British drugmaker AstraZeneca Plc may have provided an incomplete view of efficacy data on its COVID-19 vaccine from a large scale U.S. trial, the U.S. National Institute of Allergy and Infectious Diseases (NIAID) said on Tuesday, in a fresh setback to the shot.
AstraZeneca said a day earlier that its COVID-19 vaccine developed with Oxford University was 79% effective in preventing symptomatic illness in a large trial in the United States, Chile and Peru.
"The DSMB expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data," the U.S. agency said, referring to the independent Data Safety Monitoring Board (DSMB).
"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 U.S. emergency use authorization for the vaccine in the coming weeks.
Authorization and guidelines for use of the vaccine in the United States 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.