The study is “Sex Differences in Severity and Mortality Among Patients With COVID-19: Evidence from Pooled Literature Analysis and Insights from Integrated Bioinformatic Analysis” found in PDF format here.
“39 studies met inclusion criteria, representing 77932 patients, of which 41510 (53.3%) were males. Men were at a markedly increased risk of developing severe cases compared with women (OR = 1.63; 95% Cl = 1.28-2.06). Furthermore, the pooled odds ratio (OR) of mortality for male group compared with the female group indicated significant higher mortality rate for male (OR = 1.71; 95% CI = 1.51-1.93). Subgroup analyses suggested that in patients with average age > 50 yr, the male had significantly higher severity rate than female (OR = 1.94; 95% Cl = 1.16-3.26). However, in patients with average age < 50 yr, the male group only exhibited a marginally increased severity rate compared with the female group (OR = 1.45; 95% Cl = 1.07-1.96). Data from scRNA-seq suggest that men have a higher amount of ACE2-expressing pulmonary alveolar type II cells than women. Sex-based immunological differences exist, with cytokines associated with cytokine release syndrome preferentially expressed in men, and those associated with defense and recovery from viral infection preferentially expressed in women. ScRNA-seq data of the prostate and testis revealed that these two organs might be potential targets for SARS-CoV-2 infection in the male population. The expression of androgen receptor (AR) is positively correlated with ACE2, and there is evidence that AR may directly regulate the expression of ACE2."
The study found that, among adults over 50 years, who had the disease, men over 50 were almost twice as likely (94% more likely) to have a severe case than women over 50, and men over 50 were 71% more likely to die from the disease than women over 50.
For persons under 50 years, who had the disease, men were 45% more likely to have a severe case. Then for adults without regard to age, men were on average 63% more likely to have a severe case.
The reason given by the study is that women have fewer ACE2 receptors than men, especially in their lungs. More ACE2 receptors in men means more points of entry for the virus into cells and therefore a more severe case. In addition, the researchers believed that men were more likely to have a cytokine storm (over reaction of the immune system and excessive inflammation).
What are women’s odds as compared to men? Women over 50, as compared to men over 50, have a 48.4% lower risk of a severe case, and were 41.5% less likely to die of the disease. Then women under 50, as compared to men under 50, were 31% less likely to have a severe case. Finally, for adults without regard to age, women were 38.6% less likely to have a severe case.
UPDATE: Another study asserts that COVID-19 “mostly affects men, since immune genes are more expressed on the X chromosome.” So women have more genes governing the immune system as they have two X chromosomes, while men only have one X chromosome. Having a stronger immune system increases your chances of having a mild case and of surviving.