If something refers to COdA, it means the disease that mutated to become COdA way back in January. In your case red. So a card of the "COdA color" would be a red card, regardless of whether or not it's a Faded city. San Francisco may have Faded, but it's still a blue city, and your blue disease is not COdA.
If something refers to a Faded City, then it means a city that has Faded, regardless of color. If something tells you to discard a City Card that matches a Faded City, for instance, then you could discard San Francisco or Delhi.
If something refers to a Faded City, then it means a city that has Faded, regardless of color. If something tells you to discard a City Card that matches a Faded City, for instance, then you could discard San Francisco or Delhi.