1. How well are we doing in preventing HIV and how can we do better?
Peter Piot
Institute for Global Health
Global HIV/AIDS vaccine enterprise

2. PREVENTION WORKS BUT...

3. Community mobilisation, Thailand’s 100% Condom Program
Pilot in Ratchaburi province
Implementation on a national scale
Structural approaches that have sought to reduce the HIV vulnerability of sex workers have ranged from policies to enforce condom use to programmes that sought to build solidarity among and empower sex workers. Assessment of the 100% condom use policy in Thailand revealed that condom use climbed to over 90% (figure 3).40 Similar outcomes were reported from a more recent study of the effect of a 100% condom use policy combined with efforts to build community solidarity among sex workers in Puerto Plata in the Dominican Republic (panel 4).41
Figure 3 Full-size image (42K)
Increase in condom use reported by sex workers in sentinel serosurveillance
Reproduced with permission form UNAIDS.40
Proportion of condom use with Reported STD nationally
recent clients
Source: UNAIDS Case Study: Evaluation of the 100% Condom Programme in Thailand, 2000.

4. HIV Prevalence Declines in Pregnant Women
As this slide shows, there have also been declines in HIV prevalence in pregnant women in recent years. There are a number of effective HIV prevention methods available today, including safer sex, safer injection practices, condom use, and male circumcision. There are, however, also social obstacles attached to each of these. And we have seen that, even when these interventions are fully funded and supported by states and social institutions, they have only been able to drive HIV infection rates down to a certain level. In order to further reduce HIV incidence we need new biomedical tools -- the most important of these will be an effective HIV vaccine.
Source: National surveillance reports and UNAIDS/WHO/UNICEF, Epidemiological Fact Sheets on HIV and AIDS.  July 2008.

5. Behavioural change, impact in urban and semi-urban Zimbabwe
M1: assuming behavioural change, better fit to surveillance data
Natural decline in incidence ~1990
Accelerated decline in incidence, due to behaviour change ~2000
M0: without behavioural change
Fitted models for Zimbabwe data in urban and semi-urban areas.
The posterior modal simulation is plotted for model M0 (without behaviour change: dashed blue line); and for model M1 (with behaviour change: solid black line). The prevalence data are also shown as grey crosses and lines.
HIV incidence (per 100 person years at risk) for the entire posterior sample of simulations is plotted. Each thin grey line is one simulation, the thick red line is the mode, and the dashed black lines show the 2.5th and 97.5th percentiles of the distribution of prevalence.
Source: Hallett TB, et al. Epidemics 2009;1(2):

6. R0 = β c D Basic reproductive rate Transmission probability
Mean duration of infection
Condom use
ART
Microbicides
PrEP
PMTCT
Circumcision
Clean needles
VCT
ART
Mean number of contacts
VCT
Behavioural change
Substitution therapy

7. Effectiveness of condoms in preventing STIs including HIV
This review of prospective studies published identified evidence that consistent condom use is associated with reduced transmission in HIV
Source: Holmes KK, et al. Bull World Health Organ. 2004;82(6):

8. Source: UNAIDS, UNICEF & WHO, 2008; data provided by countries.
Number and percentage of HIV-positive pregnant women receiving antiretroviral prophylaxis
2004
2006
2005
Number of HIV-positive pregnant women receiving anti-retrovirals
Year
% of HIV-positive pregnant women
receiving anti-retrovirals 5 30 35 15 20 25 40 10
2007
Only 35% of HIV positive pregnant women receiving ART
Source: UNAIDS, UNICEF & WHO, 2008; data provided by countries.

9. Reduction of acquisition risk after male circumcision
(A) South Africa
(B) Kenya
(C) Uganda
>50% reduction in risk of acquisition for men
Infection-Free Probability
Cumulative sero-incidence
Cumulative probabilities of HIV detection
Source: (A) Auvert B, et al. PLoS Med 2005;2(11): e298, (B) Bailey RC, et al. Lancet 2007; 369:643–656 and (C)Gray RH, et al. Lancet 2007; 369:657–666.

10. RCT: Treatment of STIs
Source: Ronald Gray, Plenary lecture - Biomedical HIV Prevention Trials (A Sisyphean Task). Cape Town, IAS conference July 2009.

11. Decriminalisation

13. Concurrency
Strong case in modelling for concurrency as a determinant of HIV in southern Africa
BUT
Empirical evidence is lacking
Polygyny protective
More research needed on sexual networks
Standard definitions needed for concurrency
What is the intervention?

14. Population impact of treatment as prevention
Time trends resulting from application of universal voluntary HIV testing and immediate ART strategy for people who test HIV positive, in combination with other adult prevention interventions that reduce incidence by 40%
Source: Granich RM, et al. Lancet 2009; 373: 48–57.

15. NO MAGIC BULLET

16. Combination prevention
Source: Coates TJ, et al. Lancet 2008; 372:669–84.

17. Source: Hallett TB, et al. PLoS ONE 2008;3(5): e2212
Interaction of circumcision interventions with existing behaviour change programmes
Four epidemic projections show: (i) no interventions, (ii) circumcision intervention with 90% coverage, (iii) a behaviour change intervention that leads to an average 30% reduction in partner change rate and 30% increase in condom use with casual partners, (iv) both the circumcision intervention and the behaviour change intervention. The output is HIV incidence per 100 person-years at risk (pyar). The time-scale relates to years since the circumcision intervention starts. (Note: Unlike in other simulations, here no compensation is made for the potential effects of AIDS mortality modifying the risk distribution in the population
Projected effect of different prevention interventions on HIV incidence
Source: Hallett TB, et al. PLoS ONE 2008;3(5): e2212

18. Effectiveness /efficacy and controversies
Rates of HIV infection during typical and perfect use
Source: Cates W. Technical advances in HIV prevention, in HIV/AIDS Annual Update In: Phair JP, ed. Clinical Care Options, 2006.

19. Know your epidemic Cambodia, 1988-2004
5000
10000
15000
20000
25000
30000
35000
40000
45000
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Male clients
Sex workers
Wife from husband
Husband from wife
Mother to child
Number of new HIV infections by route of transmission
Source: Peerapatanapokin and Brown, using Asia Epidemic Model

20. Know your epidemic Lithuania
2004
2008
Proportion of HIV diagnosed cases by transmission category
Source: Strujeva O , et al. Poster CDC079 – HIV infection trends in Lithuania in 2004 – Cape Town, IAS conference July 2009.

21. Source: www.avac.org/timeline-website/
HIV Prevention Research Time-line of Expected Efficacy Trial Results (AVAC)
2007
2008
2009
2010
2011
2012+
STEP (HVTN 502/ Merck 023)
HSV-2 SUPPRESSION (HPTN 039)
HPTN 035
CDC 4323
iPrEx
CDC 4940
PHAMBILI
Male Circumcision in HIV+ Men
PARTNERS IN PREVENTION
CDC 4370
PARTNERS PrEP
MIRA
CARRAGUARD
ALVAC-AIDSVAX
CAPRISA 004
FEM-PrEP
MDP 301
HVTN 505
VOICE (MTN-003)
HPTN 052
Source:

22. AIDS IS NOT OVER

23. The prevention gap
To have an impact with already efficient prevention methods, we need more coverage
Percentage of population groups most at risk with access to prevention services, 2008
Source: WHO/UNICEF/UNAIDS. Towards Universal Access. Scaling up priority HIV/AIDS interventions in the health sector. Progress report 2009.

25. Treatment Action Campaign (TAC), South Africa

26. Source: SIDALAC/UNAIDS. 2001
Preventive expenditure for men who have sex with men and % of AIDS cases among them
Source: SIDALAC/UNAIDS. 2001

27. Cost Effectiveness

28. The long term view
Stop generic response to heterogeneous problem
Start structural interventions NOW
Invest in professionals and institutions
Donor indicators and incentives focus on long term impact
Maximise programme efficiency
R&D

29. Combination treatment + Combination prevention + Vaccine???