NEWARK, Del. (Reuters) -U.S. President-elect Joe Biden received his first injected dose of the COVID-19 vaccine on live on television on Monday in an effort to boost confidence in its safety ahead of its wide distribution next year.

Biden has said he would make the fight against the coronavirus, which has killed more than 315,000 Americans and infected more than 17.5 million, his top priority when he takes office on Jan. 20. At age 78, he is in the high-risk group for the highly contagious respiratory disease.

A Democrat, Biden will inherit the logistical challenges of distributing the vaccine to hundreds of millions of Americans, as well as the task of persuading people who worry its development was rushed for political reasons to take it.

His black long-sleeved shirt rolled up, Biden received the injection from Tabe Masa, Nurse Practitioner and Head of Employee Health Services at Christiana Hospital in Newark, Delaware, in front of reporters. Images were carried live on television.

After getting the shot, a dose of the vaccine developed by Pfizer Inc, Biden praised medical professionals as "heroes".

"I'm doing this to demonstrate that people should be prepared when it's available to take the vaccine. There's nothing to worry about," Biden said. His wife, Jill Biden, who got the injection earlier in the day, stood by.

But Biden also noted that the vaccine would take time to roll out and that people should listen to medical experts and not travel for the upcoming holidays if possible.

Vice President-elect Kamala Harris would likely get the vaccine next week, Biden's transition team said.

Republican President Donald Trump frequently has played down the severity of the pandemic and overseen a response health experts say was disorganized, cavalier and sometimes ignored the science behind disease transmission.

'NEW AMERICAN ECONOMY'

Efforts to limit the economic fallout on Americans from the pandemic were boosted on Sunday when congressional leaders agreed on a $900 billion package to provide the first new aid in months, with votes likely on Monday.

Biden on Monday also named additional members to his National Economic Council (NEC), rounding out his economic policymaking team with people his transition office said would help lift Americans out of the economic crisis.

David Kamin, an official in former President Barack Obama's White House, will be NEC deputy director, and Bharat Ramamurti, a former top economic adviser to Senator Elizabeth Warren's 2020 presidential campaign, will serve as NEC deputy director for Financial Reform and Consumer Protection, Biden's team said in a statement.

Joelle Gamble will be special assistant to the president for economic policy.

"This is no time to build back the way things were before — this is the moment to build a new American economy that works for all," Biden said in the statement.

Biden had already named Brian Deese, who helped lead Obama's efforts to bail out the automotive industry and negotiate the Paris climate agreement, to lead the council, which coordinates the country's economic policymaking.

Much of the fate of Biden's White House agenda will hinge on the outcome of a pair of Senate runoff elections in Georgia on Jan. 5 that will determine which party controls the upper chamber of the U.S. Congress.

Harris traveled on Monday to Columbus, Georgia, to campaign on behalf of Jon Ossoff and Raphael Warnock, the Democratic candidates locked in tight races with incumbent Republicans.

At a drive-in rally for the candidates, Harris, currently a California senator, said she would return to Washington later in the day to vote on the stimulus package.

Asked by one journalist whether there were plans to "fumigate" the White House over virus concerns before the Biden administration moved in, Harris said: "I don't have the current status for that."

Trump was briefly hospitalized in October with COVID-19, and many of his advisers and White House staff have also contracted the virus.

Ivanka Trump, the president's daughter and White House adviser, was also set to campaign in Georgia for Republican Senators David Perdue and Kelly Loeffler.

The outgoing president, making unsubstantiated claims of widespread electoral fraud, has focused on trying to overturn his election loss in recent weeks, even as daily COVID-19 deaths soared. His campaign's latest long-shot effort was a petition to the U.S. Supreme Court on Sunday that legal experts said would fail.

(Reporting by Simon Lewis and Michael Martina; Editing by Colleen Jenkins, Steve Orlofsky and Grant McCool)