>A second generation of Covid-19 mRNA vaccines is making its way onto the scene. Common to many of them is the use of self-amplifying RNA technology, which maximizes antigen expression. Now, researchers have developed a self-amplifying RNA vaccine with a number of exciting new characteristics. First, it doesn’t require any of the nucleobase modifications that conventional mRNA vaccines depend on for improved stability. Second, it simply uses “naked” RNA injected directly without a protective lipid nanoparticle. Third, the vaccine is designed to be administered into the outer layer of the skin —the dermis— for improved cellular immunity. And fourth, it has been optimized to suit the temperature range of the surface of the body, rather than the core of the body.