Abstract: An immunobooster capable of delivering an immunogen to an individual or animal in a controlled release manner is described. The immunobooster contains an immunogen/hydrophobic polymer matrix with a swelling agent such that the swelling agent can swell in an aqueous environment and burst the matrix. The immunogen is released in a pulsed release manner after a desired time interval has elapsed subsequent to administration of the immunobooster. The immunobooster eliminates the need for multiple administrations of immunogen in order to build lasting immunity. Also described are methods of preparing and using the immunobooster, and kits containing the immunobooster.