Why men and women suffer differently from Covid19?

You might have realised that not all people are affected by Covid19 disease in the same way. Some get more sick, others barely have any symptoms and unfortunately some even die from this awful disease. Many people are aware that older people suffer a lot more from the symptoms than younger ones. Also, people that were already sick with other diseases shows more symptoms when they are infected with the SARS-CoV-2. But did you know that there are also differences between men and women and how much this virus affects their health and even chances to survive the disease?
Even in previous coronavirus outbreaks with the SARS and the MERS virus, it looked similar: 22% of cases of infected men died from the SARS virus and 13% of infected women. Of the men that were infected with the MERS virus 52% died and 23 % of the women.
In the current SARS-CoV-2 outbreak, the numbers look very similar and they are supported by animal studies. So, researchers are trying to understand why this difference exist. Why are women more protected from this nasty virus than men?
Here, we will answer some of these questions to better understand the behaviour of this virus.
Let’s start with looking at how the SARS-CoV-2 virus enters our bodies. When we inhale this virus, it enters into our lungs where it will meet the lung cells. These lung cells have a so-called ACE2 receptor on their surface. This receptor works like a lock and the virus and its spike protein are the key to this lock.
Next, the protease TMPRSS2 cuts the spike protein so that it is tightly bound to the human cell. Now, the membrane of the human cell fuses with the membrane of the virus and completely envelopes the virus. Like this, the virus is taken up into the cell and the cell is infected.
Interestingly, the differences between the male and the female immune system start already here. Women have generally higher levels of the sex hormone estrogen in the body. This hormone decreases the amount of ACE2 receptors present on the lung cells. So, if there are fewer of these receptors on the lung cells, fewer viruses bind to them and thus fewer viruses enter and infect the cells.
On the other hand, the protease that cleaves the virus from the receptor, is activated by the male sex hormone androgen. So, in men more of the protease is present to help the virus enter the cell. This leads to more viruses infecting lung cells and causing disease.
But this is not the only influence that our sex hormones have on Covid19-disease severity. You might have heard of the so-called ‘cytokine-storm’ that happens in many Covid19 patients and can lead to death of the patient. This happens when the immune cells become hyperactivated and release larger amounts of the immune molecules called cytokines. These then activate more immune cells and altogether they lead to an inflammation of the lung cells.
The female sex hormone estrogen binds to special receptors of immune cells and activates them. Now more estrogen is produced and this increased amount of estrogen suppresses the release of proinflammatory cytokines. Like this, estrogen inhibits this cytokine storm and thus protects patients from tissue damage and this exaggerated immune response.
Another sex hormone that might impact disease severity is progesterone. This hormone has anti-viral effects, but so far its protecting effects were only shown for the influenza virus. Researchers are not sure yet whether it also protects from coronavirus infections.
In addition to the influence of sex hormones on the different outcomes of Covid19 disease, the immune systems of men and women work generally differently. First of all, many genes that are involved in the immune system are located on the X chromosome. Since women have two X chromosomes, they have generally more weapons available to fight incoming nasty pathogens than men.
Also, in the blood of women are generally more T and B cells present. These are the cells that find and fight incoming pathogens. So, women already have a lot more of these fighters. Plus, researchers found that men have more T cells that bind bacteria and protect from bacterial infections. On the contrary, women have more T cells that bind viral proteins and thus protect from viral infections. So, these “women-specific” T cells help fighting the incoming SARS-CoV-2 virus.
Lastly, the sex hormone estrogen helps B cells to become mature. This means they fully develop their fighting gear. Like this, estrogen also actively helps eliminate pathogens like the SARS-CoV-2.
Okay, thanks for listening until here. I hope you could learn a bit about the differences of how men and women struggle with and fight the nasty SARS-CoV-2 virus. If you have any more questions, feel free to contact us or drop your message in the comment box on the right.