3 Essential Questions with Luke Davis, MD, MAS

Luke Davis, MD, MAS, associate professor of epidemiology at the Yale School of Public Health (YSPH), who also practices as a pulmonary and critical care physician at Yale School of Medicine, has spent his career at the intersection of two of the leading infectious causes of death worldwide: tuberculosis (TB) and HIV.

As director of YSPH's Implementation Science MPH Concentration, Davis leads international research training programs in implementation science — an emerging interdisciplinary field focused on closing the gap between what works in research and what actually gets delivered in clinics and communities. The goal: public health programs that are more effective, efficient, and equitable.

Scientifically, we've never been in a better place than we are now, and that’s the result of long-term investments in clinical and basic research. We now have the knowledge and tools to diagnose, treat, and prevent these infections and achieve excellent individual outcomes. TB and HIV deaths and new diagnoses are down by more than 50% over the last two decades, a remarkable achievement.

We now have a promising new TB vaccine, which is in Phase III trials at sites around the globe. And we have long-acting preventable agents for HIV that are nearly 100% effective against new infections. With recent progress, we are close to having the tools we need to control both of these infections as public health threats.

In contrast to the scientific advances, progress in the care and control of TB and HIV has stalled in the wake of the global COVID-19 pandemic and retrenchment by the United States as the leading global funder of recent gains. We still have more than a million new HIV infections every year, and more than 10 million new TB diagnoses — causing an enormous amount of suffering to people in the prime of their lives.

Implementation science is an area of public health focused on getting proven interventions into everyday policy and practice to maximize health outcomes for populations.

Early in my career, a new molecular test for TB was hailed as a significant advancement. People thought it would identify the millions of people who get TB every year but never get diagnosed. Unfortunately, when the testing machines were introduced, they weren’t fully used, and people testing positive weren't getting results on time. So, in collaboration with the Uganda National TB Program, academic researchers, and outside partners, our group, Walimu, conducted research to understand why implementation of this test wasn't impactful, and importantly, to develop strategies to change that.

During Version 2.0 of the test rollout, staff were positioned at the clinic gates, and lay health workers were sent into the community to find people who needed testing. Test results were sent via text message. We developed measurement systems and dashboards to help public health practitioners find and address delivery gaps. The number of people successfully diagnosed and treated doubled.

We subsequently found that this strategic and supportive approach to implementation can be adapted to other TB and HIV innovations. We have even used this approach in selected settings in the United States to make TB care and testing more efficient, enhance patient and provider experiences, and substantially reduce costs.

I draw confidence from the fact that the investments of the last two decades have not only advanced TB and HIV science but have also created a community of global partners. This includes people living with TB and HIV, frontline clinicians and policymakers, and the researchers who've advanced discovery by listening to the advice and critiques of this community. In the short term, these partnerships will continue to pay dividends as they share data and learnings from past collaborations.

What worries me is that we don’t yet have a clear model for sustaining this progress. I believe that we must expand beyond external funders and meaningfully engage local governments, businesses, social entrepreneurs, and nonprofits in high-burden countries to tackle TB, HIV, and other diseases of poverty. And we must train the next generation of investigators and public health leaders to advance this work. I feel confident that when we show people how much society gains from long-term academic-public health partnerships, they will commit themselves to sustaining progress in TB and HIV care globally.