Why men and women respond to COVID-19 coronavirus differently? (2)

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You are renowned immunologist. Sex differences in immune response to infections is one of your interests. Coronavirus is killing twice more men than women. COVID-19 also infects more men than women. Men are hospitalized more frequently with coronavirus disease. It’s true in New York. It’s certainly true in China. Why men and women respond differently to coronavirus infection? I think we have to step back here. We have to appreciate that what we call the immunophenotype. Immune characteristics are quite distinct when one looks at men and women. Women tend to have a more robust immune response when challenged with different pathogens. Those pathogens could be bacteria. They could be parasites. Or for the purpose of this conversation pathogens are viruses (COVID-19). If you just sample the blood of men and women, you’ll see that the numbers of different immune cells are different in men and women. There is a difference in absolute numbers of immune cells in men and women. Women have more T cells. These T cells are really important for clearance of viruses. When you think about it. Women, females carry the fetus. So they need to have a more robust immune response just by virtue of their reproductive capacity. So yes, when we look at a number of virus infections, we will see that women tended to have a more robust immune response. Women clear the virus quicker. Women have less severe virus disease. This apparently seems to be the scenario with COVID-19 coronavirus. How much in the COVID-19 coronavirus patients the environment versus genetics plays a role? How it affects the differences in the severity of COVID-19 coronavirus infections? It’s not just genetics. Let me be clear. So there are female hormones, which are really important for activating immune responses. So you’ll find that postmenopausal women might not have a strong immune response to the COVID-19 coronavirus. Strong immune response is in the pre-menopausal or post-pubertal women. So yes it’s the genetics. It’s the X chromosome, which encodes many genes associated with an immune response. Plus it’s the female hormone. So let’s just make that absolutely clear. All those female features offer an advantage to the COVID-19 coronavirus response in females. There are also gender influences that people aren’t even talking about right now. Your gender will influence, for example, your exposure to the virus. How often you’re outside the home? Who you interact with? Sex difference may have an impact in various jurisdictions on why women are less likely to be infected than men with COVID-19 coronavirus. If women stay at home more, for example, they won’t be out in the public. Women won’t be exposed to COVID-19 coronavirus. There are many factors which might influence risks. This is what we’re seeing right now. It perhaps a little bit premature to put your finger on one specific scenario why women do better in COVID-19 coronavirus. Whether it’s the immune response, a very specific T cell response, whether it’s the antibody response to COVID-19 coronavirus. At this stage I think it’s a little premature to say what specifically gives women advantage in COVID-19 coronavirus infection risks.