Emerging evidence suggests that risk of bacterial sexually transmitted infections (STIs) increases among gay and bisexual men following initiation of HIV preexposure prophylaxis (PrEP). OBJECTIVE To describe STI incidence and behavioral risk factors among a cohort of predominantly gay and bisexual men who use PrEP, and to explore changes in STI incidence following PrEP commencement. DESIGN, SETTING, AND PARTICIPANTS The Pre-exposure Prophylaxis Expanded (PrEPX) Study, a multisite, open-label intervention study, was nested within the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance (ACCESS) clinic network. A total of 4275 participants were enrolled (July 26, 2016-April 1, 2018) in Victoria, Australia. Of these, 2981 enrolled at 5 ACCESS clinics (3 primary care, 1 sexual health, and 1 community-based HIV rapid testing service), had at least 1 follow-up visit, and were monitored until April 30, 2018. EXPOSURES Upon enrollment, participants received daily oral tenofovir disoproxil fumurate and emtricitabine for HIV PrEP, quarterly HIV and STI testing, and clinical monitoring. MAIN OUTCOMES AND MEASURES The primary outcome was incidence of chlamydia, gonorrhea, or syphilis. Incidence rates and hazard ratios describing behavioral risk factors of STI diagnosis were calculated. Incidence rate ratios (IRRs), adjusted for change in testing frequency, described changes in STI incidence from 1-year preenrollment to study follow-up among participants with preenrollment testing data (n = 1378). RESULTS Among the 2981 individuals (median age, 34 years [interquartile range, 28-42]), 98.5% identified as gay or bisexual males, 29% used PrEP prior to enrollment, 89 (3%) withdrew and were censored at date of withdrawal, leaving 2892 (97.0%) enrolled at final follow-up. During a mean follow-up of 1.1 years (3185.0 person-years), 2928 STIs were diagnosed among 1427 (48%) participants (1434 chlamydia, 1242 gonorrhea, 252 syphilis). STI incidence was 91.9 per 100 person-years, with 736 participants (25%) accounting for 2237 (76%) of all STIs. Among 2058 participants with complete data for multivariable analysis, younger age, greater partner number, and group sex were associated with greater STI risk, but condom use was not. Among 1378 participants with preenrollment testing data, STI incidence increased from 69.5 per 100 person-years prior to enrollment to 98.4 per 100 person-years during follow-up (IRR, 1.41 [95% CI, 1.29-1.56]). After adjusting for testing frequency, the increase in incidence from 1 year preenrollment to follow-up was significant for any STI (adjusted IRR, 1.12 [95% CI, 1.02-1.23]) and for chlamydia (adjusted IRR, 1.17 [95% CI, 1.04-1.33]). CONCLUSIONS AND RELEVANCE Among gay and bisexual men using PrEP, STIs were highly concentrated among a subset, and receipt of PrEP after study enrollment was associated with an increased incidence of STIs compared with preenrollment. These findings highlight the importance of frequent STI testing among gay and bisexual men using PrEP.

The aim of this analysis was to examine gay men's sexual risk practice to determine patterns of risk management. Ten cross-sectional surveys of gay men were conducted six-monthly from February 1996 to August 2000 at Sydney gay community social, sex-on-premises and sexual health sites (average n = 827). Every February during this period, five identical surveys were conducted at the annual Gay and Lesbian Mardi Gras Fair Day (average n = 1178). Among the minority of men who had unprotected anal intercourse which involved ejaculation inside with a serodiscordant regular partner, there was a clear pattern of sexual positioning. Few regular couples were both receptive and insertive. Most HIV-positive men were receptive and most HIV-negative men were insertive. Among the minority of men who had unprotected anal intercourse which involved ejaculation inside with casual partners, there was also a pattern of sexual positioning. Whereas many casual couples were both receptive and insertive (especially those involving HIV-positive respondents), among the remainder HIV-positive men tended to be receptive and HIV-negative men tended to be insertive. These patterns of HIV-positive/receptive and HIV-negative/insertive suggest strategic risk reduction positionings rather than mere sexual preferences among a minority of gay men. If so, they point not to complacency but to an ever more complex domain of HIV prevention.

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.