# Any new news on why this is severe/lethal to some, and not others? **URL:** \ **Category:** The Quarantine Zone\ **Tags:** covid-quarantine\ **Created:** [April 21, 2020, 4:22pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273 "2020-04-21T16:22:24Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [April 21, 2020, 4:22pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/1 "2020-04-21T16:22:24Z")
So about a week and a half ago, we found out that my dad indeed does have COVID-19. He’s essentially bedridden and lives in a nursing home in the Houston area that has several cases. He actually had to go to the hospital because he had a serious infection- while he was there, they tested him and it turned out that he had COVID-19 too. But that doesn’t seem to have really caused him any issues- the infection seems to have been the main thing making him acutely ill. What’s perplexing is that in all regards, he would seem to be a severe risk - 75 years old, Parkinsons, hypertension, diabetic, infection, etc… And yet, he somehow just shrugged off this virus like it wasn’t all that big of a deal. Meanwhile, I read about people in their thirties and younger catching this and ending up in the ICU and dying from it. Anyone know why this might be? This is the really perplexing part for me- we seem to have such a wide span of reactions to it- anything from asymptomatic to very quickly lethal, and nobody’s figured out why yet. ---
**Author:** ![madsircool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/madsircool/32/3432_2.png) [@madsircool](https://boards.straightdope.com/u/madsircool)\ **Post date:** [April 21, 2020, 4:28pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/2 "2020-04-21T16:28:12Z")
A Chinese study might give us a clue. > **[Coronavirus has mutated into at least 30 different strains new study finds](https://www.jpost.com/HEALTH-SCIENCE/Coronavirus-has-mutated-into-at-least-30-different-strains-new-study-finds-625333)** > > The study was carried out by Professor Li Lanjuan and colleagues from Zhejiang University in Hangzhou, China and published in a non-peer reviewed paper released on website medRxiv.org on Sunday. > [@](#): > > Li 's team infected cells with COVID-19 strains carrying different mutations, of which the most aggressive strains were found to generate as much as 270 times as much viral load as the weakest strains. The aggressive strains also killed the human cells the fastest. > > The results indicated "that the true diversity of the viral strains is still largely underappreciated,” Li wrote. > > The study could have future implications on the treatment of coronavirus, as several different strains have been found throughout the world. The United States, which has the world’s worst death toll at 42,897, and 799,515 overall cases, has been struck by different mutations. New York, which itself had the worst death rate in the US, and the eastern coast show a strain of coronavirus similar to that found in Europe, whereas the western US has shown similarities with strains found in China. ---
**Author:** ![MandaJo](https://avatars.discourse-cdn.com/v4/letter/m/ac91a4/32.png) [@MandaJo](https://boards.straightdope.com/u/MandaJo)\ **Post date:** [April 21, 2020, 5:03pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/3 "2020-04-21T17:03:41Z")
I cannot wait to read the book about this in 20 years. It seems important to me that across the board, it’s been dramatically less lethal for small children and signficantly less lethal for women. Men may be more likely to do things like smoke, so that may be noise, but the children thing is really dramatic. If we understood why, that might carry some important clues about why this is so much more lethal for some than for others. ---
**Author:** ![Lightlystarched](https://avatars.discourse-cdn.com/v4/letter/l/eb8c5e/32.png) [@Lightlystarched](https://boards.straightdope.com/u/Lightlystarched)\ **Post date:** [April 21, 2020, 5:18pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/4 "2020-04-21T17:18:37Z")
Early on there was some speculation about blood type, and certain types being more susceptible. I haven’t heard much about it since. I also recently saw an article about how the virus affects the blood and clotting factors were involved. Maybe people already prone to clotting issues are more at risk? It is fascinating reading the quickly evolving hypotheses and medication trials. Did you see the story about the common pet med (Ivermectin?) may help somewhat? I sure hope we can find a treatment avenue quickly. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 21, 2020, 5:28pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/5 "2020-04-21T17:28:08Z")
It is likely that there are specific genetic factors that indicate a predisposition to infection of the viruses’ preferred cell tropism, e.g. a certain configuration of proteins in the cell membrane or elsewhere in the machinery of the cell that make some people more inclined to severe infection. It has also been suggested in light of clear data that people with darker skin (not just “black” but other ethnicities with darker skin) have a higher incidence of serious COVID-19 presentations that Vitamin D, which is naturally produced by lighter skin people in greater quantity, may be a significant factor in the progression of the disease. While I have seen nothing definitive on that topic taking Vitamin D supplements–which are a general immune system booster anyway–is certainly an easy lifestyle modification to make with essentially no downside as long as you don’t exceed the [maximum recommended dosage](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/). Stranger ---
**Author:** ![DinoR](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dinor/32/2821_2.png) [@DinoR](https://boards.straightdope.com/u/DinoR)\ **Post date:** [April 21, 2020, 5:47pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/6 "2020-04-21T17:47:31Z")
I have not seen any follow up but one possible contributing factor is that there is a difference based on blood type. [Blood Type May Affect COVID-19 Risk: Study](https://www.webmd.com/lung/news/20200320/blood-type-may-affect-covid19-risk-study) > [@](#): > > A person’s blood type may affect their risk for COVID-19, the disease caused by the new coronavirus, researchers report. > > They analyzed blood samples from nearly 2,200 COVID-19 patients in China and tens of thousands of healthy people, and found those with A blood types had a significantly higher risk of COVID-19 while those with O blood types had a significantly lower risk, Newsweek reported. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 21, 2020, 5:57pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/7 "2020-04-21T17:57:48Z")
> [@DinoR](#): > > I have not seen any follow up but one possible contributing factor is that there is a difference based on blood type. > > [Blood Type May Affect COVID-19 Risk: Study](https://www.webmd.com/lung/news/20200320/blood-type-may-affect-covid19-risk-study) And what are the sample sizes for each group and corresponding statistical confidence intervals? In the Chinese mainland, approximately half of all people have a Group O blood type, while only about a quarter are Group A. In the United States and most European countries, the prevalence of those groups is roughly even. If anything about blood type were a discriminating factor I would actually expect it to be the Rhesus (Rh) factor for a number of reasons. Stranger ---
**Author:** ![ThelmaLou](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thelmalou/32/390_2.png) [@ThelmaLou](https://boards.straightdope.com/u/ThelmaLou)\ **Post date:** [April 21, 2020, 6:04pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/8 "2020-04-21T18:04:47Z")
> [@Stranger\_On\_A\_Train](#): > > It is likely that there are specific genetic factors that indicate a predisposition to infection of the viruses’ preferred cell tropism, e.g. a certain configuration of proteins in the cell membrane or elsewhere in the machinery of the cell that make some people more inclined to severe infection. … Possibly related issue. Apparently the Black Death of the 14th century created some genetic mutations that conferred immunity to HIV on modern descendants. > [@](#): > > …Seven hundred years later, we are still compelled by the story of the Black Death and the mysteries that surround it. How is it some people survived? Were they inherently immune? And how did a disease that killed so many seem to disappear? > > Scientist estimate the plague killed nearly half the population of Europe in the mid-1300s, but what happened to the other half? NIH researcher Stephen O’Brien’s work with AIDS identified a particular genetic mutation, Delta 32, that prevents both HIV and plague bacteria from entering human cells and causing infection–what geneticists cause a “positive mutation” because it confers survival benefits on those who carry it. > … > [Source](https://geneticliteracyproject.org/2014/04/04/black-plagues-quirky-genetics-700-years-later/) It seems to me that something like this could be at work. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 21, 2020, 7:25pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/9 "2020-04-21T19:25:32Z")
A prominent innate source of variation in immune response is the Major Histocompatibility Complex, aka Human Leukocyte Antigen - google **MHC haplotype** or **HLA haplotype**. MHC molecules sit on the surface of certain cells that process any proteins that they find and present them to the immune system for inspection. The MHC is the most genetically diverse region of the human genome, and it’s subject to active natural selection for diversity: it’s often an advantage to have _different_ MHC alleles to the majority around you, where the difference in itself is a virtue. Early in life, the adaptive immune system generates a huge random diversity of antibodies and receptors; then those that recognize “self” (molecules that are naturally present in the healthy human body) are deleted before the system goes active. If this were all that happened, it would be easy for pathogens to evade the adaptive immune system by evolving to superficially resemble the shape of molecules that are naturally present in the healthy body. But the MHC system is much smarter than this. It uses what amounts to encryption, where the encryption key that scrambles the shape of a protein is the MHC allele. Instead of just presenting proteins in their natural form to the receptors of the immune system, in Antigen-Presenting Cells any proteins that are found are systematically chopped up into samples that are bound to MHC molecules and presented for inspection on the outside of the cell. The shape that the immune system receptors “see” on the surface of these cells is not just the natural shape of the sampled protein, it is the shape when _complexed with_ the MHC molecule. So the effective shape is a function of both the shape of the sampled protein _and_ the shape of the MHC molecule. Since MHC molecules are highly diverse in the population, the same pathogen protein will be “encrypted” into a slightly different presented shape in the context of each different MHC allele. MHC polymorphism in the population creates a wide diversity of different encryption keys, making it vastly more difficult for a pathogen to evolve to always resemble “self” molecules. What is important is not how a protein looks in its raw state, but how it looks in its encrypted state when presented on the MHC molecule. It’s an inevitable consequence of this system that when a new pathogen arises, it will by chance form a more distinctive and obviously “non-self” shape when complexed with some MHC alleles than with others. So the immune system receptors in people with some MHC haplotypes may more easily detect its presence and eliminate it. We don’t yet know how important this is for COVID-19, but HLA haplotyping is routine (it’s the same thing as tissue typing for transplants), so I’m sure it will eventually be studied in detail. There are one or two preliminary publications looking at stats, but I’m not aware of anything based on actual testing of patients. > **[Individual genetic variation in immune system may affect severity of COVID-19...](https://neurosciencenews.com/coronavirus-genetics-immune-system-16199/)** > > Study reveals genetic variability in the immune system could affect susceptibility to coronavirus infection and govern the severity of the disease for those infected. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [April 21, 2020, 7:34pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/10 "2020-04-21T19:34:54Z")
There are always going to be exceptions. Your 30 year old friend that died was an exception to the norm. Your Dad surviving even though he had numerous risk categories was an exception. If you are older, and are predisposed with a vulnerable condition, there is a greater likelihood that you won’t survive it. > **[Coronavirus Pandemic (COVID-19)](https://ourworldindata.org/coronavirus#case-fatality-rate-of-covid-19-by-age)** > > Country-by-country data and research on the pandemic. Updated daily. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 21, 2020, 7:44pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/11 "2020-04-21T19:44:44Z")
> [@Omar\_Little](#): > > There are always going to be exceptions. Your 30 year old friend that died was an exception to the norm. Your Dad surviving even though he had numerous risk categories was an exception. Sure, but there’s a difference between an outcome being uncertain because we don’t yet understand the significance of all factors, and something being _truly_ random. This is surely the former case, and questions about factors other than just age and comorbidity are extremely important. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [April 21, 2020, 8:04pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/12 "2020-04-21T20:04:21Z")
> [@Riemann](#): > > Sure, but there’s a difference between an outcome being uncertain because we don’t yet understand the significance of all factors, and something being _truly_ random. This is surely the former case, and questions about factors other than just age and comorbidity are extremely important. What makes you think this is “surely” not random? ---
**Author:** ![MandaJo](https://avatars.discourse-cdn.com/v4/letter/m/ac91a4/32.png) [@MandaJo](https://boards.straightdope.com/u/MandaJo)\ **Post date:** [April 21, 2020, 8:07pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/13 "2020-04-21T20:07:52Z")
> [@scr4](#): > > What makes you think this is “surely” not random? Well, it seems worth looking into. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 21, 2020, 8:21pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/14 "2020-04-21T20:21:21Z")
> [@scr4](#): > > What makes you think this is “surely” not random? Because the factors that affect pathogen infectiousness and susceptibility are not random, just as incidence of cancer is not random but instead is based upon environmental exposure, genetic predisposition, et cetera. There may be different types of factors including things like nutrition and stress but the virus doesn’t just flip a coin to decide to attack; it exploits specific vulnerabilities to infect and reproduce. Stranger ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 21, 2020, 8:22pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/15 "2020-04-21T20:22:30Z")
> [@scr4](#): > > What makes you think this is “surely” not random? I’m not disputing that for a given individual, given our current state of knowledge, there may be a large _effectively_ random component in the outcome. That’s even true for diseases that we understand comparatively well, because biology is so complicated. But the distinction I’m drawing is that _effective_ randomness due to lack of knowledge does not imply that the course of the disease in a particular individual is not ultimately deterministic. It doesn’t imply that we must throw up our hands in hopelessness at the possibility of understanding other significant factors that may be important in determining the likely outcome. ---
**Author:** ![ThelmaLou](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thelmalou/32/390_2.png) [@ThelmaLou](https://boards.straightdope.com/u/ThelmaLou)\ **Post date:** [April 21, 2020, 10:54pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/16 "2020-04-21T22:54:33Z")
Article in The Atlantic online. Presumably COVID-related articles are available to non-subscribers. I don’t know if you have to register or anything. It’s a LONG article. [ **Why Some People Get Sicker Than Others** _COVID-19 is proving to be a disease of the immune system. This could, in theory, be controlled._](https://www.theatlantic.com/health/archive/2020/04/coronavirus-immune-response/610228/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%253A+TheAtlantic+%2528The+Atlantic+-+Master+Feed%2529) > [@](#): > > … > COVID-19 is, in many ways, proving to be a disease of uncertainty. According to a new study from Italy, some 43 percent of people with the virus have no symptoms. Among those who do develop symptoms, it is common to feel sick in uncomfortable but familiar ways—congestion, fever, aches, and general malaise. Many people start to feel a little bit better. Then, for many, comes a dramatic tipping point. “Some people really fall off the cliff, and we don’t have good predictors of who it’s going to happen to,” Stephen Thomas, the chair of infectious diseases at Upstate University Hospital, told me. Those people will become short of breath, their heart racing and mind detached from reality. They experience organ failure and spend weeks in the ICU, if they survive at all. > > Meanwhile, many others simply keep feeling better and eventually totally recover. > … > > Though SARS-CoV-2 (the new coronavirus) isn’t reported to invade the brain and spine directly, its predecessor SARS-CoV seems to have that capacity. If nerve cells are spared by the new virus, they would be among the few that are. When the coronavirus attaches to cells, it hooks on and breaks through, then starts to replicate. It does so especially well in the cells of the nasopharynx and down into the lungs, but is also known to act on the cells of the liver, bowels, and heart. The virus spreads around the body for days or weeks in a sort of stealth mode, taking over host cells while evading the immune response. It can take a week or two for the body to fully recognize the extent to which it has been overwhelmed. At this point, its reaction is often not calm and measured. The immune system goes into a hyperreactive state, pulling all available alarms to mobilize the body’s defense mechanisms. This is when people suddenly crash. > … > > Half of the patients with COVID-19 who end up in the intensive-care unit at New York–Presbyterian Hospital stay for 20 days, according to Pamela Sutton-Wallace, the regional chief operating officer. (In normal times, the national average is 3.3 days). Many of these patients arrive at the hospital in near-critical condition, with their blood tests showing soaring levels of inflammatory markers. One that seems to be especially predictive of a person’s fate is a protein known as D-dimer. Doctors in Wuhan, China, where the coronavirus outbreak was first reported, have found that a fourfold increase in D-dimer is a strong predictor of mortality, suggesting in a recent paper that the test “could be an early and helpful marker” of who is entering the dangerous phases. > > These and other markers are often signs of a highly fatal immune-system process known as a cytokine storm, explains Randy Cron, the director of rheumatology at Children’s of Alabama, in Birmingham. A cytokine is a short-lived signaling molecule that the body can release to activate inflammation in an attempt to contain and eradicate a virus. In a cytokine storm, the immune system floods the body with these molecules, essentially sounding a fire alarm that continues even after the firefighters and ambulances have arrived. > > At this point, the priority for doctors shifts from hoping that a person’s immune system can fight off the virus to trying to tamp down the immune response so it doesn’t kill the person or cause permanent organ damage. As Cron puts it, “If you see a cytokine storm, you have to treat it.” > … > > \ > … > > While America’s deepest health disparities absolutely would require generations to undo, the country still could address many gaps right now. Variation in immune responses between people is due to much more than age or chronic disease. The immune system is a function of the communities that brought us up and the environments with which we interact every day. Its foundation is laid by genetics and early-life exposure to the world around us—from the food we eat to the air we breathe. Its response varies on the basis of income, housing, jobs, and access to health care. > > The people who get the most severely sick from COVID-19 will sometimes be unpredictable, but in many cases, they will not. They will be the same people who get sick from most every other cause. Cytokines like IL-6 can be elevated by a single night of bad sleep. Over the course of a lifetime, the effects of daily and hourly stressors accumulate. Ultimately, people who are unable to take time off of work when sick—or who don’t have a comfortable and quiet home, or who lack access to good food and clean air—are likely to bear the burden of severe disease. > … ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [April 22, 2020, 2:11am UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/17 "2020-04-22T02:11:34Z")
> [@Riemann](#): > > A prominent innate source of variation in immune response is the Major Histocompatibility Complex, aka Human Leukocyte Antigen - google **MHC haplotype** or **HLA haplotype**. This makes me wonder something…I’m enrolled in the bone marrow registry, and a handful of years back I got a letter from the registry begging me to renew my commitment to being a donor because I have an extremely rare HLA profile. They noted that I will probably never match anyone, but if I do, I may be someone’s only match so that’s why it’s important to stay a potential donor (I thought we couldn’t back out until we were 61, but I guess some people do); and apparently reading between the lines I’m screwed if _I_ ever needed bone marrow. Would having an really uncommon HLA profile be helpful here? I’m guessing not since I get other respiratory viruses, but I’ve also _never_ had a stomach bug despite how prolific those are so I figure my immune system does have some quirks. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 22, 2020, 2:54am UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/18 "2020-04-22T02:54:32Z")
> [@elfkin477](#): > > Would having an really uncommon HLA profile be helpful here? There are two effects here. The straightforward one is that different HLA haplotypes will just by chance be better or worse when you are exposed to a new pathogen. This is just a function of the variation in the sequence and shape of the HLA molecules, not of their frequency in the population. In this static respect, before the pathogen has had time to evolve significantly, there’s no reason that a rare haplotype confers any advantage. Your particular sequence and shape of HLA molecules may be better or may be worse. But then there’s a dynamic evolutionary process. Over time, a pathogen will tend to evolve to evade immune systems with relatively common HLA haplotypes, simply through encountering them more frequently. At that stage, after the pathogen has been subject to natural selection in human hosts and evolved significantly, a rare HLA haplotype is likely to be an advantage. A pathogen can’t evolve to evade something it has never encountered before. At this early stage of SARS-CoV-2 in human hosts, I would doubt that the rarity of your HLA haplotype conveys any advantage against SARS-CoV-2 simply by virtue of its rarity. It will just be a matter of chance whether it’s better or worse. But the rarity of your HLA haplotype will confer a statistical advantage in later waves of infection after the virus has evolved significantly and adapted to the human population. You have a statistical advantage against _all_ pathogens. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [April 22, 2020, 3:03am UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/19 "2020-04-22T03:03:42Z")
> [@elfkin477](#): > > …I’m guessing not since I get other respiratory viruses, but I’ve also _never_ had a stomach bug despite how prolific those are so I figure my immune system does have some quirks. Your rare haplotype gives you a probabilistic advantage, other things being equal, against any pathogen that has been evolving in human hosts for a significant time. But it’s only a statistical advantage - there are many other factors that may predominate and make you more or less susceptible to any specific pathogen. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [April 22, 2020, 12:38pm UTC](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273/20 "2020-04-22T12:38:34Z")
[Here’s an article about a link between nitrogen dioxide levels and COVID-19](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151460/)fatalities. It maps pretty well to population density, but that would have more of an influence on infection rates and not fatalities. Air pollution damage may be a contribution factor in how deadly this thing is. [Next page](https://boards.straightdope.com/t/any-new-news-on-why-this-is-severe-lethal-to-some-and-not-others/852273.md?page=2)