Johnson & Johnson vaccine

Johnson & Johnson has started shipping its first vaccine doses across the U.S., adding a third vaccine to the country's arsenal as public health officials warn of an uptick in cases.

"We've now purchased enough vaccine supplies to vaccinate all Americans," Biden said on Thursday. "Now we're working to get those vaccines into the arms of millions of people."

A study raised concerns about its effectiveness against the coronavirus variant sweeping through the country — although the data is too preliminary for definitive conclusions.