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Building on RV144: HIV Vaccine Trial Launches in South Africa

February 20, 2015
Early-stage trial aims to build on RV144 results

A clinical trial called HVTN 100 has been launched in South Africa to study an investigational HIV vaccine regimen for safety and the immune responses it generates in study participants. This experimental vaccine regimen is based on the one tested in the U.S. Military HIV Research Program-led RV144 clinical trial in Thailand—the first study to demonstrate that a vaccine can protect people from HIV infection. 

The experimental vaccine regimen tested in the RV144 trial was found to be 31.2 percent effective at preventing HIV infection 3.5 years after vaccination, although it appears to have been 60 percent effective one year after vaccination. 

In the HVTN 100 study, the design and schedule of the RV144 vaccine regimen have been altered to try to increase the magnitude and duration of vaccine-elicited immune responses. In addition, it has been adapted to the HIV subtype that predominates in southern Africa. MHRP has been conducting ongoing clinical studies (RV305 and RV306) in Thailand that have helped inform the design of this study, which include extra boosts.

The results of the HVTN 100 trial, expected in two years, will help determine whether or not this vaccine regimen will be tested for efficacy in a large future study in South Africa.

The HVTN 100 study is part of a larger HIV vaccine research endeavor led by a group called the Pox-Protein Public-Private Partnership, or the P5—a diverse set of public and private organizations, including MHRP, committed to building on the success of RV144. The P5 aims to produce an HIV vaccine that could have a significant public health benefit in southern Africa and to deepen scientists’ understanding of the immune responses associated with preventing HIV infection.

MHRP, in collaboration with the P5, is planning an efficacy trial in a high-risk population of men who have sex with men (MSM) in Thailand to hopefully improve upon the RV144 result and extend its relevance to at-risk populations to achieve the greatest public health impact.