It is about time someone put this together, here are some summary conclusions:
- Nearly all SSEs in the database — more than 97% — took place indoors
- The great majority of SSEs happened during flu season in that location
- The vast majority took place in settings where people were essentially confined together, indoors, for a prolonged period (for example, nursing homes, prisons, cruise ships, worker housing)
- Processing plants where temperatures are kept very low (especially meat processing plants) seem particularly vulnerable to SSEs
Here is the full material by Koen Swinkels, via Balaji.