Decreases of SARS-CoV-2 antigen titers in the nasopharyngeal swabs after switching from remdesivir (RDV) to ensitrelvir (ESV) in Case 1 (A) and Case 2 (B). Viral antigen titers are presented using log scales, and statistical analysis were performed by geometric and Kraskal-Wallis analysis judged by *p<0.05 as the significant. Statistical significant viral reduction was found in Case 1 (**p<0.01), and tendency in the Case 2. Dotted lines mean the regular threshold (excluding hematological patients) of the viral antigen titer in our hospital (100=10² IU).