Joe Biden sparked laughter at an event on Equal Pay Day on Tuesday by mistakenly calling Kamala Harris the first lady.

       The president made the gaffe when he was explaining that the vice president would not attend the event because her husband, second gentleman Doug Emhoff, had contracted Covid-19.

       “There’s been a little change in arrangement of who is on the stage because of the first lady’s husband contracting Covid,” Mr Biden said plainly, without realising his mistake.

       Only after someone from the audience pointing out that his statement meant he had caught Covid did the president correct himself.

       The attendees broke into laughter, as Mr Biden went on to joke about it.

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       “That’s right, she’s fine,” he said, gesturing to his wife Jill Biden, who was also at the event. “Second lady – the first gentleman, how about that?”

       He went on to say: "I’m Joe Biden. I’m Jill Biden’s husband and proud of it.”

       The president then called for equal pay for women and signed an Equal Pay Day executive order that encourages the government to consider a ban on federal contractors from seeking information about job applicants’ previous salaries.

       The White House confirmed that Mr Emhoff tested positive just before 6 pm and Ms Harris, who was to attend the event with Mr Biden, had tested negative.

       It came after a group of seven House Democrats tested positive attending a party in Philadelphia over the weekend. Former president Barack Obama announced on Sunday that he had tested positive for the virus while his wife Michelle Obama was negative.