Dan Salmon's primary research and practice interest is in optimizing the prevention of childhood infectious diseases through the use of vaccines. He has focused on post-licensure vaccine safety and the factors associated with parental decisions to vaccinate, or not vaccinate, their children. He has conducted studies examining the rates of vaccine refusal, the reasons why parents refuse vaccines, the impact of health care providers and local and state policies on vaccine refusal and the individual and community risks of unvaccinated children. He joined the faculty of the Johns Hopkins Bloomberg School of Public Health after serving as the director of vaccine safety at the National Vaccine Program Office, where he was responsible for coordinating federal vaccine safety activities. He holds master's and doctoral degrees in public health from Emory and Johns Hopkins universities, respectively.