Boily, Marie-Claude.Dimitrov, Dobromir.Abdool Karim, Salim Safurdeen.Masse, Benoit.2012-11-202012-11-2020112011Boily, M-C. et al. 2011. The future role of rectal and vaginal microbicides to prevent HIV infection in heterosexual populations: implications for product development and prevention. Sex Transm Infect. 87 (7) pp. 646–653.1368-4973http://dx.doi.org/10.1136/sextrans-2011-050184http://hdl.handle.net/10413/7907Objectives. To compare the potential impact of rectal (RMB), vaginal (VMB) and bi-compartment (RVMB) (applied vaginally and protective during vaginal and anal intercourse) microbicides to prevent HIV in various heterosexual populations. To understand when a RMB is as useful than a VMB for women practicing anal intercourse (AI). Methods. Mathematical model was used to assess the population-level impact (cumulative fraction of new HIV infections prevented (CFP)) of the three different microbicides in various intervention scenarios and prevalence settings. We derived the break-even RMB efficacy required to reduce a female’s cumulative risk of HIV infection by the same amount than a VMB. Results. Under optimistic coverage (fast roll-out, 100% uptake), a 50% efficacious VMB used in 75% of sex acts in population without AI may prevent -33% (27, 42%) new total (men and women combined) HIV infections over 25 years. The 25-year CFP reduces to -25% (20, 32%) and 17% (13, 23%) if uptake decreases to 75% and 50%, respectively. Similar loss of impact (by 25% - 50%) is observed if the same VMB is introduced in populations with 5% - 10% AI and for RRRAI=4-20. A RMB is as useful as a VMB (ie, break-even) in populations with 5% AI if RRRAI=20 and in populations with 15% - 20% AI if RRRAI=4, independently of adherence as long as it is the same with both products. The 10-year CFP with a RVMB is twofold larger than for a VMB or RMB when AI=10% and RRRAI=10. Conclusions. Even low AI frequency can compromise the impact of VMB interventions. RMB and RVMB will be important prevention tools for heterosexual populations.enHIV infections--Prevention and control.Rectal microbicides.Vaginal microbicides.Peer reviewed journal article