Although the link between e-cigarette use and SARS-CoV-2 infection is not yet fully understood, emerging evidence suggests that nicotine alone induces ACE2 upregulation in human broncho-epithelial cells [54], indicating that e-cigarettes high in nicotine may increase the risk of SARS-CoV-2 infection and COVID-19 [55,56,57]. This evidence concerns the gene ACE2 and COVID-19.