I wouldn't say either are "easy". A new vaccine for the flu every year is more like finding a new lock combo solution for the same lock (recombinant DNA). Havi

I wouldn't say either are "easy". A new vaccine for the flu every year is more like finding a new lock combo solution for the same lock (recombinant DNA). Having to find a new antibiotic more like an entirely different door. Vaccines merely find a way to train our immune systems to tag the villain. Anti biotics have to actually find weaknesses and exploit a biochemical pathway that can be disrupted etc.