Biomedical Approaches to HIV Prevention

1. Biomedical Approaches to HIV Prevention HIV Research Catalyst Forum April 21, 2010, Baltimore, MD Monica S. Ruiz, PhD, MPH George Washington University School of Public Health and Health Services

2. HIV Prevention Strategies Behavioral Risk Reduction VCT PEP Behavioral Risk Reduction VCT Treatment of Addiction Treatment of Addiction NEP/SEP Infected Person (transmission & disease progression) NEP/SEP Susceptible Person (acquisition) ART Male Circumcision Treatment of STD and OI STD Treatment PMTCT PMTCT Microbicide Microbicide Vaccine Vaccine PrEP

3. Biomedical & Technological Interventions • Decrease susceptibility to HIV by: • Reducing risk of exposure to the virus • If exposed, reduce risk of the virus “taking hold” • Decrease infectiousness of HIV by: • Reducing viral load • Reducing the other biological factors (e.g., infections) that increase transmission risk

4. Condoms • Male, latex condoms are 80% to 95% effective in reducing the risk of HIV transmission when used consistently and correctly • Female condoms are estimated to be between 94% and 97% effective in reducing risk of STI, including HIV, transmission when used consistently and correctly References: NIH, 2001; Hearst & Chen 2003; Weller & Davis 2004; Holmes, et al. 2004; Trussell et al. 1994.

5. Preventing Mother-to-Child Transmission • Long- and short-course AZT and single-dose NVP are effective in reducing MTCT by 44% to 66% • Breast-milk substitutes have been shown to significantly reduce infection among infants. • The number of children who acquired HIV perinatally decreased by 89% between 1992 and 2001 Sources: Brocklehurst 2004; Cooper et al. 2002.

6. Male Circumcision • Two meta-analyses of observational studies found the risk of acquiring HIV among circumcised men was about half that of uncircumcised men. • Data from three RCTs showed that circumcision has a significant protective effect against HIV acquisition • South Africa: 61% protective • Kenya: 53% protective • Uganda: 48% protective Sources: Weiss, et al. 2000; Siegfried, et al. 2004; Auvert, et al. 2005; Bailey et al., 2007; Gray et al., 2007

8. Cervical Barrier Methods • The cervix may be particularly vulnerable to HIV and STI transmission. • The MIRA trial found that there was no added protective benefit from the diaphragm. • But the trial was not designed to determine whether the use of the cervical barrier was better than nothing at all. • Other cervical barriers, when combined with an effective microbicide, may be more successful in preventing HIV infection Sources: Padian et al., 2007

9. Microbicides Viral disruption/inactivation Prevention of other STDs HIV physical barrier lubrication Lactobacillus Vaginal epithelium Maintenance of normal microflora

10. Microbicide Trial results to date

11. Vaccines

12. X X

15. Treatment and Management of Sexually Transmitted Infections • STIs increase susceptibility to HIV infection. • Having HSV-2 infection (genital herpes) is associated with 3x higher risk of HIV acquisition. • HSV-2 can also increase infectiousness of HIV+. • STI management may be most effective in populations with concentrated sexually transmitted HIV epidemics and in populations with high prevalence of STIs and sexual risk behaviors Sources: Freeman et al. 2006; Grosskurth et al. 1995; Wawer, et al 1999; Kamali, et al 2003; Korenromp et al. 2005.

16. HSV-2 Trial Results • Two trials of HSV-2 treatment in HIV-uninfected persons showed no protective effect against HIV acquisition • One trial of HSV-2 treatment among HIV+ persons showed no evidence of reducing rates of HIV transmission • Mixed results re: the impact of HSV-2 treatment on genital HIV shedding, viral load levels, genital HSV shedding, etc.

17. Post-Exposure Prophylaxis (PEP) • A short course of ART taken within 72 hours of exposure can be effective in preventing HIV infection • One study of occupational PEP found that AZT taken within 24 hrs. of exposure and over 28 days reduced HIV acquisition by 81% Sources: Cardo et al. 1997; Wulfsohn 2003; Mayer 2003.

18. Pre-Exposure Prophylaxis (PrEP)

19. Many difficult questions are associated with PrEP

20. Ongoing PrEP Trials Source: www.avac.org

22. So what do we know? • Biomedical strategies are only one piece of the prevention puzzle • Behavioral, social, and structural interventions are important too! • It is not likely that any one intervention will be 100% effective. • We must not confuse lack of implementation with lack of effectiveness.

23. Other important factors that must be considered in HIV prevention • Psychological, social, economic, and cultural dynamics of gender and sexuality • New and changing context for both sexual and substance use behavior • Differences in the perceived consequences of HIV infection • Social, structural, environmental factors and contexts that contribute to the HIV/AIDS epidemic

24. Access to & Delivery of Prevention Services Stigma & Discrimination/ Social Support -- scaling up effective programs -- policies -- financing prevention services -- customs -- norms -- institutions Social Equity/Inequality Social Stability/Instability -- war -- race/ethnicity -- sex/gender -- violence -- age -- migration -- immigration/citizenship -- famine -- class/income/wealth PEP/PREP Behavioral Risk Reduction VCT Behavioral Risk Reduction VCT RxAddiction Rx Addiction NEP/SEP Infected Person (transmission & disease progression) Susceptible Person (acquisition) ART NEP/SEP Rx HIV Rx STD Rx OI Rx STD Perinatal Perinatal Microbicide Microbicide Vaccine Vaccine

26. Thank you for your attention!