WASHINGTON -- US President-elect Joe Biden stressed the importance of wearing masks in his first press conference since declaring his victory, insisting the simple act of wearing a mask may save tens of thousands of lives.

The call came only hours after an American pharmaceutical company, Pfizer, said an early analysis of data from its coronavirus vaccine trial showed the vaccine to be more than 90 percent effective.

"As you work toward a safe and effective vaccine, you know the single most effective thing we can do to stop the spread of COVID is (to) wear a mask," Biden told a press conference in Wilmington, Delaware, where he declared victory in the presidential election against President Donald Trump on Saturday.

Biden's remarks marked a sharp contract from those of Trump, who has consistently refused to wear a mask in public, and up until the very last minute of the presidential election, held on Tuesday, claimed the country was "rounding the corner" on the COVID-19 pandemic.

The US, however, has been seeing gains in its new daily infection cases.

As of Sunday, more than 9.8 million Americans have been infected with the new coronavirus, while more than 236,000 have died, according to the US Centers for Disease Control and Prevention (CDC). The United States has one-fifth of the worldwide coronavirus cases, but only 4 percent of the world's population.

"The head of the CDC warned this fall that for a foreseeable future, (a) mask remains the most potent weapon against the virus.

Today's news does not change that urgent reality," said Biden.

The president-election also put together a new COVID-19 transition advisory board, which he said will help put his COVID plans into action as soon as he is sworn in.

However, he noted those actions will take time.

"I won't be president until January 20 but my message today to everyone is this. It doesn't matter who you voted for, or where you stood before election day. It doesn't matter your party, your point of view, we can save tens of thousands of lives if everyone would just wear a mask for the next few months," Biden said at the press conference, also noting the vaccine, even if approved, "will not be widely available for many months yet to come."

He insisted masks can save lives in the meantime.

"You know, maybe we will save the life of a person who stocks a shelf to a local grocery store. Maybe saves the life of a member of your place of worship. Maybe saves the lives of one of your children's teachers. Maybe saves your life. So please, I implore you, wear a mass. Do it for yourself. Do it for your neighbor," Biden said.

Also to those who refuse to wear a mask for political reasons, the president-elect insisted a mask is not a political statement.

"I want to be very clear. The goal of mask wearing is not to make your life less comfortable or take something away from you. It is to give something back to all of us: a normal life. Our goal is to get back to normal as fast as possible, and mask are critical and doing that," said Biden. (Yonhap)