At key meeting, FDA advisors debate if early coronavirus vaccine approvals may compromise trials

Coronavirus vaccine studies run by Pfizer and Moderna are expected to soon deliver results that show whether or not the experimental shots truly work. If data are positive, the companies will likely ask the Food and Drug Administration for emergency clearance.

Such an early approval, should one be granted, would be a turning point in a pandemic that looks far from over. But an emergency use authorization, or EUA, could also raise thorny questions about how the companies complete their trials, and might complicate studies of other vaccines.