Dr. Sztein is an accomplished investigator in the area of immunology of infectious diseases and cytokine immunobiology. As author and/or co-author of 194 peer-reviewed scientific articles and 36 chapters, meeting reports and monographs, Dr. Sztein is a recognized international authority in the human host systemic and mucosal immune response to vaccination (with or without adjuvants) and the identification of immunological mechanisms of protection from infection in human and animal models, particularly in the field of infectious enteric diseases (e.g., those caused by S. Typhi S. Paratyphi A and B, Shigella). Other areas of interest include studies of humoral, cell-mediated (CMI) and innate immunity in volunteers and animals exposed to wild-type organisms or immunized with candidate vaccines against malaria, influenza, tularemia, hepatitis, H. pylori, and, more recently, Dengue virus, Enterotoxigenic E. coli (ETEC) and Ebola. Finally, Dr. Sztein’s group is also involved, in collaboration with Dr. Fraser, on the study of the effects of the gut microbiome on the human host response to vaccination and/or exposure to wild-type enteric pathogens.