Dr. Vann joined CBER as a research chemist in 1979, after several years as a von Humboldt Fellow at the Max-Planck Institute in Freiburg, Germany, where he determined the structure of capsular polysaccharides of pathogenic Escherichia coli. Since his appointment at CBER, he has served as the primary expert in polysaccharide chemistry and as such has made major contributions to the development and licensure of polysaccharide based vaccines. He was appointed to the position of Chief of the Laboratory of Bacterial Toxins in 1996, where he was responsible for supervising the research and review responsibilities for products related to diphtheria, tetanus, and botulinum toxins. In 2006 he was appointed as Chief of Laboratory of Bacterial Polysaccharides. As Chief of the Laboratory of Bacterial Polysaccharides, he has supervisory responsibility for the scientific and regulatory work of several principal investigators that is related to encapsulated pathogens. He is also a principal investigator in the Laboratory and manages a research program on the glycobiology of pathogenic bacteria.