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

In light of President Trump's positive COVID-19 diagnosis and subsequent concerns from Harris' team, the Commission on Presidential Debates agreed to add additional safety precautions to Wednesday's debate at the University of Utah.

Unlike last week's presidential debate, everyone in the audience will be required to wear a face mask or covering and those who don't will be escorted out of the venue.

"They've got to wear a mask, and if they take their mask off they're gonna be escorted out, and I don't care who they are, they'll be escorted out," Frank Fahrenkopf, chairman of the Commission on Presidential Debates, told ABC News.

Harris and Pence will be tested prior to the debate, according to the commission, a change from the presidential debate when campaigns were responsible for testing their candidates and traveling parties.

And the candidates will be separated by more than just the issues -- or at least one of them will be.

After Pence's close proximity to others who have tested positive for COVID-19, the Harris campaign requested plexiglass barriers be used at the debate and the commission agreed -- but the Pence campaign said Tuesday that they never agreed to a plexiglass partition.

A senior administration official in Pence's office told ABC News Tuesday that the CPD decided to publicize the new safety protocols before any formal agreement was made and that the moderator and the Harris campaign can do as they want, "but we do not."

The official said Center for Disease Control and Prevention guidelines recommend plexiglass whenever 6 feet of separation isn't possible, but noted the candidates will be 12-feet apart on stage. The comment fell in line with Pence's chief of staff Marc Short who told The Washington Post Tuesday that plexiglass is "not needed."

Pence's communications director, Katie Miller, who tested positive for COVID-19 in May, also responded to the request in a statement to Axios earlier this week saying, "If Sen. Harris wants to use a fortress around herself, have at it."

Following news that Miller's husband, senior Trump aide Stephen Miller, tested positive for the coronavirus, she reportedly left Utah and a spokesperson declined to comment if Pence would agree to plexiglass.

-ABC News Justin Gomez, Averi Harper and Ben Gittleson