Nasopharyngeal Expression of Angiotensin-Converting Enzyme 2 (ACE2) and Transmembrane Serine Protease 2 (TMPRSS2) in Children Compared to Adults Within Family Clusters Exposed to COVID-19

There is accumulating evidence that the lower levels of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) in the nasal epithelium of children may be related to a lower incidence of COVID-19 compared to adults. However, no direct evidence is available to support this hypothesis. In this study, we compared the transcript levels of ACE2 and TMPRSS2 in nasopharyngeal swabs (n=207) from children and adult members within COVID-19-exposed families and assessed their association with SARS-CoV-2 infection status. The expression of both genes was higher in adults compared to the children (n=115 adults and 92 children, p