Felix works part time as a clinical reader in the Department of Primary Care and Public Health and a public health doctor. His other job is leading the Digital Policy Unit - the joint unit between NHS England and the Department of Health and Social Care, where he is responsible for national policy and strategy for digital, data and technology in the health and care system in England.

Felix's research interests are in digital health, applied artificial intelligence, population health, behaviour change, and measuring quality and safety in healthcare systems.

Previous roles include being the board-level director of science, evidence and analytics at NICE, deputy director for science and strategic information at Public Health England, and clinical adviser to the Chief Medical Officer at the Department of Health. He also worked for the World Health Organization, where he managed their programmes on improving patient safety education in medical education and technology for patient safety. He has also been chief officer and head of secretariat of the Independent Monitoring Board of the Global Polio Eradication Initiative.

Felix trained at Oxford University (BA, BM BCh), Harvard University (MPH) and Imperial College (MBA, PhD). He was awarded a Knox Fellowship by Harvard University, the Sir John Brotherston Prize by the Faculty of Public Health in the UK, an Academic Clinical Fellowship by the NIHR, and a Harkness Fellowship in Health Care Policy and Practice by the Commonwealth Fund.