SARS-CoV-2 causes a wide range of clinical symptoms, including the potentially fatal acute respiratory distress syndrome (ARDS). The study was published Aug. 1 in the open access journal PLOS Biology Kirsty Short of the University of Queensland, Queensland, Australia, and her colleagues suggest that the nasal epithelium (the lining of the nose) of children inhibits infection and replication of the parent strain of SARS-CoV-2 and the Delta variant, but not the Omicron variant.
Children have lower rates of infection with COVID-19 and milder symptoms than adults. However, the factors underlying this apparent pediatric resistance to COVID-19 infections are unknown. To better understand the lower infection and replication of inherited SARS-CoV-2 in children, researchers obtained samples of primary nasal epithelial cells (NEC) from twenty-three healthy children aged 2-11 years and fifteen healthy adults aged 19-66 years in Australia. They exposed cells from adults and children to SARS-CoV-2 and then observed the kinetics of infection and antiviral responses in children compared to adults.
The researchers found that the ancestral SARS-CoV-2 replicated less efficiently and was associated with an increased antiviral response in the children’s nasal epithelial cells. This lower viral replication rate was also observed with the Delta variant, but not with the latest Omicron variant. However, the study had several limitations, including a small sample size, so future clinical trials are needed to confirm these preliminary findings in a larger population and to determine the role of other factors, such as antibodies, in protecting children from SARS-CoV-2 infection. Furthermore, pediatric protection against new variants has yet to be quantified.
According to the authors, “we have provided the first experimental evidence that the pediatric nasal epithelium may play an important role in reducing children’s susceptibility to SARS-CoV-2. The data strongly suggest that the nasal epithelium in children is different and that this may give children a certain level of protection against hereditary SARS-CoV-2”.
Short adds, “We use pediatric and adult nasal epithelial cells to show that ancestral SARS-CoV-2 and Delta, but not Omicron, replicate less efficiently in pediatric nasal epithelial cells.”
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