By Koen Swinkels, on Medium, a database and preliminary interpretation subject to various caveats. The preliminary suggested interpretation is as follows:

• 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