WASHINGTON, Dec. 21 (CNA) - US President-elect Joe Biden received his first injected dose of the COVID-19 vaccine live on television on Monday (Dec 21) 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 Mase, 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.

He credited the scientists who worked on the vaccines, adding: "I think that the (Trump) administration deserves some credit, getting this off the ground with Operation Warp Speed."

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.