 A monoclonal drug is now being sold to help fight respiratory syncytial virus in babies, and antibodies purified from infected individuals are also used as a treatment for hepatitis B.

Antiviral resistance can be defined by a decreased susceptibility to a drug caused by changes in viral genotypes.In cases of antiviral resistance, drugs have either diminished or no effectiveness against their target virus.The issue inevitably remains a major obstacle to antiviral therapy as it has developed to almost all specific and effective antimicrobials, including antiviral agents.