So why are men are 1.7 times more likely to die from the virus than women? One of the first explanations, researchers say, comes from basic biology. Women have two X chromosomes, men have one. X chromosomes are important because they are rich in genes that regulate immune response. While one of those X chromosomes in women is silenced, in some cases key genes from both X chromosomes can activate the innate immune system, the early alarm system that detects pathogens. Essentially, women have immune system reinforcements they can call upon early in infections that men, with their single X chromosomes, don't possess.
Sex hormones also play key roles in susceptibility to bad outcomes,
research has shown. In a mouse model of SARS-CoV infection, higher mortality in male mice was observed and attributed to the protective roles of the female sex hormone estrogen. The presence of estrogen can help suppress ACE 2, a receptor on the surface of many cells that is used by SARS-CoV-2 to enter cells. Conversely, the male hormone androgen appears to enhance the ability of the virus to infect cells. A study found that men undergoing androgen deprivation therapy for prostate cancer appear to be less susceptible to infection by the COVID-19 virus.