Background: During the ongoing COVID-19 pandemic, the importance of epidemiologists and epidemiology as a science is becoming clear. An epidemiologist leads the team that deals with health emergencies and pandemics. Whatever type of epidemiologist they are, they must have specific competencies, skills, functions, and ethics.
Methods: PubMed and Google were searched for full texts of studies published in English using the key words "epidemiologist" in conjunction with definition, competencies, skills, functions, roles, types, and ethics. This narrative review included all of the literature that was retrieved. We only included the most recent and pertinent articles. Standard epidemiology textbooks were also screened for the relevant review heading.
Results: We summarized the contributions of key epidemiologists from Hippocrates to Austin Bradford Hill, as well as their competencies or skills, functions, and 16 types of epidemiologists. Finally, epidemiologists' ethics were discussed.
Conclusion: For early detection and prevention of epidemics and health disasters, effective liaison between epidemiologists, clinicians of various specialties, and policymakers is required. This is especially important in developing and developed countries where the number of epidemiologists is low and the majority work in teaching institutions where their contributions are undervalued.