A review of studies on copper surfaces found no effect from oxidation on the effectiveness of the anti microbial property. Will look for link when not on phone.
https://www.sciencedirect.com/science/article/pii/S0010938X17313963
https://aem.asm.org/content/77/5/1541
https://web.archive.org/web/20101211230503/http://www.antimicrobialcopper.com/media/69850/infectious_disease.pdf
A review of studies on copper surfaces found no effect from oxidation on the effectiveness of the anti microbial property. Will look for link when not on phone.
https://www.sciencedirect.com/science/article/pii/S0010938X17313963
https://aem.asm.org/content/77/5/1541
https://web.archive.org/web/20101211230503/http://www.antimicrobialcopper.com/media/69850/infectious_disease.pdf