Tl dr; Moderna vaccine exits Phase 1 trials successfully.

"Clinical development is a three-phase process. During Phase I, small groups of people receive the trial vaccine. In Phase II, the clinical study is expanded and vaccine is given to people who have characteristics (such as age and physical health) similar to those for whom the new vaccine is intended. In Phase III, the vaccine is given to thousands of people and tested for efficacy and safety."

">30% of drugs entering phase II studies fail to progress, and >58% of drugs entering phase III studies go on to fail"