Although mRNA is a new topic for most of us, scientists have been studying and working with mRNA for decades. mRNA has been used specifically in cancer research and in vaccines for flu, Zika, and rabies. Medical experts like mRNA vaccines because they can be developed in a lab with materials that are readily available, which means the process can be quicker than developing traditional vaccines.
Those decades of research and innovation meant that the mRNA vaccine technology was ready when we needed it most.
SOURCE: https://publichealth.jhu.edu/2021/the-long-history-of-mrna-vaccines (Johns Hopkins)