A US health agency has called into question data provided by AstraZeneca following its Covid-19 vaccine trial in the United States.
The Data and Safety Monitoring Board said it had concerns that the UK firm had used "outdated information" that could have offered an incomplete view of the efficacy of the vaccine.
AstraZeneca reported on Monday that a trial of 30,000 people in the US had found the jab was 79% effective at preventing symptomatic cases of coronavirus among all adults.
The company now seeks authorisation from the Food and Drug Administration and the Centres for Disease Control and Prevention to roll out the vaccine across the US.
Independent advisors will debate the evidence publically before a decision is made.
The AstraZeneca trial found there were no severe illnesses or hospital admissions among the vaccinated volunteers.
It also concluded that the vaccine posed no increased risk of blood clots or serious side-effects.
The positive findings were seen as a key milestone towards clearance of the Oxford-AstraZeneca for use in the US.
