AstraZeneca Sees COVID Vaccine Trial Dropouts Due To Pfizer, Moderna Authorizations In US

Approximately 9% of subjects have withdrawn from the 32,000-person trial because they were eligible to receive one of the mRNA vaccines in the US; AstraZeneca expects limited impact on efficacy assessment but is working on a potential plan for crossover of all participants to try to keep as many in the study as possible for safety follow-up.