I prefer Iris Amelia/Emilia over Francesca, other similar feeling names you could consider:
Iris Antonia
Iris Julia
Iris Lucia
Iris Claudia
Iris Celia
Iris Helena
Iris Louisa
Iris Lydia
Iris doesnt sound anything like virus in my accent, so I wouldn't make the connection? As for the "old fashioned" thing - I know someone who has Iris as a middle name and was bit embarassed about it when we were young (about 30 years ago!) as it was too "grannyish" then, but she loves it now that there's more kids about with the name. I personally quite like it as it reminds me of both the goddess and the flower.