The United States is expected to approve the low-cost AstraZeneca/Oxford vaccine in April, a senior official said, more than three months after Britain's green light on Wednesday.
Moncef Slaoui, the chief advisor to Operation Warp Speed, the military-led US effort for vaccines, told reporters that US trials and assessments would be complete for approval "sometime in early April."
"Several tens of millions of doses will have been manufactured... and therefore will be available for use if the data supports its approval," he said.
He did not allege that Britain rushed its decision and praised Britain's MHRA regulatory agency as "science-based."
"Therefore I am not raising any question as to the decision that they have made," he said.
"Having said that, the requirements of the decision process as we have built it here in the US is what I can really comment on."
Slaoui also voiced hope for approval in the first half of February of the Janssen vaccine by Johnson & Johnson, which in contrast to the initially approved vaccines comes in a single dose.