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Objective-A range of risk reduction behaviours in which homosexual men practise unprotected anal intercourse (UAI) has been described. We aimed to assess the extent of any reduction in HIV risk associated with these behaviours.Design-A prospective cohort study of HIV-negative homosexual men in Sydney, Australia. Methods-Men were followed up with 6-monthly detailed behavioural interviews and annual testing for HIV. The four risk reduction behaviours (behaviourally defined) examined were serosorting, negotiated safety, strategic positioning, and withdrawal during receptive UAI (UAI-R).Results-In 88% of follow-up periods in which UAI was reported, it occurred in the context of consistent risk reduction behaviours. Compared with those who reported no UAI, the risk of HIV infection was not raised in negotiated safety [hazard ratio = 1.67, 95% confidence interval (CI) 0.59-4.76] and strategic positioning (hazard ratio = 1.54, 95% CI 0.45-5.26). Serosorting outside negotiated safety was associated with an intermediate rate of HIV infection (hazard ratio = 3.11, 95% CI 1.09-8.88). Withdrawal was associated with a higher risk than no UAI (hazard ratio = 5.00, 95% CI 1.94-12.92). Patterns of UAI differed greatly according to partner's serostatus. Men who reported serosorting were less likely to report either strategic positioning or withdrawal.Conclusion-Each behaviour examined was associated with an intermediate HIV incidence between the lowest and highest risk sexual behaviours. The inverse association between individual behaviours suggests that men who practise serosorting rely on this protection. The high prevalence of these behaviours demands that researchers address the contexts and risks associated with specific types of UAI.

Objective-To estimate per-contact probability of HIV transmission in homosexual men due to unprotected anal intercourse (UAI) in the era of highly active antiretroviral therapy (HAART).Design-Data were collected from a longitudinal cohort study of community-based HIV-negative homosexual men in Sydney, Australia.Methods-A total 1427 participants were recruited from June 2001 to December 2004. They were followed up with 6-monthly detailed behavioral interviews and annual testing for HIV till June 2007. Data were used in a bootstrapping method, coupled with a statistical analysis that optimized a likelihood function for estimating the per-exposure risks of HIV transmission due to various forms of UAI.Results-During the study, 53 HIV seroconversion cases were identified. The estimated per-contact probability of HIV transmission for receptive UAI was 1.43% (95% CI 0.48%-2.85%) if ejaculation occurred inside the rectum occurred, and it was 0.65% (95% CI 0.15%-1.53%) if withdrawal prior to ejaculation was involved. The estimated transmission rate for insertive UAI in participants who were circumcised was 0.11% (95% CI 0.02%-0.24%), and it was 0.62% (95% CI 0.07%-1.68%) in uncircumcised men. Thus, receptive UAI with ejaculation was found to be approximately twice as risky as receptive UAI with withdrawal or insertive UAI for uncircumcised men and over 10-times as risky as insertive UAI for circumcised men.Conclusion-Despite the fact that a high proportion of HIV-infected men are on antiretroviral treatment and have undetectable viral load, the per-contact probability of HIV transmission due to UAI is similar to estimates reported from developed country settings in the pre-HAART era. KeywordsHIV; per-contact probability; transmission risk; cohort study; homosexuality, male; Australia

Background: Early detection and treatment of bacterial sexually transmitted infections has been advocated as an HIV prevention strategy. Aim: To inform screening guidelines, the incidence and risk factors for urethral and anal gonorrhoea and chlamydia were studied in a prospective cohort of community-based HIV negative homosexual men in Sydney, New South Wales, Australia. Methods: All participants were offered annual screening for gonorrhoea and chlamydia (study-visit diagnoses) on urine and anal swabs using nucleic acid amplification. Participants also reported diagnoses of gonorrhoea and chlamydia made elsewhere between interviews (interval diagnoses). All diagnoses were summed to create a combined incidence rate, and detailed data on specific sexual practices with casual and regular partners were collected. Results: Among 1427 men enrolled, the combined incidence rates were 3.49 and 2.96 per 100 person-years for urethral and anal gonorrhoea, respectively; and 7.43 and 4.98 per 100 person-years for urethral and anal chlamydia, respectively. Urethral infections were associated with unprotected anal intercourse (UAI) with HIV-positive partners (hazard ratio (HR) = 2.58, 95% CI 1.10 to 6.05 for urethral gonorrhoea) and with frequent insertive oral sex (p for trend 0.007 for urethral chlamydia). Anal infections were associated with receptive UAI (p for trend 0.001 for both anal gonorrhoea and chlamydia) and other receptive anal sexual practices. Stratified analyses showed the independence of the associations of insertive oral sex with urethral infections and of non-intercourse receptive anal practices with anal infections. Conclusion: Incident gonorrhoea and chlamydia were common. Risk behaviours for both urethral and anal infections were not restricted to UAI. Screening that includes tests for anal and urethral infections should be considered for all sexually active homosexual men, not just for those who report UAI.

Introduction: In March 2020, Australian state and federal governments introduced physical distancing measures alongside widespread testing to combat COVID-19. These measures may decrease people's sexual contacts and thus reduce the transmission of HIV and other sexually transmissible infections (STIs). We investigated the impact of physical distancing measures due to COVID-19 on the sexual behavior of gay and bisexual men in Australia. Methods: Between April 4, 2020, and April 29, 2020, 940 participants in an ongoing cohort study responded to questions to measure changes in sexual behaviors during the COVID-19 pandemic. Men reported the date they become concerned about COVID-19 and whether they engaged in sexual behavior with regular or casual partners or “fuckbuddies” in the 6 months before becoming concerned about COVID-19 (hereafter referred to as “before COVID-19”), and following the date, they become concerned about COVID-19 (hereafter referred to as “since COVID-19”). Before and since COVID-19 was based on individual participants' own perceived date of becoming concerned about COVID-19. Results: The mean age of was 39.9 years (SD: 13.4). Most participants (88.3%) reported sex with other men during the 6 months before COVID-19. Of the 587 men (62.4%) who reported sex with casual partners before COVID-19, 93 (15.8%) continued to do so in the period since COVID-19, representing a relative reduction of 84.2%. Conclusion: Gay and bisexual men in Australia have dramatically reduced their sexual contacts with other men since COVID-19. These behavioral changes will likely result in short-term reductions in new HIV and STI diagnoses. If sexual health screenings are undertaken before resuming sexual activity, this could present a novel opportunity to interrupt chains of HIV and STI transmission.

We explored seroguessing (serosorting based on the assumption of HIV seroconcordance) and casual unprotected anal intercourse (UAIC) associated with seroguessing. The ongoing Positive Health and Health in Men cohorts, Australia, provided data for trends in seroconcordant UAIC and HIV disclosure to sex partners. In event-level analyses, we used log-binomial regression adjusted for within-individual correlation and estimated prevalence rate ratios (PRRs) and 95% confidence intervals (95% CIs) for the association between the knowledge of a casual partner's seroconcordance and UAIC. UAIC and HIV disclosure significantly increased during 2001-2006. HIV-positive men knew partners were seroconcordant in 54% and assumed it in 13% of sex encounters (42 and 17% among HIV-negative men). Among HIV-positive men, the likelihood of UAIC was higher when a partner's status was known (Adjusted PRR = 5.17, 95% CI: 3.82-7.01) and assumed seroconcordant because of seroguessing (Adjusted PRR = 3.70, 95% CI: 2.56-5.35) compared with unknown. Among HIV-negative men, the likelihood of UAIC was also higher when a partner's status was known (Adjusted PRR = 1.88, 95% CI: 1.58-2.24) and assumed seroconcordant (Adjusted PRR = 2.12, 95% CI: 1.72-2.62) compared with unknown. As levels of UAIC remain high, seroguessing increasingly exposes gay men to the risk of HIV infection. Because both HIV-positive and HIV-negative men often seroguess, education and prevention programs should address the fact that HIV-negative men who engage in UAI due to this practice may be at high risk of HIV infection. HIV prevention should take into account these contemporary changes in behaviors, especially among HIV-negative gay men.