Figure 3. Vaccine-mediated protection against lung pathology in 129S2 mice.

Seven to nine-week-old female 129S2 mice were immunized, boosted with 0.25 μg of mRNA vaccines (control, mRNA-1273, mRNA-1273.351, or mRNA-1273.211), and challenged with B.1.351 as described in Figure 2. Hematoxylin and eosin staining of lung sections harvested at 4 dpi or from a mock-infected animal. Images show low- (top; scale bars, 1 mm) and high-power (bottom; scale bars, 50 μm). Representative images from n = 2 per group.