I'm taking my euphonium to a professional for cleaning and general maintenance. Last time I've done this was 3 years ago. When I went to pick it up, he blew into the instrument as part of a demo (at least, IIRC?). AFAIK, they may do that as they're doing their work?
As a precaution, what can I do to prevent infection? He already cleaned the instrument. Should I request that he not blow into after all is done? Is there an amount of time I should wait before practicing on it?
Studies I've found show that COVID-19 can live on metal surfaces for 5 days. However, that's presumably with the surface being exposed to air, as opposed to confined in metal tubings and casings of a brass instrument like a euphonium/baritone horn.