Table 2.

Sex differences in immunological responses. The occurrence of autoimmune diseases is significantly higher in women than in men (up to 9:1). Some clinical aspects, mainly associated with pregnancy, and some biological features are reported. As concerns infectious diseases only some examples have been provided. Of note, COVID-19 severity and lethality are significantly higher in men.

Sex and the Immune System
		Occurrence	Clinical Aspects	Biological Features
A U T O I M M U N E D I S O R D E R S		-F > M -~85% of cases involve women [69]
	Systemic Lupus Erythematosus	-F > M -Higher risk in women using contraceptive pills [72]	Elliptical course of manifestation in females: Heightened during pregnancy [71]
	Multiple Sclerosis		Elliptical course of manifestation in females -Diminutive manifestation symptoms during pregnancy [69]	Protective role of oestrogens, progesterone and prolactin on the central nervous system [73]
	Rheumatoid Arthritis		Elliptical course of manifestation in females -Diminutive manifestation symptoms during pregnancy [69] -Aggravation after the first trimester after birth [74]	Lower levels of oestrogens, progesterone and humoral immune responses and higher levels of TNF-α and IFN-γ [74]
I N F E C T I O U S D I S E A S E S	Urinary tract infections	F > M [76]	Severity M > F [76]
	Influenza A	F > M [78]	More severe course in pregnant women [77]
	HIV	F > M [79]	Milder progression in women [77]	Severity M > F [77]
	HCV	M > F [80]	Milder progression in women [77]	Higher intensity and prevalence in males [77]
	COVID-19	M > F -Not significant differences (Pooled prevalence 55.00 vs. 45.00) [81]	Severity M > F [82] -Comparing premenopausal women and men of the same age [83] -Mortality associated with testosterone [88] -Higher propensity of hospitalization in men with androgenetic alopecia [90]	-Protective role of oestrogens [83] -Bifold features of testosterone [89,92]