President-elect Joe Biden has implored all Americans to wear face masks as he warned of a "dark winter" in the US due to the coronavirus pandemic.
Expressing a message of unity, he said: "I implore you, wear a mask. Do it for yourself. Do it for your neighbour. A mask is not a political statement. But it is a good way to start pulling the country together.
"The goal of mask wearing is not to make your life less comfortable, or to take something away from you. It is to give something back to all of us, a normal life."
Mr Biden also claimed that many lives could be saved - in a nation which has been hit by deep divisions during the presidential campaign.
He said: "It doesn't matter who you voted for, we can saved tens of thousands of lives if everyone wears a mask in the next few months."
During the pandemic, there have been more than 9.9 million coronavirus cases and over 237,000 deaths in the US - the highest of any country in the world.
And the president-elect warned that 200,000 more Americans could die before an effective COVID-19 vaccine is widely rolled out.
Mr Biden, who was frequently seen wearing a mask during the White House race in stark contrast to his rival Donald Trump, said the challenge facing the country over coronavirus is still "immense" and "growing" - despite news of a vaccine breakthrough.
The one being developed by Pfizer and BioNTech has been found to be 90% effective in preventing people from getting the virus.
Mr Biden has welcomed the announcement but he cautioned that Americans still need to take mask wearing and social distancing seriously.
And he said any effective vaccine would not be widely available for many months to come.
Mr Biden, who won't officially become America's next leader until his inauguration in January, has been briefed on the epidemic by his newly-appointed taskforce of medical experts.
He and vice president-elect Kamala Harris took notes during the virtual briefing at a theatre in Wilmington, Delaware, as the members introduced themselves.
The taskforce of more than a dozen experts has been set up to provide advice to the next commander-in-chief about how to tackle soaring COVID-19 cases and deaths.
The first to speak at the briefing was Dr David Kessler, a former Food Drug Administration commissioner under ex-presidents George H W Bush and Bill Clinton.
He is co-chairing the taskforce with Dr Vivek Murthy, who served as surgeon general under former president Barack Obama.
Dr Marcella Nunez-Smith, a Yale University associated professor and associate dean, is also a co-chair. Her research focuses on promoting health care equality for marginalised populations.
Also part of the group is Rick Bright, a whistleblower who was demoted after criticising the Trump administration's response to the pandemic. Mr Bright had been head of the Biomedical Advanced Research and Development Authority.
Mr Biden has said the experts will "help take the Biden-Harris COVID plan and convert it into an action blueprint".
He pledged: "That plan will be built on a bedrock of science. It will be constructed out of compassion, empathy, and concern. I will spare no effort - or commitment - to turn this pandemic around."
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Mr Biden made coronavirus a major feature of his victory speech at a drive-in rally in Delaware on Saturday night, after finally being projected to win the 2020 election earlier in the day.
"We cannot repair the economy, restore our vitality, or relish life's most precious moments - hugging a grandchild, birthdays, weddings, graduations, all the moments that matter most to us - until we get this virus under control," he said.
The president-elect's website says his administration will double the number of drive-through testing centres, increase PPE provision and expand the Centres for Disease Control and Prevention's monitoring of China to prevent incoming threats.
It is a markedly different tone from Mr Trump, who is still refusing to concede the election and has been criticised for his actions and comments on COVID-19.
He caught the disease in October, following a White House event to announce the nomination of a new Supreme Court justice where most attendees sat packed together not following social distancing rules nor wearing masks.
