How Covid Kills Some People But Not Others – If you want to verify my credentials, feel free to do so on this website, from the American Board of Internal Medicine. Here you can see that I am board certified in all of my specialties.
This virus, we know, is mainly transmitted by respiratory droplets, and through contact, by getting into our mucosa, like our mouth, nose, and eyes. Although less common, it also can be transmitted through aerosol, meaning airborne. Most likely, when you have people in an enclosed space, such as an elevator, someone sneezes or coughs without covering their mouths, and someone else can inhale it in.
This virus attaches to cells in our body by this ACE2 receptor. This ACE2 receptor is only located on specific cells in our body. It’s on our tongue, in our nose, back of the throat, and in our lungs.
How Covid Kills Some People But Not Others
Specifically, within the lungs, it’s only located on our type II alveolar cells.
What’s that, you ask?
Let’s take a closer look at our lungs.
Ok, we know that ARDS develops in about 4 to 5% of COVID patients. And of all the people who get COVID, the mortality rate is around 1 to 2%. So why do some COVID patients get ARDS, and why do some die?
There are different reasons, and let’s talk about them. It could be one of these reasons, but more likely, it’s a combination of these reasons. So here we go.
1) The virus only gains entry into our cells that express the ACE2 receptor. They are located on multiple sites. Besides being in the lung, they’re in your mouth, nose, throat, stomach, small intestine, colon, skin, lymph nodes, thymus, bone marrow, spleen, liver, kidney, brain, and testes.
2) It makes sense that if the virus only gets into your mouth or nose or throat, but not the lungs, that it would cause only cold-like symptoms. But if the virus gets all the way down into the alveoli of your lungs, that’s what’s going to cause ARDS.
And by the way, the ACE2 receptors in your gut probably explain why some patients get nausea, vomiting, and diarrhea.
3) The amount of virus that you get into your body likely determines how sick you get. This is what we call the viral load.
4) The inflammatory reaction with COVID is highly complicated, with many different proteins and hormones, and interleukins at play. But there are several known genetic polymorphisms of these proteins that likely make some people more prone to getting worse illness than others. A genetic polymorphism means a variation on a particular gene. For example, there are genetic polymorphisms for the ACE gene, as well as IL-6. A lot of it comes down to our genes. And sex.
5) Because the 5th reason has to do with estrogen. Estrogen is known to inhibit the effects of IL-6, which plays a massive role in this cytokine storm. This might explain why women overall have the less severe disease compared to men.
6) And the 6th reason by being because of people who are already taking certain medications. For those already on an ACEI such as lisinopril, or an ARB such as losartan, or telmisartan, or candesartan, or irbesartan. Or people who take hydroxychloroquine for lupus or rheumatoid disease. Or people who take tocilizumab and IL-6 receptor inhibitors. Are these patients less prone to getting severe illnesses? My guess is yes.
And now, I know there is a theory circulating about how the virus might be attacking our hemoglobin. The theory is based on this non-peer-reviewed study that showed the virus, in a test tube, not in our body or an animal’s body, but in a test, tube COULD attack hemoglobin, which is in our blood. Precisely it is speculated that it might strike the Beta 1 chain of Hemoglobin in our blood.
Even if it could attach to the beta1 chain of hemoglobin, I can tell you that is not how the virus is causing disease. We know this because
1) We know it binds to the ACE2 receptor and gains entry into our cells that way.
2) We see with our own eyes the destruction that it causes to the alveoli.
3) We know that the COVID patients have a low P: F ratio, which means that the reason for low oxygen is because the lungs reduced the ability to move oxygen from the air to your bloodstream. People with low oxygen levels due to an issue with hemoglobin, for example, with methemoglobinemia, have an average P: F ratio. Patients with methemoglobinemia have a low oxygen saturation but an average P: F ratio. In COVID ARDS, these patients have low P: F ratios.
4) RBC does not have ACE2 receptors; the virus is not able to invade RBC.
5) Hb usually does not exist outside of RBC, except when the RBC bursts, which we call hemolysis. In COVID patients, we do not see hemolysis. Therefore there is no way the virus can attack hemoglobin, except for perhaps, a very tiny bit of hemoglobin that can exist in the alveoli due to alveolar damage from ARDS.
Doctor Mike Hansen, MD
Internal Medicine | Pulmonary Disease | Critical Care Medicine
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