MELBOURNE, AUSTRALIA – Dr. Kenneth Mayer of the Fenway Institute and the Harvard School of Public Health offered a comprehensive look at HIV prevention technologies at the opening plenary today while emphasizing critical behavioral underpinnings associated with making those technologies effective. The significant prevention impact of treatment expansion, alone is not sufficient, Mayer said, with modelling data showing that even with full implementation of the 2013 World Health Organization treatment guidelines expanding treatment to an additional 10 million people, half a million people would still become infected with HIV each year.
But, he showed, prevention options have increased, and new ones in development are promising. Reminding his audience that adherence is the major predictor of effectiveness for pre-exposure prophylaxis, or PrEP, and that sexually transmitted infections and sexual violence also matter, Mayer outlined a number of studies that aim to optimize delivery of antiretrovirals for prevention and to make them easier to use, user-initiated, longer-acting, and multi-purpose.
The FACTS001 trial is testing the use of tenofovir gel used before and after sexual intercourse to prevent acquisition of both HIV and the herpes simplex virus in South Africa. With results expected next year, this could be the first approved topical gel PrEP product. Other studies are looking at other antiretroviral drugs in gels for vaginal and rectal use, and in microbicide rings with hopes that the rings could be effective for 3 months and might also be fitted with birth control compounds. The hope is that these rings will be easy to use, comfortable, not require insertion by a healthcare provider, and will be suitable for the developing world. Work also is underway on a contraceptive barrier, a silicone diaphragm for the over-the-counter distribution.
Long-acting injectable antiretroviral drugs are also in trials for prevention, as well as for treatment, and would potentially provide protection from HIV for a 3-month period, Mayer said. He also highlighted the potential of VRC01, a monoclonal antibody isolated from a person with HIV who is a long-term non-progressor. It will be evaluated as post-exposure prophylaxis in infants and adults, could potentially be developed into a topical film, and may inform development of an effective vaccine.
Mayer flagged two controversies associated with PrEP—the cost and who should provide it. He cited a Massachusetts study that found that HIV providers thought PrEP use should be managed by primary care providers since their focus was patients with established HIV infection while primary care providers said they didn’t have the expertise to manage antiretroviral use. The cost of PrEP also has sparked debate, and Mayer shared data demonstrating that PrEP becomes increasingly cost-effective when targeted to individuals and groups at high risk for HIV acquisition. Moreover, Mayer noted that many conditions have already called for treating large numbers of people to prevent a relatively small number of adverse health events, including statin drugs to reduce cardiovascular events associated with high cholesterol.
Mayer also highlighted medical circumcision as a high impact prevention technology, and noted that new devices and task-shifting hold promise for continued scale-up. People who inject drugs were identified by Mayer as a group with a clear need for harm reduction services in addition to other prevention interventions and he cited a study showing that the combination of antiretroviral therapy and buprenorphine in HIV primary care settings led to more viral suppression.
Mayer reminded his audience that prevention technologies operate in a web of social issues at the individual, community and policy level, requiring attention to resources and human rights. He pointed to a website, www.hivresourcetracking.org, that provides information that includes expenditures by intervention.
Finally, Mayer honored the memory of his colleague Joep Lange, who he said “as a treatment expert recognized very early on the potential prevention benefit of antiretroviral drugs.”