Antibiotics can be effective against secondary infections, i.e., when someone’s lungs get junked up with mucus due to viral infection, a secondary bacterial infection often develops. Antibiotics can and do treat those secondary bacterial infections. I
Viruses are inflammatory by itself and thus secondary infection is possible it is not the biggest issue unless we are talking about HIV. Treating secondary infection is not of much help when the primary one is untouched. Not to mention antibiotics are weakening the immune system enabling the virus in the first place.