ACE2 and Recurrent upper respiratory tract infections: Although there have been reports of less COVID-19 infection in children, there is a lack of evidence that ACE2 changes with age.37 A possible hypothesis is that children are less susceptible to COVID-19 infection due to cross-protective antibodies from multiple upper respiratory tract infections and that their lower respiratory tracts have less ACE2.49 Limited studies and data in children are available, and conclusive evidence to support postulations that children are less likely to be adversely affected by SARS-CoV-2 infection is lacking.