[cloudmountain]

I was present twice when a Communion host was dropped, AFTER it was consecrated and became the Body, Blood, Soul and Divinity of Jesus. [I'm old and have been to Mass umpteen zillion times...daily Mass, in fact, since 1980.]

In each case the priest takes the dropped host and puts it aside for the moment. AFTER Mass the priest does something with it. There IS a ritual, purpose and method for dealing with these accidents.
There HAD to be, of course, since dropping things is what we humans do.

I don't know what he does with it. He may consume it. I knew the answer eons ago but have FORGOTTEN!

[defconw]

You're correct he would consume it OR he could dilute it and let it down into the piscina. (A pipe that goes directly into the ground).