Who Is This Ren Fellow?

Someone asked me the other day to explain my trajectory to where I am now. Five hours later, and we were not even close to finishing. To some, I am a friend. To others, I am a shill for Big Pharma who pushed vaccines for a living. To a certain little girl, I am her dad. To my wife, I’m her better half (and the source of many an eye-roll).

I am an epidemiologist with a doctoral degree in epidemiology, a master’s degree in public health (epidemiology and biostatistics) and a bachelor’s in medical technology. While I’ve always loved science, I also dabble in technology and other disciplines.

I was born and raised in Mexico and moved to the United States when I was ten. When I received my bachelor’s in medical technology, a small hospital in Pennsylvania recruited me to work in their clinical laboratory. That was quite the adventure. I got to see all sorts of interesting medical cases, interact with all sorts of healthcare professionals, and begin building the foundation for all that I know today about public health. With the encouragement of friends and colleagues at the hospital, I attended George Washington University part-time (while working full-time) and earned an MPH in epidemiology and biostatistics.

Armed with the MPH, I got a job at the Maryland Department of Health as an infectious disease epidemiologist. That was also an adventure. I got the job just as the 2009 H1N1 Pandemic was about to begin. With some of the innovations I developed and helped implement, we were able to do a lot good things to keep people in Maryland informed on what was going on. This also allowed me to meet a lot of great people and collaborate on some very interesting projects.

That wasn’t enough for me, though. Again, friends, colleagues and mentors encouraged me to go back to school and get more training and education in public health. So I looked around and schools and saw that the Johns Hopkins Bloomberg School of Public Health was pretty good. I started working on a Doctor of Public Health (DrPH) degree in 2013 and finished in June of 2018.

Currently, I am working as an epidemiology program manager at a rather large local health department. I am also the editor of the History of Vaccines site, which is a project of the College of Physicians of Philadelphia. We publish information on the history and science of vaccines. You should go check it out.

Doctoral Dissertation

My doctoral dissertation was a study of homicides in Baltimore between 2005 and 2017 in order to better understand what is going on. Right off the start, I used data to show that, indeed, there is an epidemic of homicides in Baltimore that started right around April of 2015, and that intensified since the unrest following the homicide of Freddie Gray Jr. From there, the dissertation was presented in three parts.

The first part of the dissertation looked at the 3,366 homicide victims reported between January 1, 2005, and December 31, 2017. The age, gender and other individual characteristics of those victims were analyzed. Here are the major findings:

  • The majority of homicide victims were African American males between the ages of 15 and 34. Even when adjusting for population differences between age groups, this group constituted the majority of victims, and most of them were killed by firearm.
  • Female victims were less likely than their male counterparts to be killed by firearm, and they were more likely to be victims of intimate partner violence. They were also more likely to have been killed at home.
  • Most homicide victims were also unemployed or under employed, and the proportion of them who did not finish high school was significant.
  • Adjusting (accounting) for differences in the population by age group, there were eight (8) African American homicide victims for every two (2) Hispanic victims and for every one (1) White victim.

The second part looked at the neighborhood characteristics where the homicides happened. For that, I took the addresses of the homicide locations and geocoded them, overlaying them on a map. That allowed me to determine in which Community Statistical Area (CSA) the homicide happened. I then took the characteristics of the CSAs and looked for any trends and associations between those characteristics and the homicide rates. Here are the major findings:

  • Adjusting (accounting) for other characteristics, poverty is associated with an increase in the homicide rate at the CSA level. For example, a CSA with 20% of households under the poverty level had a homicide rate about 21% higher than a CSA with 10% of households under the poverty level.
  • Adjusting (accounting) for other characteristics, physical disorder (e.g. broken street lights or trash on the street) is associated with an increase in the homicide rate at the CSA level. For example, a CSA with a physical disorder index of 2 will have a homicide rate about 47% higher than a CSA with a physical disorder index of 1.
  • The 18 poorest neighborhoods had 50% of the homicides during the study period (2005 to 2017). The 18 wealthiest neighborhoods had 10% of the homicides during the study period. Both groups (the 18 poorest and the 18 wealthiest) each have about 32% of the population, so it’s not a matter of differences in the number of people in those neighborhoods.
  • Geographic hot spots of homicides varied by time. That is, where a hot spot is located in Baltimore City depended on when the homicides happened, with some hot spots disappearing and others appearing. Also, when looking only at homicides of African American men between 15 and 34 years of age, the hot spots were different than when looking at all homicides.
  • When looking at these data, it is important to take person, place and time into account. You have to look at data in four dimensions, not one or two or even three.

The third and final part looked at the available violence interventions in Baltimore City and how they address the individual and neighborhood characteristics associated with homicides described in the first two parts. Unfortunately, there is no one master list of interventions in Baltimore City. There are many organizations, directed by the government and civil society (or a combination thereof), and they are sometimes duplicating their work. Here are some of the key findings:

  • Intervention programs are not being periodically evaluated for effectiveness, for the most part. And, if they are, those results are not readily available to the public. For interventions to succeed and be effective and efficient, they need to be evaluated, and the results from those evaluations need to be used to modify the intervention.
  • Many interventions are not based on objective data, or there is no objective measure done to know if those interventions work. There may be some anecdotal evidence, but it doesn’t take into account modifying factors or confounders that could be obscuring the true association between the intervention and the outcome.
  • I also proposed a rating system for interventions. It’s only a first step in how to rate them, something I hope will get the conversation started.

If you’re interested in watching me present all of this, please check out the video below.



I’ve loved photography since I was a child. Mom used to always carry around a camera with her and take pictures of life around her. Once in a while, she’d let me take a picture. It was the neatest thing to see these moments in life captured seemingly forever. The modern era of smartphones with cameras and multi-function DSLRs has made it easier to take the picture, but finding the right moment, controlling the light, and composing the scene is still a task.

I wouldn’t say that I’m an expert, but modern technology and lots of guides on YouTube have helped.

Click here to see all my photography projects.

Click here to visit my Instagram page.

Click here to visit my Flickr page.