COVID-19 updates: Classes in Chicago canceled for 4th day

The FDA is warning people not to swab their throats as part of an at-home COVID-19 test.

In a statement obtained by ABC News, the FDA said that is not how the tests were designed and it could pose a safety concern.

"The FDA advises that COVID-19 tests should be used as authorized, including following their instructions for use regarding obtaining the sample for testing," the statement said.

Social media posts promoting at-home COVID-19 rapid test swabbing techniques claim that throat swabs collect a better sample. However, this hasn't been proven for currently authorized tests.

- ABC News' Sony Salzman

President Joe Biden announced Tuesday afternoon that he was doubling the federal government's purchases of Pfizer's COVID-19 antiviral pill, from 10 million to 20 million treatment courses.

"They’re a gamechanger and have the potential to dramatically alter the impact of COVID-19, the impact it's had on this country and our people,” Biden said.

He also warned that those who remain unvaccinated "will die" during the ongoing omicron surge.

“So there's no excuse, no excuse, for anyone being unvaccinated,” Biden said.

-ABC News' Ben Gittleson

Data released by the Centers for Disease Control and Prevention from the weekend shows that the U.S. is now averaging nearly half a million new cases a day.

About a year ago, the U.S. was reporting an average of about 216,000 new cases a day. However, compared to last winter, hospital admissions and daily deaths are notably lower.

Over the last week, the U.S. reported more than 3.4 million new cases -- roughly averaging out to nearly six Americans testing positive every second.

-ABC News' Arielle Mitropoulos

At least three major health systems in Florida said half of their COVID-19 patients were originally admitted to hospitals for other reasons. 

During a briefing about the pandemic in Jacksonville on Tuesday, Gov. Ron DeSantis said about 50% of COVID hospitalizations at Orlando Health and Miami Jackson Health and 60% at Tallahassee Memorial were being treated for other reasons and learned were positive for the virus during their stays.

In a tweet, Miami Jackson Health said its exact figure is 53%.

DeSantis called on the U.S. Department of Health and Human Services to change the way it reports COVID-19 hospitalizations.

"It really isn't instructive if you have something that is very widespread and mild, and it's catching people as they go into the hospital with positive tests, but they're not actually having any clinical diagnosis," he said.

It comes one day after New York Gov. Kathy Hochul said hospitals in her state would be surveyed about how many patients were being admitted to hospitals for COVID as opposed to with COVID.

-ABC News' Will McDuffie