Being a doctor and caring about social issues and public health are not oppositional. On the contrary, they are complementary. A good doctor has a good understanding of social issues and public health and how they intersect with the practice of medicine. And great preparation for public health can involve training in medicine.
First of all, there are MANY MPH programs that are designed for clinicians; they are designed to take one year, and/or are designed to be completed while the clinician works full-time. So you can get an MPH after you finish your MD, possibly while you practice. I studied public health in graduate school and many of my classmates were recent MD graduates (or, in one case, a classmate who took a leave of absence after his second year of medical school to get an MPH. He returned to medical school and finished, and now he’s a physician).
Secondly, there are a LOT of careers that blend the two. Honestly, just being a practicing doctor fuses the two, since a good doctor understands how social issues impact the lives of their patients and intersects with their patients’ ability to follow medical advice and stay healthy. But for more closely related work, there’s
-practicing medicine in a hospital in a designated low-income or critical access hospital;
-practicing in free community health clinic
-serving in a school-based clinic (there are many low-income schools that have clinics to serve students who may not otherwise have health insurance);
-practicing in a rural health center or clinic;
-practicing on a Native American reservation;
-working in a substance abuse treatment or harm reduction center;
-working in a traveling clinic/van clinic;
-working with an international organization like Doctors Without Borders;
-joining the U.S. Public Health Service Commissioned Corps
In addition to roles as an actual practicing medical provider, there are other roles where you may not be giving individual patient care but that require or really benefit from medical expertise:
-rising to medical leadership positions in clinics or hospitals/hospital systems, like Chief Medical Officer or a similar role
-retraining and working as an epidemiologist, either for a state or city health department or for a national agency like the CDC (check out the Epidemic Intelligence Service)
-teaching a class or two as an adjunct professor in a public health department (but you’d likely need the requisite MPH or some experience).
-going to work at a public health related nonprofit, governmental or nongovernmental organization (there are a wide range of these kinds of roles)
Also keep in mind that you don’t have to work one career in your whole life. With an MD, it’s possible for you to practice medicine for 7 years, decide you want to go into public health, get an MPH, and make a career transition into community mental health education. Or you can do multiple things: maybe you practice medicine at a small rural clinic while also teaching afternoon classes to the local community on public health topics. And so forth.
And healthcare providers run for office frequently! There are many members of our national Congress that are former doctors and nurses and other healthcare providers. That expertise in medicine (however you apply it) is useful when thinking about healthcare related legislation. There are also ways to serve in government and public life without being elected: you can be appointed to any number of health-related agencies, committees, and boards, sometimes while you work your full-time job. For example, my state appoints citizens to the State Board of Health and they all hold outside jobs.