To determine whether antiviral resistance is present, you can go to the hospital for a viral load test or a viral sequence analysis. 1. Quantitative viral testing: Quantitative viral testing can determine the degree of infection by checking the amount of virus in a sample of body fluid. When antiviral resistance testing is performed, changes in viral load can also indicate whether or not the currently used drugs are effective or whether viral resistance exists. If the viral load does not decrease or increases, antiviral resistance is suspected. 2. Sequence analysis: Viral sequence analysis refers to the analysis of the viral gene sequences of a virus, which can be compared with known drug resistance genes to determine whether the virus currently being tested has a specific drug resistance or whether the drug is effective. Antiviral resistance needs to be suspected when sequence analysis reveals the presence of drug-resistant fragments or similar genes. When performing antiviral resistance testing, you can choose the appropriate test method under the guidance of your doctor.