Moreover, younger age, chronic comorbid conditions, morbid obesity, high-dose steroid use, hematopoietic stem cell therapy, lower levels of CD4+T specific cells and a lack of early antiviral therapy were also regarded as independent risk factors for severe disease, according to prior reports (Viasus et al., 2011; Chemaly et al., 2012; Li and Cao, 2017). This evidence concerns the gene CD4 and morbid obesity.