A new generation of vaccines based on alphavirus self amplifying RNA

•Alphavirus self-amplifiying RNA (saRNA) induces more potent immune responses than conventional mRNA.•saRNA delivery can be enhanced by electroporation or conjugation with cationic lipid or polymers.•saRNA vaccines induce protective responses against human pathogens in preclinical models.•saRNA replication mediates innate immune signals that contribute to the strength of immune responses.•saRNA vaccines could be generated in a quick way to face emergent pathogens like SARS-CoV-2.