Table 1.

Studies concerning co-morbidities of obesity and coronavirus infections

Reference	Study design	Co-morbidity associated with obesity	Relationship with the worsening prognostic of coronavirus infections
Yang et al.(164)	Human study, retrospective analysis	Hyperglycaemia and hypertension	Patients admitted to Beijing hospitals diagnosed with SARS showed increased risk of severe hypoxia and death risk, due to hyperglycaemia and ketosis effects
Kulcsar et al.(105)	Mouse model	Type 2 diabetes	Mice with diabetes showed increased expression of IL-17a after infection by MERS-CoV
Al Heialy et al.(98)	Re-analysis of publicly available transcriptomic data and mouse model	Diabetes	Human pulmonary epithelial cells infected with SARS-CoV-2 presented positive regulation of the suppressor of the SOC3 gene, which regulates inflammation and inhibits leptin signalling, favouring viral replication. A mouse model of diet-induced obesity showed increased ACE2 expression in the lungs by the suppression of genes that encode SREBP1
Zheng et al.(118)	Human case–control study	MAFLD	A multi-centre study involving 214 patients with laboratory-confirmed COVID-19 aged between 18 and 75 years of three hospitals in the city of Wenzhou (China) to investigate the association between MAFLD and COVID-19 severity. Data showed that the presence of obesity in patients with MAFLD increased six-fold the risk for severe COVID-19

SARS, severe acute respiratory syndrome; MERS-CoV, Middle East respiratory syndrome coronavirus; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SOC3, suppressor of cytokine signalling 3; ACE2, angiotensin-converting enzyme 2; SREBP1, sterol regulatory element-binding protein 1; MAFLD, metabolic associated fatty liver disease; COVID-19, coronavirus disease 2019.