The present invention relates to a vaccine composition comprising:(i) a peptide hydrogel that is a liquid at room temperature and a gel at physiological pH, physiological salt concentrations and/or physiological temperatures; and (ii) one or more antigens; wherein the peptide hydrogel comprises a self-assembling peptide selected from the group consisting of RAD16-I ((RADA)(4); (SEQ ID NO:2)), RAD16-II ((RARADADA)(2); (SEQ ID NO:3)), KFE-8 ((FKFE)(2); (SEQ ID NO:4)), and KLD-12 ((KLDL)(3)); (SEQ ID NO:5)).