Antibiotics are not antivirals. Antibiotics kill bacteria, not viruses. Thus their help is limited to fighting off other infections, and this does have a modest effect on outcomes in the mod now. If you have another infected wound (that isn't a zombie virus infection), it'll heal slower and more painfully, both factors that reduce your odds of surviving the zombie virus.

I could see an argument for adding some generic (or HIV-specific) antivirals as loot drops, but right now it's still worth disinfecting the wound and taking antibiotics to prevent additional infections, and staying out of combat until the virus passes (or you do).