This makes me wonder how many of those additional absences in open plan offices are due to depression / introverts recoiling in horror rather than increased biological pathogen transmission.
That was my thought. When I worked in large open "bullpen" office I certainly did "take a sick day" from time to time just because I could not stand the thought of spending 8 hours in that environment on that day. I was never actually sick any more often than normal during that time.
It's definitely not just introverts either—me and a number of friends are not introverts per se but definitely take advantage of WFH whenever possible just to have some privacy and a break from the chaos.