Pence's team insisted they were not medically necessary, an objection that came as Trump returned to the White House.
The Trump campaign is trying to move past the virus despite the President's own diagnosis.
Other reminders that these are not normal times for a vice-presidential debate: 20 chairs for guests are spaced roughly 1.8m apart in the debate hall, a performing arts centre on the University of Utah campus.
Additional guests will be seated in traditional theater seats, though they will have to sit spaced apart.
Everyone will be required to wear a mask.
Even the network TV cameras have plexiglass wrapping on the sides and back.
But the moderator, Susan Page of USA Today, does not.
The existence of barriers between Harris and Pence — but not between the candidates and Page — serves as a visual cue from Democrats that sharing the stage with Pence is the primary concern.
Both Harris and Pence tested negative for the virus yesterday, their respective teams said. A number of members of the Trump Administration are continuing to test positive.
- AP