Experimental design and SARS-CoV-2 RNA shedding. (A) Two dams and their respectively 6-month-old infants were inoculated intratracheally and intranasally with 2.5 × 106 PFU and 1.5 × 106 PFU of SARS-CoV-2 (WA strain), respectively. Nasal and pharyngeal swabs, bronchoalveolar lavage (BAL), blood, breast milk and rectal swabs were collected over time up to day 14 post-challenge. Additionally, lung radiographs were performed throughout the experiment. (B) Log10 viral RNA copies per mL are reported for nasal swabs, pharyngeal swabs, BAL supernatants and pellets, buccal swabs and rectal swabs over time for both the genomic (Orf1a gene) and subgenomic (N gene) viral RNA.