AstraZeneca Plc and the University of Oxford, among the front-runners in the quest to deliver a Covid-19 vaccine, face mounting questions about their trial results after acknowledging a manufacturing error.
While an announcement Monday by Astra and Oxford showed their shot was 70% effective on average in a late-stage study, the scant details released by the U.K. partners have sparked worries about whether regulators would clear it. In a later statement, Oxford said a difference in manufacturing processes led to some participants being given a half dose instead of a full one.
