President Joe Biden on Tuesday sought to calm fears of returning to a coronavirus-induced economic shutdown amid a surge of U.S. infections with the Omicron variant, announcing plans to distribute half a billion free at-home tests beginning in January as well as other steps to prepare for further outbreaks.

"What happened was, the Omicron virus spread even more rapidly than anybody thought," Biden said at the White House, but emphasized that the country is much better prepared now than when the pandemic hit last year.

"No, this is not March of 2020. Two hundred million people are fully vaccinated. We're prepared. We know more," he said.

U.S. President Joe Biden speaks about the Omicron variant of the coronavirus at the White House in Washington on Dec. 21, 2021. (Getty/Kyodo) 

His remarks came as the Omicron variant is quickly sweeping across the United States, with data from the Centers for Disease Control and Prevention showing that the highly transmissible strain accounted for about two-thirds of the new infections last week.

In the first week of December, Omicron made up less than 1 percent of new cases, with the Delta variant being the dominant strain.

As part of efforts to keep people safe while allowing schools and the economy to remain open, Biden said his administration will purchase 500 million rapid, at-home tests, which will be made available through a website yet to be launched.

The administration also decided to ready 1,000 of the military's doctors, nurses and other medical personnel for deployment to hospitals overwhelmed by COVID-19 patients during January and February.

It will also expand the nation's capacity to inoculate the public by adding new pop-up vaccination clinics across the country, with hundreds of federal vaccinators to be deployed to enable thousands of additional appointments over the next few weeks.

While the Biden administration has been campaigning for months for people to get inoculated against the novel coronavirus, 38.5 percent of the country's total population has yet to be fully vaccinated, according to CDC data.

Biden warned that unvaccinated people face a "significantly higher risk of ending up in a hospital, or even dying."

Apparently to encourage vaccination among Republican voters, who are known as having stronger vaccine hesitancy than Democratic voters, Biden, a Democrat, mentioned during his remarks that even former Republican President Donald Trump got a booster shot for additional protection.

"Maybe one of the few things he and I agree on," Biden said.