Research Spotlight:
Professor David Dowdy

Picture of Professor David Dowdy

Meet David Dowdy

David Dowdy is a Professor and Executive Vice Dean for Academic Affairs at the Johns Hopkins Bloomberg School of Public Health. 

His research group, TB Modeling and Translational Epidemiology Group, focuses on the dynamic/mechanistic modeling of diseases like HIV and Tuberculosis (TB) to inform public health decision-making. 

Q: What is the focus of your research?

DD: “Our group studies primarily the epidemiology of HIV and Tuberculosis. We work in sub-Saharan Africa, Southeast Asia, Latin America, and across the globe. We try to figure out the factors that fuel the transmission of HIV and TB that make these two the leading infectious causes of death worldwide.”

Q. Your group is known for the dynamic modeling of TB and HIV. What is the process of developing these models?

DD: “We first start by determining the question we’re trying to answer, and then thinking through what we must model to answer such question. In some cases, this means modeling the transmission of these diseases in particular populations. Other times it means following a certain population over time to get a sense of what happens to them with no intervention versus other interventions that we might employ. 

Once we have come up with the overall structure, we translate it into computer code. We then must ensure that the code works and is representative of the structure and population we are trying to model. Finally, we analyze that model to see what the potential impact of those interventions might be.”

Q. How has computing impacted infectious disease epidemiology?

DD: “Many models like ours require a fair amount of computing power. In the past, having just enough power to run those simulations was a barrier. As computing power has become more accessible through resources like ARCH, it makes it easier to create better models. For example, certain models need millions of runs to figure out which runs are the best fit for the population. Two decades ago that would have never been possible, and even a decade ago it would have been very slow. Now we can make models in a way that is more statistically principled and provides reliable results.”

Q. One of your current projects focuses on using transmission models to aid in eliminating TB in the United States. Could you give us a brief overview of this project and how you use computational methods for your work?

DD: “One of the CDC’s priorities is the elimination of tuberculosis in the US. It’s important for us to get a sense of how best to use our existing resources to make the most progress that we can towards that goal. Our team has models, for example, looking at outbreak investigations. If there is an outbreak of TB, we want to be able to do a contact investigation to know how many resources are needed to deploy to a given outbreak and how much of an effect there is likely to be on containing that outbreak. We use different computational models to simulate what would happen in these outbreaks with and without different interventions, such as contact investigation or sequencing, to help prioritize the outbreak response. We are able to report this back to CDC, informing if these interventions are likely to have an effect and be cost-effective. That allows the CDC to justify resources to Congress and other funders.”

Q: What inspired you to pursue a research career in epidemiology?

DD: “I have always wanted to find ways to use quantitative data to improve the world in some way. There are many ways one can do that, but I landed in public health when I came to Johns Hopkins as a master’s student and enjoyed it. The field spoke to my brain about how we incorporate quantitative data, how such data might be biased or lead us to the wrong conclusions, and how we translate it to improve health.”

Q. What advice do you have for students who want to pursue a career in public health and epidemiology

DD: “It is important to find a topic that you are passionate about and to go forward with that. We all do better work and make more of an impact when we are doing something that we are excited about, and that we think is making a difference in our unique way. Think about what makes you passionate and find projects and people who will foster that passion. If you have that kind of excitement about what you’re doing and feel like you are doing your small part to make a difference, then many things will fall into place later on.”

Q. What is the impact or value of Rockfish on your research

DD: “Rockfish allows us to perform computational analysis that we otherwise would not be able to do. It allows us to construct these models, to calibrate them more effectively to data by making multiple runs and choosing the best out of those runs. There is much of our analysis that requires simulating such models millions of times. Therefore, having access not just to the resource of the computational power but also the support from a team that understands the mission is important for us.”

Q. What other resources would you like ARCH to provide?

DD: “Overall, we are very satisfied with ARCH’s resources and support.”