Sexual behavior is heterogeneous and dynamic. Characterization of such complexity constitutes evidence for public health authorities and caregivers concerned with the framing of sexual health messages aimed at specific subgroups. We developed a machine-learning-based methodology for inference and characterization of such subgroups from longitudinal data on men who have sex with men (MSM) attending individual sexual health counseling sessions. Because longitudinal data take time to record, we assessed the ability of first visit data to predict subgroups' membership. Our methodology comprised two main steps: (1) Hierarchical clustering to group 2349 HIV-negative MSM based on their self-reported longitudinal sexual behavior during visits to Swiss sexual health counseling centers between November 2016 and April 2019; and (2) Random forest-based classification to predict subgroup membership from first visit data. We found six subgroups with significant differences in behavioral trends, most of which sharply deviated from the overall trends. Two subgroups, which contained 37% of the study population, accounted for over 70% of the overall increases in condomless anal intercourse with non-steady partners, group sex, and having more than five anal intercourse partners. Subgroup-specific trends in online-dating and group sex were heterogeneous with opposing trends across subgroups. Data from first visits predicted trends of sexual behavior with accuracy ranging from 64 to 86%. This study evidenced specific sexual behavioral subgroups that might benefit from customized sexual health messages, demonstrated that first visit registries could predict subgroups, and contributes an algorithmic alternative for establishing subgroups relevant to inform customized sexual health messages that capture sexual behavioral diversity.

BACKGROUND: Changes in mental and sexual health among men having sex with men (MSM) due to the SARS-CoV-2 pandemic remain unclear. METHODS: Design: Longitudinal analysis of an ongoing, multicentre, pre-exposure prophylaxis (PrEP) cohort (NCT03893188) in Switzerland. Participants: HIV-negative MSM aged ≥18 who completed at least one questionnaire before and one after the start of the SARS-CoV-2 pandemic. Outcomes: Primary: mental health, defined as anxiety and depression scores assessed by the Patient Health Questionnaire-4. Secondary: sexual behaviour, well-being, PrEP use and disruption of care. Outcomes were assessed over seven periods corresponding to different SARS-CoV-2 prevention measures in Switzerland. We performed pairwise comparisons between periods (Wilcoxon signed rank test). RESULTS: Data from 1,043 participants were included. Whilst anxiety scores remained stable over time, depression scores worsened in the second wave and the second lockdown period compared to pre-pandemic scores. This was confirmed by pairwise comparisons (pre-SARS-CoV-2/second wave and pre-SARS-CoV-2/second lockdown: p <0.001). Downward trends in sexual activity,sexualized substance use, and a switch from daily to "event-driven" PrEP were found. Disruption of care affected 42.6% (790/1856) of daily PrEP users’ follow-up visits. CONCLUSION: In this longitudinal analysis of a PrEP cohort enrolling MSM, depression scores worsened in the second wave and the second lockdown compared to the pre-pandemic period.

Alors que plus de 400 personnes sont encore infectées par le virus de l'immunodéficience humaine (VIH) en Suisse chaque année, il est question d'une fin de l'épidémie de VIH parmi les spécialistes locaux ainsi que dans les plans stratégiques de la Commission fédérale pour les questions liées aux infections sexuellement transmissibles (CFIT) et de l'Office fédéral de la santé publique (OFSP).Nous tentons de donner un aperçu de la proximité de la fin de l'épidémie de VIH en Suisse, du rôle que joue la prophylaxie pré-exposition (PrEP) au VIH pour atteindre cet objectif, et de ce qu'est «SwissPrEPared».

Die HIV-Diagnostik hat in den letzten zwei Jahren verschiedene Neuerungen erfahren. Was muss man 2021 über verkürzte Testintervalle, Selbsttests und die HIV-PCR wissen? Welche Bedeutung haben sie für die praktische Arbeit?

Le diagnostic du VIH a connu différentes nouveautés au cours des deux dernières années. Que faut-il savoir en 2021 sur les délais de test raccourcis, les autotests et la PCR VIH? Quelles sont leurs implications pour la pratique?

Objectives To study the implementation, effects and costs of Break the Chains, a community-based HIV prevention campaign for men who have sex with men (MSM) in Switzerland, from March to May 2015, which aimed to reduce early HIV transmission by promoting the campaign message to adopt short-term risk reduction followed by HIV testing. Design Non-randomised evaluation and cost analysis. Setting Gay venues in 11 of 26 cantons in Switzerland and national online media campaign. Participants MSM in online surveys (precampaign n=834, postcampaign n=688) or attending HIV testing centres (n=885); campaign managers (n=9); and campaign staff (n=38) or further intermediaries (n=80) in an online survey. Primary and secondary outcome measures The primary outcome measure was the proportion of MSM at risk of HIV acquisition or transmission who adhered to the campaign message. Secondary outcomes were postcampaign test uptake, knowledge about HIV primary infection and sense of belonging to the gay community. Results Campaign staff estimated that they contacted 17 145 MSM in 11 cantons. Among 688 respondents to the postcampaign survey, 311 (45.2%) were categorised as MSM at risk. Of 402/688 (58.5%) MSM who had heard about Break the Chains 2015, MSM categorised as being at risk were less likely to report adherence to the campaign message than MSM not at risk (adjusted OR 0.24; 95% CI 0.14 to 0.42). Twenty per cent of MSM with a defined risk of HIV acquisition or transmission who adopted risk reduction declared having done so because of the campaign. Costs for one MSM at risk to adhere to the campaign message were estimated at USD purchasing power parity 36–55. The number of HIV tests in the month after the campaign was twice the monthly average. Conclusion Break the Chains increased HIV testing, implying that community-based campaigns are useful HIV prevention strategies for MSM. Additional interventions are needed to reach MSM at the highest risk of infection more effectively.

Background Hepatitis C virus reinfections in HIV-positive men-who-have-sex-with-men (MSM) challenge the effectiveness of antiviral treatment. To fight this problem, an adapted sexual risk reduction intervention was implemented within a hepatitis C treatment trial. Following this, the current study had two aims and describes 1) how the program was received by participants; and 2) their responses to the program regarding sexual risk taking. Based on the participants’ input, we hoped to judge the intervention’s potential for scale-up. Methods Seventeen participants who received the sexual risk reduction intervention in addition to hepatitis C treatment were recruited for semi-structured interviews six to 12 months post-intervention. We evaluated the responses via reflexive thematic analysis and applied the concept of sense-making. Results Giving hepatitis C a place and living without it again illustrates how participants received the program and how their experiences were altered by the impact of sense-making. Based on their responses, we allocated participants to three groups: 1. Avoid risks: get rid of hepatitis C for life . For these men, hepatitis C remained a life-threatening disease: they actively modified their risk behavior and felt supported by the intervention in maintaining their behavioral changes. 2. Minimize risks: live as long as possible without hepatitis C. In contrast to group 1, these men saw hepatitis C as a manageable disease. The intervention facilitated reflection on risks and how to develop behavioral changes that suited them individually. 3. Accept risks; live with the risk of hepatitis C. These men perceived behavioral changes as much more difficult than “easy” medical treatment. They expected to either undergo repeated rounds of treatment or stay HCV re-infected. Conclusion These results illustrate the diversity of men’s responses and their decisions regarding sexual risk behavior after participating in a combination of antiviral treatment and a sexual risk reduction intervention. Two major aspects were identified: 1) Teachable moments, particularly at the time of diagnosis/treatment, could offer an opportunity to develop openness for behavioral change; 2) adapting sexual risk reduction interventions to sense-making patterns could help to improve its effectiveness. Support for reducing infection risk and raising awareness of preventative measures are additional benefits. Trial registration Clinical Trial Number: NCT02785666 , 30.05.2016.