Provided herein are compositions and methods for generating an immunogenic response in humans. Such compositions include an immunogenic biological agent encompassed by (ii) an agent that directs delivery of the immunogenic biological agent to the ileum of the human, wherein agent (ii) is an enteric coating (e.g., Eudragit®) that has a threshold pH 5.8-6.8. Further provided are methods for designing such compositions, e.g., for vaccines.