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Biden was discussing the latest on combating the pandemic from his home when it was interrupted by a cough.
"Excuse me," Biden said after he coughed into his hand.
"You know, you're supposed to cough into your elbow," Tapper told the former vice president as he himself demonstrated with his elbow. "I learned that, actually, covering your White House."
"Actually, that's true," Biden conceded. "But fortunately, I'm alone in my home, but that's OK. I agree you're right."
The CNN anchor, however, doubled down on the proper etiquette lesson.
"It's kinda just old school to do it with your hand," Tapper added while demonstrating with his elbow again. "Do it into your elbow. You're supposed to do it."
"Thank you," Biden grinned.
Biden recently launched a daily live-stream address of his own updates on the coronavirus outbreak as the 2020 Democratic primary was brought to a halt by the escalation of the virus. Both he and Sen. Bernie Sanders, I-Vt., had been taken off the campaign trail as public gatherings have been ordered to shut down by state governments. President Trump also had to cancel his campaign rallies.