This invention provides a family of immunogenic compositions and vaccines, each containing a target antigen or antigen mixture, and an oligopeptide adjuvant, exemplified by the tripeptide Ile-Glu-Trp. The adjuvant has a low side effect profile, and may be especially effective in generating a rapid and specific Th1 or cellular immune response where the antigen is poorly immunogenic, or the patient is elderly or immunocompromised. In some circumstances, effectiveness of the vaccine can be substantially enhanced by administering follow-on injections of the tripeptide alone. The vaccine has been used to generate an enhanced response to multiple strains of influenza simultaneously, and is suitable for preventing or treating other infectious and disease conditions.
