Unless there's been some other code words for, or direct reference of, Covid-19, I'd say these color codes are a reference to that. I don't hear many local EMS calls that don't clarify that for the responding EMT's.
Actually there are large areas of the county where Monroe is the primary EMS now; more than "some". But yes, they do a lot of transfers and calls to places like nursing homes too (even in other ambulance companies' districts).
To add on, "Green" and "Red" for AMR are most certainly lights and sirens versus no lights and sirens, as others have stated. When Covid was more common in Rochester, I believe they used "Grey Response" for Covid positive patients, but I haven't heard the term since March or April.