Just a personal observation: when I first moved into a giant-open plan office in 2015 in a big German company, I got significantly more sick. It was horror. Also, bathrooms were unusually crowded, probably helping spread diseases. Since then, it seems my body got a bit used to it and I am sick less often. But is is still more than the times before.
What might also increase days that people are not there: at least in our office we actively encourage people not to come back from sickness soon. We urge them to stay at home to avoid spreading disease further. While I personally might come back to a single office after 2-3 days, as I can't that easily infect other people in my private office, I stay away for a week more often now.