The vomit could have vaporized into the closed off rooms and been either breathed in or cause virus to splash them by way of breeze or use of a air conditioner or heater. The intake of a unit could maybe draw virus in the ducts and all over everyone.
IF he’s got it, my vote goes to the vomit on the sidewalk as a source. Probably stepped in it on his way in/out of the apt.
vomit does not vaporize...
I’m thinking the helicopter hovering overhead taking the pictures probably didn’t help with containment of the fomites either.