Eight-to-ten-week-old female K18-hACE2 transgenic mice received 200 μg (about 10 mg kg−1) of the indicated mAb treatment or isotype control by intraperitoneal injection one day after intranasal inoculation with 103 FFU of Wash-B.1.351 SARS-CoV-2. At six days after infection, mice were killed and lungs fixed for sectioning before staining with haematoxylin and eosin. A lung section from a naive, uninfected mouse is shown (top panels) as a reference control. Images show low (left panels for each treatment) and high (right panels for each treatment; boxed region from left) resolution. Scale bars, 100 μm. Representative images from n = 3 mice per group.