The future role of rectal and vaginal microbicides to prevent HIV infection in heterosexual populations: implications for product development and prevention
- 1Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK
- 2Vaccine & Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- 3CAPRISA: Centre for the AIDS Program of Research in South Africa, University of KwaZulu-Natal, Durban, South Africa
- 4CHU Sainte-Justine Research Centre, University of Montreal, Montreal, Quebec, Canada
- Correspondence to Dr Marie-Claude Boily, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, Norfolk Place, Paddington, London W2 1PG, UK;
Contributors M-CB and DD designed the analysis. DD developed the model and performed the simulations. DD and M-CB analysed the results. M-CB drafted the first version of the manuscript. BM and SSAK provided input on different MB trial results. All authors helped with the parameterisation of the model, interpretation of the results and revised all drafts.
- Accepted 16 October 2011
Objectives 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.
Funding DD and BM are supported by a grant from the National Institutes of Health (Grant number 5 U01 AI068615-03).
Competing interests None.
Provenance and peer review Commissioned; externally peer reviewed.