Medical researchers believe they have uncovered why COVID-19 may be less common in kids than in adults.

According to findings published in The Journal of the American Medical Association, the virus that causes COVID-19 uses a receptor known as ACE2, found on the surface of certain cells in the human body, to enter its victims.

Mount Sinai researchers have found that children have lower levels of ACE2 gene expression than adults, which may explain children’s lower risk of COVID-19 infection and mortality.

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Gene expression is a measure of how much a gene is transcribed.

The results, published in the journal on Wednesday, May 20, may point to a potential biomarker of susceptibility to the virus, known as SARS-CoV-2.

The analysis examined nasal passages epithelium from Mount Sinai Health System patients ages 4 to 60.

The researchers found ACE2 gene expression in nasal epithelium was age-dependent, lowest in younger children and increasing with age into adulthood.

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