Why is it generally harder to achieve selective toxicity for antiviral drugs than for antibacterial drugs?

Antibiotics face less immune interference since bacterial infections are extracellular, while antiviral drugs cannot be delivered systemically due to immediate neutralization by antibodies.

Viruses replicate inside host cells and use many host enzymes and pathways, so viral-specific targets are fewer and often similar to host components.

Antiviral compounds are rapidly metabolized by the liver more than antibiotics, which makes maintaining selective levels in tissues impossible with current pharmacology.

Because viruses are larger than bacteria and physically shield their proteins from drugs, making it more difficult for small molecules to reach viral enzymes.