RNA-based influenza vaccines offer several advantages over current inactivated influenza vaccines (such as reduced production times, elimination of egg- and cell-based propagation steps, and the potential for rapid updating in the event of antigenic drift). There are numerous different mRNA-based influenza vaccines in development, with phase 1 clinical trials reported for some (such as https://pubmed.ncbi.nlm.nih.gov/31079849/ ). More information on recent flu vaccine advancements is available here: https://www.cdc.gov/flu/prevent/advances.htm