Dr. Chávez holds Medical and Master of Public Health degrees, completed clinical training in Pediatrics, and advance training in Epidemiology and Preventive Medicine. In 1987, Dr. Chávez joined the staff of the national Centers for Disease Control and Prevention (CDC) as a member of the elite Epidemic Intelligence Service (EIS). Upon completion of his training as a medical detective, he joined CDC's Preventive Medicine Residency Program assigned to the Epidemiology Program Office.

In 1990, he joined CDC's Division of Reproductive Health as a Medical Officer and field assignee to the California Department of Health Services. During his initial assignment to California, Dr. Chávez served as State MCH Epidemiologist, Maternal, and Child Health Director. Dr. Chávez subsequently returned to Atlanta to serve CDC as Director of the new Division of Birth Defects and Developmental Disabilities where he directed a variety of complex and far-reaching national and international public health activities. He subsequently held a number of CDC assignments with a primary focus in supporting state and local public health efforts while on detail to the California Department of Public Health. During this time, he also served as a Temporary Advisor to the World Health Organization, Consultant to the World Bank, and expert on public health issues around the world. Dr. Chavez career at the CDC spanned a total of 30 years.

Dr. Chávez rejoined the California Department of Health Services as a CDC assignee in 2003 to serve as Associate Director and State Epidemiologist later also serving as Interim Chief of the Division of Communicable Disease Control. Dr. Chávez presently serves as the founding Chief of the Center for Infectious Diseases, Deputy Director, and State Epidemiologist in the California Department of Public Health (CDPH), coordinating the Department’s epidemiologic response to disease outbreaks and emerging health threats and administering over $800 million dollars in infectious disease prevention and treatment programs. Dr. Chavez is a frequent spokesperson for the department on media, legislative, and public forums.

Dr. Chávez has been a frequent speaker and lecturer in local, national, and international conferences. He is also an Assistant Clinical Professor at the School of Medicine, University of California Davis. Dr. Chávez has authored or co-authored 87 scientific articles in peer-reviewed journals, reports, and book chapters. He serves as a peer-reviewer for numerous clinical, public health, and epidemiology journals. Dr. Chávez has received numerous honors and awards at the state and national levels for his contributions to public health and epidemiology.