The present invention relates to prime-boost regimens that involve the administration of at least one mRNA construct, such as the use of such constructs in “boost” administration subsequently to “prime” administration of certain other antigenic composition(s). Such inventive regimens may, in particular, be useful for the induction of an immune response in a subject, and/or the vaccination of such subject against infection from one or more pathogens, and/or the treatment or prevention of one or more diseases or conditions, including a tumour or cancer, allergy or autoimmune conditions, and/or a disease or condition associated with infection from a pathogen. The present invention further describes methods, uses, vaccination compositions, kits and packaged vaccine components related to or useful for one or more of such regimens.