Table 3.

Causal explaining variables between gender/sex and COVID-19 severity, classified into mediators and confounders. Mediators are the intermediate variables on the causal path from sensitive attribute to the outcome. A confounder is a variable with incoming arrows in the graph to both sensitive attribute and an outcome (a cause for both) and creates spurious non causal relationship between the two.

Variable and source	Class	Group	Comments
Hormones (Chiarella et al., 2021, Dana et al., 2020, Klein et al., 2020, Peckham et al., 2020, Traish and Morgentaler, 2021)	Mediator	Sex-related Bio Var	Male hormone testosterone is associated with increased vulnerability, whereas female hormones are believed to play a protecting role.
Immune response (Chiarella et al., 2021, Dana et al., 2020, Grzelak et al., 2020)	Mediator	Sex-related Bio Var	More protective antibodies are formed in women and they last longer.
Smoking and drinking (Bwire, 2020, Gebhard et al., 2020)	Mediator	Gender-related Lifestyle Var	Higher smoking and drinking rates among men induce lung injuries that affect COVID-19 vulnerability.
Stress (Gebhard et al., 2020)	Mediator	Gender-related Lifestyle Var	Men often are more exposed to stress at work.
Hazardous industry (Kabir et al., 2019, Silpasuwan et al., 2016)	Mediator	Gender-related Lifestyle Var	It is worth noting that in some Asian countries women constitute a majority of garment and textile sector workers that are exposed to unsafe work conditions and are reported to be hit by the pandemics more than men.
Health behaviour (De La Vega et al., 2020, Gebhard et al., 2020, Tadiri et al., 0000)	Confounder	Gender roles related Var	Women are more health -conscious and compliant with health recommendations
Exposure to pathogens (Wenham et al., 2020)	Confounder	Gender roles related Var	In traditional societies women stay at home, and therefore are less exposed to the virus.