Urban Density and Virus Spread

The following article notes how urban density is being blamed for pandemic virus spread:
https://www.politico.com/states/california/story/2020/03/27/california-saw-dense-housing-near-transit-as-its-future-what-now-1269263

But it also notes that less dense suburban areas have been hit as hard:


So what are the real factors that cause viruses to spread, whether through dense urban areas or less-dense suburban ones?

The answer lies in understanding why social-distancing isn't something that people do automatically when there's not a virus threat.

People who live in suburbs still drive to stores, schools, churches, and other places where pathogens are exchanged. They are not physically isolated just by living farther away from each other.

Public transit is going to be threatened by fear of contagion, but that also includes air-travel, so some innovations are going to be needed to reduce the threat of contagion in shared public areas like transit vehicles.

Trains used to have compartments as well as cars with row seating like airplanes, for example. We may see the development of buses whose passenger compartments are divided and all have doors opening from the outside so that riders can wave a chipcard opening an automatic door that doesn't require any touching, much like the sliding doors on retail stores.

Sprawl is really bad for the environment and climate, not to mention requiring expensive multilane roads/highways and parking lots that are an ugly waste of land. As such, it would be a step backward to react to pandemicphobia by abandoning progress toward car-free cities just because people might feel subjectively safer by driving farther away from the store after exposing themselves to the shared spaces there.