I doubt a significant amount leached, but surface contact alone would be a potent antiseptic.
“Brasses demonstrate bactericidal efficacies, but within a somewhat longer time frame than pure copper. All nine brasses tested were almost completely bactericidal (over 99.9% kill rate) at 20°C (68°F) within 60–270 minutes.”
Colloidal silver also has a good reputation against bacteria. Many years ago when I was a child, when I was sick my doctor used to dip something like a fat Q tip into a product called Argerol, have me lay down and put them in my nostrils for 10 minutes. I think this was to keep me from getting a strep throat or an ear infection.