And the FDA boss said that he is ready to take the Covid vaccine as government officials insist it is safe for the American public.
"I will absolutely take this Covid-19 vaccine,” said FDA commissioner Stephen Hahn as he insisted no corners were cut on its review.
"Science and data guided the FDA's decision. We worked quickly because of the urgency of this pandemic, not because of any other external pressure,” he added.
There have been an estimated 16 million cases of Covid in the US and more than 296,000 people have died since the beginning of the pandemic.
Mr Hahn went on to say that Donald Trump had not threatened to fire him if the FDA did not approve the vaccine, and called those reports “inaccurate.”
Following the approval of the vaccine, Mr Trump called it a “medical miracle” that will “save millions of lives and end the pandemic once and for all.”
The outgoing president said that the first doses of the vaccine would be given “in less than 24 hours.”
The emergency authorization does not give Pfizer full approval for their drug and they will be required to file a separate application for it to be fully licensed.
“This is a really monumental moment for us,” emergency physician Dr Leana Wen told CNN on Friday.
"We need to take a moment, I think, and just consider that we are having this mass casualty event every day here in the US.
"But now we have this vaccine developed in record time that can in time really save us and save our country and save the world from this awful pandemic.”
Despite the authorisation it will still take months for most Americans to receive the vaccination.
Health and Human Services Secretary Alex Azar told ABC News that around 20 million Americans should be vaccinated by the end of December, 50 million by the end of January and at least 100 million people should have it by the end of February.
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