Nasal ACE2 Levels and COVID-19 in Children

Abstract

Coronavirus disease 2019 (COVID-19) has disproportionately affected certain vulnerable populations. Studies noted higher rates of certain comorbidities such as hypertension, diabetes mellitus, and chronic obstructive pulmonary disease in patients infected with COVID-19 with severe disease. 1 Additionally, areas with more racial/ethnic minorities and higher rates of poverty have been shown to have higher rates of COVID-19 hospitalization and death. 2 After adjustment for comorbidities, age has been independently associated with increased mortality due to COVID-19. 3 However, limited attention has been given to children, who appear to have lower risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and mortality.In this issue of JAMA, Bunyavanich et al 4 identify a possible factor that may be related to lower rates of SARS-CoV-2 infection in children. The authors evaluated gene expression in nasal epithelial samples collected as part of a study involving patients with asthma from 2015 to 2018. The nasal epithelium is one of the first sites of infection with SARS-CoV-2, and the investigators probed for the expression of the cell surface enzyme angiotensin-converting enzyme 2 (ACE2), which has been proven to bind to SARS-CoV-2 spike protein and promote internalization of the virus into human cells. 5 Among a cohort of 305 patients aged 4 to 60 years, older children (10-17 years old; n = 185), young adults (18-24 years old; n = 46), and adults (≥25 years old; n = 29) all had higher expression of ACE2 in the nasal epithelium compared with younger children (4-9 years old; n = 45), and ACE2 expression was higher with each subsequent age group after adjusting for sex and asthma.Numerous studies have highlighted the low rates of SARS-CoV-2 infection in children compared with adults. Children have been shown to have fewer and less severe symptoms compared with adults. 6,7 This leads to the question of whether low rates of SARS-CoV-2 infection in children are due to low rates of testing in children, or if children are less susceptible to infection. An evaluation of 1286 close contacts of index cases in China found that infection rates in children were comparable with or slightly higher than in younger adults (aged 30-49 years) but were significantly lower than in older patients (aged ≥60 years). 8 This finding suggests that children seem to have similar rates of becoming infected compared with middle-aged adults following close contact with a person infected with SARS-CoV-2. In contrast, a targeted screening approach in Iceland found SARS-CoV-2 in 6.7% of children younger than 10 years old (n = 564) compared with in 13.7% of people aged 10 years or older (n = 8635). A population-wide screening approach not

Chest CT in COVID-19: What the Radiologist Needs to Know

“…ACE2 is highly expressed on the epithelial cells of the oral mucosa and lungs but also in the heart, blood vessels, intestine, kidney, bladder, and brain (7,9,10).TMPRSS2 is highly expressed with a broader distribution, suggesting that ACE2 rather than TMPRSS2 may be a limiting factor for viral entry at the initial infection stage (11). The nasal epithelium is one of the first sites of infection with SARS-CoV-2 (11,12). Interestingly, it was reported that ACE2 gene expression is lower in the nasal epithelium of children than that of adults, which may help explain why COVID-19 is less prevalent in children (13).…”

Early institutional head and neck oncologic and microvascular surgery practice patterns across the United States during the SARS‐CoV‐2 (COVID19) pandemic

“…This is of special concern to otolaryngologists, who are among the highest risk specialties for COVID‐19 exposure from nasal and mucosal procedures and examinations 3,4 . The highest concentration of viral particles is found in the nasopharynx and routine procedures performed by otolaryngologists can easily aerosolize viral particles and allow for airborne trasmission 5,6 .…”

Clinical and laboratory characteristics of SARS-CoV2-infected paediatric patients in Jordan: serial RT-PCR testing until discharge

“…It is not clear whether those with prolonged positive RT-PCR results had a more viable virus, and, conversely in those with a shorter duration of positive results, whether parts of the virus may have been no longer viable [29]. It has been demonstrated that angiotensin converting enzyme 2 (ACE2) receptors in the nasal epithelium of children under 10 years of age are expressed at lower levels than in older children [30,31]. This might explain earlier clearance of the virus and viral particles from the nose in the younger age group.…”