danensis, while there may be links between some "nursery rhymes" and events in history, that's insufficient evidence for linking a particular rhyme to a particular event. Linguists, etymologists, and folklorists generally refuse to accept the link between "plague" or "Black Death" or any other particular event, eipdemiological or otherwise, and the "rind around the rosy" rhyme. It is a "folk etymology" unattested by hard evidence. You can still believe in it if you like, of course, but you're engagin in an act of faith, not science.