However, the US fell far short of the target set by the Trump administration to vaccinate 20 million people by the end of 2020.
By 31 December, fewer than three million had received one.
Moncef Slaoui, who had been leading the government's vaccine rollout plan, said at the time: "We know that it should be better, and we're working hard to make it better."
Mr Slaoui has since submitted his resignation at the request of President Biden.
Vaccinations have sped up considerably since the start of the year, more than doubling in Mr Trump's last week in office compared to the first week of January.
The US did achieve more than one million doses a day on a few occasions during the Trump administration.
The daily average over the week before Mr Trump left office was less than 900,000,
according to Our World in Data, although there could be a slight lag in recording daily vaccination figures.
The daily average has since risen above one million doses, and the Biden administration has come under some scrutiny for not setting a more ambitious target.
Dr Anthony Fauci, the president's top medical adviser, has said "hopefully we'll meet and surpass that goal".