Figure 1.
Pathogenicity of Omicron BA.1 and BA.2 in Syrian hamsters inoculated intranasally with BA.1 (n = 7), BA.2 (n = 5), or D614G (n= 8). A, Weight changes, shown as means with standard deviations. B, Infectious viral load and viral RNA detected in nasal wash samples on days 2 and 4 after inoculation. Abbreviation: TCID50, median tissue culture infective dose. C, Infectious viral load detected in oral swab samples from inoculated donors on days 2 and 4 after inoculation. D, Infectious viral load detected in the nasal turbinate and lungs of inoculated donors on day 4 after inoculation. A, B, Kruskal-Wallis test and Dunn multiple comparisons were performed to compare weight changes and viral loads of BA.1-, BA.2-, and D614G-inoculated hamsters at each time point. C, D, Mann-Whitney test was performed to compare viral loads of BA.1- and BA.2-inoculated hamsters. Spearman rank correlation coefficient analysis (right) was performed to evaluate the correlation between infectious virus load in oral swab (x-axis) and nasal wash (y-axis) samples. Experiments were independently performed 2–3 times. Dashed lines represent limits of detection.