Fig. 7. Effects of intranasal challenge with the Omicron VoC on tracheal tissue in vaccinated and control hamsters at days 3 and 5 post challenge.

H&E staining (1^st and 3^rd column) and IHC staining against N protein (brown, 2^nd and 4^th column), 20x, scale bar = 50 µm. N = 4. In animals that received an AZD1222 vaccination, minimal pathology in one animal and rare immunoreactivity in 3/4 was observed on day 3. No pathology nor antigen staining in animals on day 5. In animals that received an AZD2816 vaccination, no pathology or antigen staining was observed on day 3 or day 5. Control animals show moderate tracheitis on day 3 with moderate immunoreactivity. 2/4 animals had minimal pathology on day 5 and rare immunoreactivity.