Denise DeRoeck, MPH, has more than 25 years of experience in global public health, including 13 years focusing on immunization and vaccines in developing countries. Her work has covered a broad range of issues related to immunization, from decision-making and implementation concerning the introduction of new vaccines, to immunization financing and procurement. She has recently prepared the new WHO vaccine introduction guidelines (Principles and considerations for adding a vaccine to a national immunization programme), which adds new emphasis on the impact of vaccine introductions on health systems and immunization programs, based on recent research. In the area of cholera, her experience includes writing a background paper for the WHO Strategic Advisory Group of Experts (SAGE) that led to new WHO recommendations on the use of cholera vaccines; conducting face-to-face policymaker surveys in 10 countries concerning enteric vaccines (cholera, typhoid and Shigella); helping to conduct a country investment case for cholera vaccination in Bangladesh; and assisting GAVI with the start-up of its cholera vaccine stockpile program.