https://www.bmj.com/content/371/bmj.m4037
Will covid-19 vaccines save lives? Current trials aren’t designed to tell us
Will covid-19 vaccines save lives? Current trials aren’t designed to tell us
Yet the current phase III trials are not actually set up to prove either (table 1). None of the trials currently under way are designed to detect a reduction in any serious outcome such as hospital admissions, use of intensive care, or deaths. Nor are the vaccines being studied to determine whether they can interrupt transmission of the virus.
...
What about Hotez’s second criterion, interrupting virus transmission, which some experts have argued17 should be the most important test in phase III studies?
“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.”
He repeatedly emphasised these “operational realities” of running a vaccine trial. “Every trial design, especially phase III, is always a balancing act between different needs,” he said. “If you wanted to have an answer on an endpoint that happens at a frequency of one 10th or one fifth the frequency of the primary endpoint, you would need a trial that is either 5 or 10 times larger or you’d need a trial that is 5 or 10 times longer to collect those events. Neither of these, I think, are acceptable in the current public need for knowing expeditiously that a vaccine works.”