Moderator Susan Page posed the first question to Harris, revealing the first of nine topics: The coronavirus pandemic.

Noting the president's recent diagnosis, Page asked Harris, "What would a Biden administration do in January and February that a Trump administration wouldn't do?"

True to her form as a prosecutor, Harris -- the first Black woman and first Indian American to take a vice presidential debate stage -- laid out her facts, arguing the administration knew about the threat of the virus in January but didn't act soon enough.

"They were informed that it's lethal in consequence, that it's airborne, that it will affect young people," Harris said. "They knew what was happening and they didn't tell you."

Harris then said the Trump administration still doesn't have a plan.

"Well, Joe Biden does and our plan is about what we need to do around a national strategy for contact tracing, for testing, for administration of the vaccine, and making sure that it will be free for all," she said.

There was no handshake between candidates -- customary at the top of such events -- due to COVID-19 precautions. The audience, limited to under 100 attendees, applauded Pence and Harris as they took the stage.

Former Democratic 2020 presidential candidate Pete Buttigieg, who played Pence at some mock debate rehearsals for Harris, was also spotted in the audience.

Pence and Harris have taken the stage in Salt Lake City for the vice presidential debate. The candidates skipped the traditional handshake due to COVID-19 and are divided by plexiglass.

Harris' chief of staff Karine Jean-Pierre told ABC News Chief Anchor George Stephanopoulos that Harris won't spend the night fact-checking Pence on stage.

Instead, the former prosecutor will "bring the case forward" on how Biden and Harris could lead to a different America.

"This debate is about Donald Trump's failure to contain COVID-19, and not just that but to also help working families," said Jean-Pierre, adding Harris has a "very diverse team" that has prepared her for the debate.

Jean-Pierre also criticized the example Trump has set since testing positive for the novel coronavirus last week.

"You have a president right now when he left the White House, he decided that he was going to make a campaign by removing his mask. His rhetoric has been incredibly dangerous," she said. "As Joe Biden said, it's a tragedy that he believes that he was blessed to have this virus, when people are suffering."

Marc Short, Pence's chief of staff, noted that Harris, like Pence, is "also a very skilled debater and has a record as a prosecutor, so I think it will be a very engaging conversation for the American people and hopefully one that shows a clear contrast in visions between the two campaigns."

Short said Pence will argue the case that the Trump administration protected more American lives in its COVID-19 response.

With less than a month to go until the election, early voting has already begun in 33 states and at least 5.5 million votes have been cast -- hitting record numbers across the nation.

According to the United States Elections Project, spearheaded by the University of Florida's political expert, Michael McDonald, an unprecedented 5,618,155 voters have already voted and at least 69,786,179 ballots have been requested in early voting states.

The coronavirus pandemic plays a factor in explaining the large early voting numbers as well as an increase in voter interest. Voters in 2020 are more eager to cast a ballot ahead of Election Day where polling sites could be viewed as overcrowded during pandemic standards.

Seven states --- California, Colorado, Hawaii, Nevada, Oregon, Utah and Washington -- have an all-mail ballot election meaning anyone registered to vote automatically receives a ballot to their registered address.

-ABC News' Kelsey Walsh

PENCE'S CLAIM: "President Trump and I are fighting every day in courthouses to prevent Joe Biden and Kamala Harris from changing the rules and creating this universal mail-in voting that will create a massive opportunity for voter fraud."

FACT CHECK: Pence echoed Trump's attempts to cast doubt on the widespread embrace of vote-by-mail across the country this election by suggesting that universal mail-in voting could lead to massive fraud.

That is historically not true.

Kim Wyman, the Republican secretary of state in Washington -- a state that adopted statewide mail voting in 2011 -- told The New York Times in June that while any voting method could potentially be susceptible to fraud, in her experience as the chief elections official in the state, fraud with mail ballots is low.

"How do you respond to someone that makes an allegation that there's rampant fraud?" she said. "You show them all the security measures that are in place to prevent it and detect it if it does happen."

Ben Ginsberg, a Republican election guru who has spent years looking for voter fraud, wrote in a Washington Post op-ed, "Four decades of dedicated investigation have produced only isolated incidents of election fraud."

"These are painful conclusions for me to reach. Before retiring from law practice last month, I spent 38 years in the GOP's legal trenches. I was part of the 1990s redistricting that ended 40 years of Democratic control and brought 30 years of GOP successes in Congress and state legislatures. I played a central role in the 2000 Florida recount and several dozen Senate, House and state contests," he wrote. "The truth is that after decades of looking for illegal voting, there's no proof of widespread fraud."

Tom Ridge, a Republican who previously served as the governor of Pennsylvania and was the nation's first secretary of Homeland Security, previously told ABC News, "There is absolutely no antecedent, no factual basis for (President Donald Trump's) claim of massive fraud in mail voting."

--ABC News; Kendall Karson