Figure 2.

In vivo efficacy of ensitrelvir compared with that of nirmatrelvir against Omicron BA.2 in a hamster infection model. Syrian hamsters were intranasally infected with 1.0 × 10⁴ TCID₅₀ of SARS-CoV-2 Omicron BA.2. The hamsters were treated twice a day at an 8 h/16 h interval for 5 days starting 1 day p.i. with various doses of oral ensitrelvir (ETV), subcutaneous nirmatrelvir (NTV) or vehicle (0.5% MC solution). Hamsters were monitored daily. (a) Body-weight values are presented as a percentage of initial body weight through to Day 14 p.i. The graph bars represent the mean ± SD. n = 4/infected group; n = 3/non-infected group. (b) Hamster lungs (lower airway) and nasal turbinates (upper airway) were harvested and prepared 2 and 4 days p.i. Viral titres were determined using TCID₅₀ assays. Each point represents the mean ± SD of n = 6–8/group. The dashed line represents the LLOQ of 1.80 log₁₀ TCID₅₀/mL. P values were calculated using Tukey’s test. **P < 0.01 versus vehicle; ***P < 0.001 versus vehicle; ^###P < 0.01 versus 12.5 mg/kg ETV; ^§P < 0.05 versus 250 mg/kg NTV; †P < 0.05 versus 750/250 mg/kg NTV; ††P<0.01 versus 750/250 mg/kg NTV. This figure appears in colour in the online version of JAC and in black and white in the print version of JAC.