During the first open discussion session, Page asked Harris if she would take a COVID-19 vaccine if it was approved by the Trump administration.

"If the public health professionals -- if Dr. Fauci, if the doctors tell us that we should take it, I'll be the first in line to take it, absolutely," Harris said. "But if Donald Trump tells us I should take it -- that we should take it, I'm not taking it."

Page tried to move on to the next topic -- the role of the vice president -- but Pence used his uninterrupted two minutes to respond to Harris' comment on a potential vaccine and to criticize how the Obama administration handled the Swine Flu or H1N1 pandemic of 2009.

"We have five companies in phase three clinical trials and we're right now producing tens of millions of doses," the vice president said.  "So, the fact that you continue to undermine public confidence in a vaccine, if a vaccine emerges during the trump administration, I think is unconscionable."

"And senator, I just ask you, stop playing politics with peoples' lives. The reality is, that we will have a vaccine, we believe, before the end of this year," he added.

In light of the president's recent diagnosis, Page directly asked Pence, "How can you expect Americans to follow the administration's safety guidelines to protect themselves from COVID when you at the White House have not been doing so?"

"Well, the American people have demonstrated over the last eight months that, when given the facts, they're willing to put the health of their families and their neighbors and people they don't know first," Pence said.

Pence also addressed the Sept. 26 Rose Garden event during which social distancing and masks weren't enforced and after which several White House officials tested positive.

"Many of the people who were at that event, Susan, actually were tested for coronavirus, and it was an outdoor event which all of our scientists regularly and routinely advise," Pence said. "The difference here is, President Trump and I trust the American people to make choices in the best interest of their health."

Pence defended the White House's response to the COVID-19 pandemic, saying that Trump "has put the health of America first." Pence pointed to the administration's early ban on travel to China, testing efforts and the efforts to research and administer a vaccine.

Pence also went after the plan the Biden campaign released to combat coronavirus, saying "it reads an awful lot like what President Trump and I, and our task force, have been doing every step of the way."

He said that the plan "looks a little bit like plagiarism," because of its similarity to the White House Coronavirus Task Force plan.

Harris hit back at Pence, citing the revelations that Trump downplayed the coronavirus to prevent panic.

"I want to ask the American people, how calm were you when you were panicked about where you were going to get your next roll of toilet paper, how calm were you when your kids were were sent home from school? How calm were you when your children couldn't see your parents because they were afraid they could kill them?" she said.

Trump's re-election campaign is looking to have the president return the campaign trail early next week, despite his COVID-19 diagnosis last Thursday and hospital stay over the weekend.

The campaign was forced to cancel five previously announced rallies due to the president's testing positive. Multiple sources tell ABC News the Trump team has begun working to nail down details for the president's return to the campaign trail and has considered an event -- possibly in Pennsylvania -- as early as next Monday.

ABC News' Will Steakin, Katherine Faulders and John Santucci

Pence pivoted from a question on pre-existing conditions to press Harris for an answer on whether or not she and Biden supported adding additional seats to the Supreme Court.

"I think the American people would really like to know, if Judge Amy Coney Barrett is confirmed to the Supreme Court of the United States, are you and Joe Biden, if somehow you win this election, going to pack the Supreme Court to get your way?" the vice president asked.

Harris used her first answer to attack the Trump administration for rushing a vote on Barrett's nomination by bringing up a Republican the president often compares himself to -- Abraham Lincoln.

"It was 27 days before the election, and a seat became open on the United States court. Abraham Lincoln's party was in charge of not only the White House but the Senate," she said, referring to the 1864 election.

"But Honest Abe said it's not the right thing to do," Harris added. "The American people deserve to make the decision about who will be the next president of the United States, and then that person can select who will serve for a lifetime on the highest court of our land. And so, Joe and I are very clear: the American people are voting right now, and it should be their decision about who will serve on this most important body for a lifetime."

MORE: Most say wait on Ginsburg seat, while opposing packing the court: Poll

Pence used her non-answer to say that Biden and Harris would pack the Supreme Court and that he and Trump would protect the current number of justices on the court. 
"The American people deserve a straight answer," he said. "And if you have not figured it out yet, the straight answer is they are going to pack the Supreme Court, if they somehow win this election.

Harris responded that Republican efforts to get more conservatives confirmed as federal judges amounted to packing the court, noting that of the 50 people the president nominated to the Court of Appeals none were Black. She did not state her position on adding seats to the U.S. Supreme Court.