Development of mRNA vaccines against infectious disease is unprecedented in many ways. [According to] a 2018 publication sponsored by the Bill and Melinda Gates Foundation … Unprecedented represents a category of vaccine against a disease for which there has never before been a suitable vaccine.… nprecedented vaccines are expected to take 12.5 years to develop. Even more ominously, they have a 5% estimated chance of making it through Phase II trials (assessing efficacy) and, of that 5%, a 40% chance of making it through Phase III trials (assessing population benefit). In other words, an unprecedented vaccine was predicted to have a 2% probability of success at the stage of a Phase III clinical trial. As the authors bluntly put it, there is a “low probability of success, especially for unprecedented vaccines.”