President-elect Joe Biden says Americans won't be forced to take a coronavirus vaccine when one becomes available in the US.
It comes as the Centers for Disease Control (CDC) for the first time urged "universal mask use" indoors, unless when Americans are at their own home.
The CDC said the US had "entered a phase of high-level transmission" of the virus, reports the BBC.
On Friday the US recorded over 2,500 deaths and nearly 225,000 new cases.
It has confirmed 14.3 million cases and more than 278,000 deaths.
Mr Biden - who is due to take office on 20 January - also said he expected his inauguration to be a scaled-back event without large crowds because of coronavirus concerns.
"My guess is there'll still be a platform ceremony but I don't know how it's all going to work out," he said.
What is Biden's policy on vaccines?
Pfizer, which says its vaccine has been shown to be 95 per cent effective in clinical trials, and Moderna, which says its jab is 94 per cent effective, have both applied to the Food and Drug Administration to distribute their drugs in the US.
The UK on Wednesday became the first country in the world to approve the Pfizer vaccine.
Earlier on Friday Vice-President Mike Pence said during a visit to Atlanta's CDC that federal approval for a Covid-19 vaccine could be "a week-and-a-half away."
Speaking in Wilmington, Delaware, the US president-elect said it would not be necessary to make a coronavirus vaccine mandatory.
"I will do everything in my power as president to encourage people to do the right thing and when they do it, demonstrate that it matters," he said.
The Pew Research Center says just 60 per cent of Americans are currently prepared to take a coronavirus vaccine, up from 51 per cent who said the same in September.
On Thursday Mr Biden told CNN he would be happy to take a vaccine in public to allay potential concerns about its safety. Three former presidents - Barack Obama, George W Bush and Bill Clinton - have said they are also prepared to be inoculated publicly.
Mr Biden has also reiterated his call for Americans to wear a mask for 100 days - a measure that he said combined with vaccine distribution would see deaths "drop off the edge".
"My hope is they will then be inclined to say it's worth the patriotic duty to go ahead and protect other people," Mr Biden said.