US President-elect Joe Biden has set a goal of 100 million Covid vaccinations in his first 100 days in office.
He said his first months in office would not end the outbreak and gave few details on rollout strategy but he said he would change the course of Covid-19.
Introducing his health team for when he takes office on 20 January, he urged Americans to "mask up for 100 days".
On Tuesday, a report paved the way for a Pfizer/BioNTech vaccine to be approved and rolled out for Americans.
President Donald Trump meanwhile attended a summit at the White House of his Covid vaccination programme called Operation Warp Speed and hailed the expected approval of vaccines.
The US has recorded more than 15 million cases of infection in the pandemic so far and 285,000 deaths, according to Johns Hopkins University research, both global highs.
Many parts of the country are seeing peak infections, with record numbers of people in hospital, with some experts blaming travel by millions over the recent Thanksgiving holiday.