Pediatric nasal epithelial cells are less permissive to SARS-CoV-2 replication compared to adult cells

Zhu, Yanshan; Chew, Keng Yih; Karawita, Anjana C.; Yamamoto, Ayaho; Labzin, Larisa L.; Yarlagadda, Tejasri; Khromykh, Alexander A.; Stocks, Claudia J.; Xia, Yao; Kollmann, Tobias R.; Martino, David; Kicic, Anthony; Joensuu, Merja; Meunier, Frédéric A.; Balistreri, Giuseppe; Bielefeldt-Ohmann, Helle; Bowen, Asha C.; Sly, Peter D.; Spann, Kirsten M.; Short, Kirsty R.

Children typically experience more mild symptoms of COVID-19 when compared to adults. There is a strong body of evidence that children are also be less susceptible to SARS-CoV-2 infection with the original Wuhan isolate. The reasons for reduced SARS-CoV-2 symptoms and infection in children remain unclear and may be influenced by a multitude of factors, including differences in target cell susceptibility and innate immune responses. Here, we use primary nasal epithelial cells from children and adults, differentiated at an air-liquid interface to show that SARS-CoV-2 (both the Wuhan isolate and the more recent Alpha variant) replicates to significantly lower titers in the nasal epithelial cells of children compared to those of adults. This was associated with a heightened antiviral response to SARS-CoV-2 in the nasal epithelial cells of children. Importantly, influenza virus, a virus whose transmission is frequently associated with pediatric infections, replicated in both adult and paediatric nasal epithelial cells to comparable titres. Taken together, these data show that the nasal epithelium of children supports lower infection and replication of SARS-CoV-2 than the adult nasal epithelium.