The lack of manifest clinical symptomatology and/or severe forms of COVID-19 in children and adolescents below the age of 15 mentioned above could be related to the presence of an immature form of ACE2 in this population, or lower expression levels of the enzyme, as recently documented in a study of 305 individuals aged 4–60 showing a clearly lower ACE2 gene expression in children <10 years old (Bunyavanich et al., 2020). Here, ACE2 is linked to COVID-19.