Q&A with Victor DeGruttola

Victor DeGruttola

trtransmissionMartha Henry, Editor of Spotlight, asked Dr. DeGruttola about the Botswana Combination Prevention Project.

Dr. Victor DeGruttola, Chair of the Dept. of Biostatistics at the Harvard School of Public Health, is the Co-Principal Investigator of the Botswana Combination Prevention Project (BCPP). The BCPP is a large clinical trial that combines available HIV prevention methods to try to control HIV at a community level.

What does it mean to control HIV at a ‘community level’?

Within an individual, we know the processes by which cells get infected, virus replicates, and antiretrovirals (ARVs) interfere with that process. We need similar kinds of models at the community level that describe transmission across individuals. The goal is to learn at the community level what we’ve learned over the decades about individual therapy: how to optimize treatments and tailor them to individual characteristics. We need to know what the community-level factors are that affect the impact of prevention interventions in order to use the results of BCPP in designing prevention strategies for Africa.

How is the BCPP different from previous clinical trials to prevent HIV infections?

Individual-level trials have produced a lot of very important information, but don’t tell us all we need to know. They provide useful information about reduction of an individual’s risk of HIV infection (or transmission), but the trials don’t tell us how to control the HIV epidemic at a community level. It’s like if you’re fighting a war, you need to know how individual weapons work and what they’re useful for, but to win, you have to know how to put them all together.

What will we learn from the BCPP?

By the end of this study, we should be able to say whether combination prevention methods, including treating all highly viremic patients, can bring about a major reduction in HIV infection in villages in Botswana. We’ll also learn what level of coverage of interventions is needed at the community level to achieve targets for HIV incidence reduction.

We know that at the individual level HIV treatment works well. But we also know that if patients don’t take their ARV medications as directed, it can do them more harm than good. We need to understand what kind of community-level compliance with an intervention program is needed for the program to succeed, and how this level depends on the HIV dynamics within the community.

What is the definition of success for the BCPP?

The study is designed to have an impact of reducing HIV incidence [new infections] by 50% in the intervention communities compared to the control communities.

But what’s most important is that the epidemic be made unsustainable in the communities where the intervention is offered. In other words, the community by itself could not sustain an epidemic. New cases will arise from contacts outside the community. But if the epidemic were not sustainable within a community, and if all surrounding communities got the intervention as well, then we should be able to control the epidemic in ever-larger geographic units, and ultimately in entire countries that receive interventions. This must be the primary goal of HIV prevention research.