Washington, Oct 26 (IANS): US President Joe Biden has received an updated Covid-19 booster shot.

"This virus is constantly changing," Biden said on Tuesday afternoon at the Eisenhower Executive Office Building near the White House. "New variants have emerged here in the US and around the world."

"Your old vaccine or your previous Covid infection will not give you maximum protection," he warned.

More than 20 million Americans have received updated Covid-19 vaccine so far, Xinhua news agency reported, citing the White House.

"Not enough people are getting it," Biden stressed. "The weather is getting colder. People will spend more time indoors. And contagious viruses, like Covid, are going to spread considerably more easily."

The US has reported 97 million Covid-19 cases, along with more than 1 million deaths, according to data from Johns Hopkins University.

Nearly 400 people are still dying each day from the virus in the country. Biden said, "that number is likely to rise this winter."