Matthew M. Zahn, MD, deputy health officer of the OC Health Care Agency, has worked in local public health for 20 years, including overseeing immunization and communicable disease control programs for a diverse county of 3.2 million residents. He led the public health response to community outbreaks of vaccine-preventable diseases including measles, mumps, meningococcal disease, hepatitis A, H1N1 influenza, pertussis, and COVID-19. Zahn also supervised the agency’s response to local outbreaks of multi-drug resistant organisms including Candida auris. He has been active at the local, state, and national levels in advocating for support of local public health’s role in protecting communities against infectious diseases. He served as ACIP liaison for the National Association of County and City Health Officials and continues to serve as a pediatric infectious disease clinician at the Children’s Hospital of Orange County.