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

Opening the night's discussion on the economy, Harris said firmly that Biden would repeal Trump's 2017 tax cuts "on day one."

"He'll get rid of it," she said. "And what he'll do with the money is invest it in the American people and through a plan that is about investing in infrastructure, something that Donald Trump said he would do, I remember hearing about some infrastructure week, I don't think it ever happened."

"But Joe Biden will do that. He'll invest in infrastructure. It's about upgrading our roads and bridges but also investing in clean energy and renewable energy," she added.

Pence responded by attacking the state of the economy after the Obama administration and tried to tie Biden and Harris to the Green New Deal proposal.

"When President Trump and I took office, America had gone through the slowest economic recovery since the Great Depression," he said. "Because when Joe Biden was president, they tried to tax and spend and regulate and bail our way back to a growing economy."

When Harris responded again during the open discussion section, she underscored that her and Biden's plan would only raise taxes on wealthy Americans.

"We saw enough of it in last week's debate, but I think this is supposed to be a debate based on fact and truth," she said.  "And the truth and the fact is, Joe Biden has been very clear, he will not raise taxes on anybody who makes less than $400,000."

Pence argued that the Trump tax plan lowered taxes for average Americans and that a repeal would mean higher taxes for everyone, not just the wealthy.

"It would be important if you said the truth. Joe Biden said twice in the debate last week that he's going to repeal the Trump tax cuts," he said. "That was tax cuts that gave the average working family $2,000 in a tax break every single year."