Tal Zaks, chief medical officer at Moderna, told The BMJ that the company’s trial lacks adequate statistical power to assess those outcomes. “The trial is precluded from judging [hospital admissions], based on what is a reasonable size and duration to serve the public good here,” he said.
Hospital admissions and deaths from covid-19 are simply too uncommon in the population being studied for an effective vaccine to demonstrate statistically significant differences in a trial of 30 000 people. The same is true of its ability to save lives or prevent transmission: the trials are not designed to find out.
