“We urge the company to work with the DSMB to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible.”
The request cast doubts over the company's plan to seek US emergency use authorisation for the vaccine in the coming weeks.
Authorisation and guidelines for use of the vaccine in the US will be determined by the Food and Drug Administration and Centers for Disease Control and Prevention after thorough review of the data by independent advisory committees, said the NIAID, part of the National Institutes of Health.
AstraZeneca did not immediately respond to a Reuters request for comment.
Hailed as a milestone in the fight against the Covid-19 pandemic when it emerged as a vaccine contender last year, the AstraZeneca shot has been dogged by doubts over its efficacy, dosing regimen and possible side effects.