“Naked” Self-Amplifying RNA Vaccine Shows Promise As A Booster, Induces Strong Cytotoxic T-Cell Responses Here we describe a "naked" self-amplifying RNA vaccine that, unlike conventional mRNA vaccines, does not require a lipid nanoparticle formulation or pseudouridine substitutions. Preliminary results suggest the vaccine induces robust CD8+ T cell responses and is effective in prime/boost regimens.