In October of last year (2020), Tal Zaks, chief medical officer at Moderna (he will be leaving that position in September), said that the trials were not designed to determine whether the vaccines could reduce serious illness or reduce transmission. They would have had to be larger and longer.
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.
“Our trial will not demonstrate prevention of transmission,” Zaks said, “because in order to do that you have to swab people twice a week for very long periods, and that becomes operationally untenable.”
– Will Covid-19 Vaccines Save Lives? Current Trials Aren’t Designed To Tell Us, British Medical Journal, 21 October 2020
Those trials are all we have, and all we will ever have, since the control groups were given the vaccine. Anyone who has said, or is saying that these vaccines reduce serious illness or reduce transmission is not basing those claims on the results of a clinical trial.