It seems like you could get away with it covering only the things that Penoxycycline doesn't. While it's not as convenient, having two drugs working on concert would feel more plausible to me than a miracle cure. In fact, if it was a focused anti-parasite/mechanite drug, then that would make a lot of sense, thematically. Then the remaining flu and infections could be covered by an advanced Penoxycycline variant, perhaps named Veroxycycline? (My cursory dictionary research indicates that "pen-" means "almost", whereas "ver-" means "true". Probably a very rough attempt though...) Then the cost could be split between the upgrade recipe and Nanitride. I don't know why complicating things like this appeals to me... But that's how my brain works.