Abstract: The present invention shows that intranasal administration of E1/E3-defective adenovirus particles may confer rapid and broad protection against viral and bacterial pathogens in a variety of disease settings. Protective responses lasted for many weeks in a single-dose regimen in animal models. When a pathogen-derived antigen gene was inserted into the E1/E3-defective adenovirus genome, the antigen-induced protective immunity against the specific pathogen was elicited before the adenovirus-mediated protective response declined away, thus conferring rapid, prolonged, and seamless protection against pathogens. In addition to E1/E3-defective adenovirus, other bioengineered non-replicating vectors encoding pathogen-derived antigens may also be developed into a new generation of rapid and prolonged immunologic-therapeutic (RAPIT).