Reductions in HIV transmission risk behaviour following diagnosis of primary HIV infection: A cohort of high-risk men who have sex with men

Background: Risk-reduction counselling is a standard preventive intervention, but behaviour change is difficult to sustain over the duration of HIV infection. However, primary HIV infection (PHI) is highly infectious and plays a key role in transmission - especially through dense sexual networks - but is short term, so even transient risk reduction can mitigate its high infectivity. Targeting behaviour-change interventions at recently infected individuals may be highly effective, particularly in higher risk groups. We explored the potential impact on HIV transmission-risk behaviour of PHI diagnosis in men who have sex with men (MSM). Methods: MSM with PHI were interviewed at diagnosis and after 3 months of follow-up about their sexual behaviour in the 12-week periods before and after diagnosis and standard counselling. Results: A total of 98 of 104 eligible MSM (94%) participated in the study, with 100% follow-up. PHI was associated with high levels of recreational drug use, low levels of condom use, high numbers of sexual partners and a history of sex work. In the 12 weeks post-diagnosis, 76% of participants eliminated risk of onward transmission entirely and, overall, there was a significant reduction in transmission-risk behaviour, with patients reporting greater condom use and fewer sexual partners. Those with continued transmission-risk behaviour were more likely to have another sexually transmitted infection (STI), use ketamine and have more sexual partners at baseline. Conclusions: Most MSM recently diagnosed with PHI changed their behaviour to substantially reduce the risk of onward HIV transmission. Strategies are needed to (a) increase diagnoses of PHI to target prevention efforts effectively and (b) further reduce risk behaviours by targeting enhanced counselling to those most likely to continue with risk behaviours.