columbia, Canada, about their decision-making through the Cascade. Participants were HIV-negative gay, bisexual, and queer men (GBQM). The data were analyzed using thematic analysis. PrEP decision-making was based on pragmatic considerations (logistics, costs, and systemic barriers), biomedical considerations (efficacy, side-effects, and sexually transmitted infections), and subjective considerations (identity, politics, and changing sexual preferences). Affective attachments to established versions of "safer sex" (condoms and serosorting) made some GBQM less likely to try PrEP. Some GBQM expressed increased social expectations to use PrEP, have condomless sex, and serodifferent sex. These findings support offering PrEP at no-cost, offering individualized counseling and community-based opportunities to discuss PrEP use and changing sexual practices, and improving communication on the manageability of PrEP side-effects.

Interest in Hypothetical Preexposure Prophylaxis Against Herpes Simplex Virus: A Cross-Sectional Survey.

ABSTRACT: We surveyed 383 men who have sex with men attending sexual health clinics regarding interest in hypothetical preexposure prophylaxis against herpes simplex virus. Overall interest was 62.5% and was associated with the number of different sexually transmitted infections previously diagnosed (adjusted odds ratio, 1.9; 95% confidence interval, 1.5-2.6) and previous HIV preexposure prophylaxis use (adjusted odds ratio, 2.9; 95% confidence interval, 1.1-8.3).