After completing a medical residency in Internal Medicine and Pediatrics, John completed a combined fellowship in Adult and Pediatric Infectious Disease at Tulane University and Louisiana State University. As a member of the Tulane University, John was Co-Investigator on several NIH-funded grants and contracts investigating Lassa fever.

During the 2013–2016 Ebola Outbreak, John served as a consultant to the WHO Global Outbreak Alert and Response Network in Sierra Leone participating in both clinical care and local staff training. As a result of these experiences, John developed a deep understanding of the difficulties of collecting data in the field and the differing interests of academic, public health and government in data collection, storage and use.