President Joe Biden threw a barb at former President Donald Trump when he was asked about Trump's COVID test results before the first presidential debate.

During the 2020 presidential election trail, the then-Republican incumbent Trump appeared for live debates with then-Democratic challenger former Vice President Joe Biden.

In a book recently published by former White House Chief of Staff Mark Meadows, an incident was recounted in which Trump showed up to the first presidential debate after receiving a positive COVID test.

As the presidential debates took place in the midst of the pandemic, both Trump and Biden had to show proof of negative COVID tests before they could attend and participate in the debate.

In Meadows' book, titled The Chief's Chief, he reveals Trump had tested positive for COVID-19 just three days before the debate, but instead of postponing the debate he chose to attend anyway.

Allegedly, Trump had gotten multiple COVID-19 tests and while one came back positive, a different test came back negative. Rather than getting more testing to determine whether he received a false negative or false positive test, Trump decided one negative test was good enough to take his chances and attend the debate, risking multiple lives in the process.

Biden, who at the time was 77 and thus high-risk for serious complications from contracting the Coronavirus, was asked yesterday what he thought about the breaking news of Trump's positive COVID test back in September of 2020.

Biden responded with major shade.

Watch the video here:

The journalist asked:

“Mark Meadows has written a book revealing that former President Trump tested positive for COVID three days before your first debate."

“Do you think the former President put you at risk?”

To which Biden responded:

“I don’t think about the former President."

Biden then turned and walked away, effectively and figuratively dropping the mic.

Twitter is loving Biden's clapback.

Trump had held a superspreader event to celebrate the nomination of now Supreme Court Justice Amy Coney Barrett on September 26 2020, just three days before the debate took place.

After the event, it was found 11 people in attendance were subsequently diagnosed with COVID-19.

Meadows recounted the day Trump and his staff were en route to a rally in Pennsylvania.

Meadows had gotten a call from the White House doctor after Trump was already aboard the Marine One aircraft.

The doctor said:

“Stop the President from leaving."

“He just tested positive for COVID.”

According to Meadows, Trump then managed to get a negative test result that same day, and then decided “to press on as if nothing had happened.”

Although the Trump campaign officials decided to keep his positive test under wraps, Meadows noted he did in fact instruct Trump's campaign staff "to treat him as positive” during the trip.

Trump has responded to Meadows' story througb proxies on social media, essentially calling it "fake news."

Trump wrote:

“A test revealed that I did not have COVID prior to the debate."