Their definition seems pretty close to that of Google: https://www.google.com/search?q=define+vaccine

> a substance used to stimulate the production of antibodies and provide immunity against one or several diseases, prepared from the causative agent of a disease, its products, or a synthetic substitute, treated to act as an antigen without inducing the disease

But to be fair, at this point, I don't know why we discuss mRNA vaccines, there's been traditional vaccines available for people to take as well such as J&J and Novavax. So even if you don't want to take risk with mRNA since its a newer mechanism to use for vaccines, one can take J&J or Novavax instead.