Treatment as Prevention
Investment in Research & Development Related to Treatment as Prevention
Investment in research into the early initiation of AIDS treatment drugs as a prevention strategy reached US$92 million in 2014 (Figure 25). Four years after the release of trial data from HPTN 052, showing that people living with HIV who started ART at CD4 cell counts between 350 and 500 were significantly less likely to transmit HIV to their sexual partners, compared with people who started according to national guidelines, ongoing research seeks to answer questions about how best to implement treatment as prevention programmatically, and to address implementation in specific populations and settings.
Results released in 2014 showed the benefits of earlier initiation of treatment, modeling studies estimated the cost-effectiveness of earlier treatment initiation and implementation research addressed how to bring to scale treatment for prevention. Advances in 2014 include:
- Data from the Strategic Timing of AntiRetroviral Treatment (START) study released in May 2015 showed that HIV-infected individuals have a lower risk of developing AIDS if they start treatment earlier, when their CD4 count is higher, instead of waiting for CD4 levels to drop to lower levels. Along with data from previous studies showing that treatment reduced the risk of HIV transmission to uninfected sexual partners, the START findings support offering treatment to everyone with HIV and are further evidence supporting the expansion of ART access.
- Observational data from the PARTNER study showed no transmission events in serodiscordant couples in which the HIV-positive partner had a viral load of less than 200 copies/mL. The study includes both heterosexual participants and gay men and other men who have sex with men.
- A review and meta-analysis of studies of HIV transmission in serodiscordant heterosexual couples showed a very low transmission rate per unprotected sex act when the HIV-positive partner was on treatment for at least six months prior.
- The coming years will provide additional insights into the durability of treatment as prevention. In July 2015, the HPTN 052 trial is set to release results and will provide longer-term data on treatment as prevention among heterosexual couples. The START trial is expected to complete in the next few years, providing further evidence of the clinical benefits of early treatment initiation.