STAT1 and obesity due to melanocortin 4 receptor deficiency: Other modified models for obesity (e.g., ob/ob and high-fat diet-induced obesity mice), diabetes (e.g., STZ-treated and NOD mice), and immune deficiency/impairment (e.g., SCID and STAT1-knockout mice) might be more easily available to analyze the progression of the severe status of SARS-CoV-2 infection (Croy et al., 2007; Cleary et al., 2020; Payab et al., 2021).