Skip to main content

Genes, Blood Type Tied to Risk of Severe COVID-19

Posted on by Dr. Francis Collins

SARS-CoV-2 virus particles
Caption: Micrograph of SARS-CoV-2 virus particles isolated from a patient.
Credit: National Institute of Allergy and Infectious Diseases, NIH

Many people who contract COVID-19 have only a mild illness, or sometimes no symptoms at all. But others develop respiratory failure that requires oxygen support or even a ventilator to help them recover [1]. It’s clear that this happens more often in men than in women, as well as in people who are older or who have chronic health conditions. But why does respiratory failure also sometimes occur in people who are young and seemingly healthy?

A new study suggests that part of the answer to this question may be found in the genes that each one of us carries [2]. While more research is needed to pinpoint the precise underlying genes and mechanisms responsible, a recent genome-wide association (GWAS) study, just published in the New England Journal of Medicine, finds that gene variants in two regions of the human genome are associated with severe COVID-19 and correspondingly carry a greater risk of COVID-19-related death.

The two stretches of DNA implicated as harboring risks for severe COVID-19 are known to carry some intriguing genes, including one that determines blood type and others that play various roles in the immune system. In fact, the findings suggest that people with blood type A face a 50 percent greater risk of needing oxygen support or a ventilator should they become infected with the novel coronavirus. In contrast, people with blood type O appear to have about a 50 percent reduced risk of severe COVID-19.

These new findings—the first to identify statistically significant susceptibility genes for the severity of COVID-19—come from a large research effort led by Andre Franke, a scientist at Christian-Albrecht-University, Kiel, Germany, along with Tom Karlsen, Oslo University Hospital Rikshospitalet, Norway. Their study included 1,980 people undergoing treatment for severe COVID-19 and respiratory failure at seven medical centers in Italy and Spain.

In search of gene variants that might play a role in the severe illness, the team analyzed patient genome data for more than 8.5 million so-called single-nucleotide polymorphisms, or SNPs. The vast majority of these single “letter” nucleotide substitutions found all across the genome are of no health significance, but they can help to pinpoint the locations of gene variants that turn up more often in association with particular traits or conditions—in this case, COVID-19-related respiratory failure. To find them, the researchers compared SNPs in people with severe COVID-19 to those in more than 1,200 healthy blood donors from the same population groups.

The analysis identified two places that turned up significantly more often in the individuals with severe COVID-19 than in the healthy folks. One of them is found on chromosome 3 and covers a cluster of six genes with potentially relevant functions. For instance, this portion of the genome encodes a transporter protein known to interact with angiotensin converting enzyme 2 (ACE2), the surface receptor that allows the novel coronavirus that causes COVID-19, SARS-CoV-2, to bind to and infect human cells. It also encodes a collection of chemokine receptors, which play a role in the immune response in the airways of our lungs.

The other association signal popped up on chromosome 9, right over the area of the genome that determines blood type. Whether you are classified as an A, B, AB, or O blood type, depends on how your genes instruct your blood cells to produce (or not produce) a certain set of proteins. The researchers did find evidence suggesting a relationship between blood type and COVID-19 risk. They noted that this area also includes a genetic variant associated with increased levels of interleukin-6, which plays a role in inflammation and may have implications for COVID-19 as well.

These findings, completed in two months under very difficult clinical conditions, clearly warrant further study to understand the implications more fully. Indeed, Franke, Karlsen, and many of their colleagues are part of the COVID-19 Host Genetics Initiative, an ongoing international collaborative effort to learn the genetic determinants of COVID-19 susceptibility, severity, and outcomes. Some NIH research groups are taking part in the initiative, and they recently launched a study to look for informative gene variants in 5,000 COVID-19 patients in the United States and Canada.

The hope is that these and other findings yet to come will point the way to a more thorough understanding of the biology of COVID-19. They also suggest that a genetic test and a person’s blood type might provide useful tools for identifying those who may be at greater risk of serious illness.


[1] Characteristics of and important lessons from the Coronavirus Disease 2019 (COVID-19) outbreak in China: Summary of a report of 72 314 cases from the Chinese Center for Disease Control and Prevention. Wu Z, McGoogan JM, et. al. 2020 Feb 24. [published online ahead of print]

[2] Genomewide association study of severe Covid-19 with respiratory failure. Ellinghaus D, Degenhardt F, et. a. NEJM. June 17, 2020.


The COVID-19 Host Genetics Initiative

Andre Franke (Christian-Albrechts-University of Kiel, Germany)

Tom Karlsen (Oslo University Hospital Rikshospitalet, Norway)


  • Soozie says:

    Then how does COVID affect someone who has type B+?

    • Sherrie Wells says:

      What about someone who has AB – blood type?

      • Marie Serrao Mastromatto says:

        I have AB negative blood. How does this affect my chances of getting COVID 19?

        • AB neg says:

          Higher chance of getting it and If We get it, Higher risk of needing ventilator is what I get out of this research Being rare isn’t always fun

          • Indiana Native says:

            That’s type “A” not AB, there is a difference. I read AB positive is in the category of having a higher percentage of not catching it…

    • JannaG says:

      I have the same question. I’m B+ and I haven’t been sick with a respiratory illness in over 5 years. I haven’t even needed to call in sick to work for 22 years. So, maybe our blood is set on B-ing positive?

    • brian t nichols says:

      Type o blood doesn’t carry any antigens. This is why it can be donated to so many other blood types. Type o can only receive blood from other type 0’s. Other blood types carry antigens, and type o will attack the antigens rejecting the blood. It must have something to do with that. What, I don’t know.

      • Danielle says:

        I think you’re talking about O negatives not O positives.

      • Carolyn U says:

        If Type O folks can donate their Type O to folks who have Type A blood, is it possible to give a Type O blood transfusion to a Type A person to control the severity of COVID-19 infection?

  • hellopk says:

    You may have huge amounts of inquiries concerning the novel corona virus and one of these inquiries will be tied in with seeing how this infection spreads.

    To comprehend this you will initially need to think about certain nuts and bolts of this infection. The epic corona virus is SARS-CoV-2 which is its clinical name. This is an intense respiratory disorder corona virus 2. The inception of this infection follows to a group of different infections that are dependable to cause respiratory issues and respiratory disorder.

    The epic corona virus is another strain. This implies the infection is curious about with the human safe framework. This likewise implies there is still no antibody for this infection.

    At the point when an individual interacts with the corona virus then he is sick with the infection COVID-19. The infection is respiratory. It implies that respiratory beads are the bearer of this infection.

    Here is the means by which the novel corona virus gets spread starting with one individual then onto the next. You ought to likewise take care to comprehend the insurance strategies from this new infection strain.

  • John says:

    Can you name the exact genes so that we may look through our 23andme data to see if we are at risk?

  • george c lewis says:

    What about people with negative blood types?

    • Esmeralda says:

      Good question. They didn’t see any correlation of the Rh type with Covid19.
      I answered above, they saw other genes, though.

  • John Hasty says:

    These findings don’t surprise me seeing how the most common blood type is A.

    • Scott R says:

      That is not correct, Type O+/- is the most common human blood type:

      African-American: 47 percent
      Asian: 39 percent
      Caucasian: 37 percent
      Latino-American: 53 percent

      African-American: 4 percent
      Asian: 1 percent
      Caucasian: 8 percent
      Latino-American: 4 percent

      African-American: 24 percent
      Asian: 27 percent
      Caucasian: 33 percent
      Latino-American: 29 percent

      African-American: 2 percent
      Asian: 0.5 percent
      Caucasian: 7 percent
      Latino-American: 2 percent

      African-American: 18 percent
      Asian: 25 percent
      Caucasian: 9 percent
      Latino-American: 9 percent

      African-American: 1 percent
      Asian: 0.4 percent
      Caucasian: 2 percent
      Latino-American: 1 percent

      African-American: 4 percent
      Asian: 7 percent
      Caucasian: 3 percent
      Latino-American: 2 percent

      African-American: 0.3 percent
      Asian: 0.1 percent
      Caucasian: 1 percent
      Latino-American: 0.2 percent

      • SUSAN SHAW says:

        Interesting to see these figures, especially as the group most affected by Covid 19 seems to be the BAME populations. Yet, if correct, according to the blood group numbers above, all of these groups have higher numbers of Blood group O than Caucasians, which seems inconsistent with the report findings.

        • Viv says:

          I would think that if the disease is not genetically inclined to certain members of the population by race then perhaps the increase in cases could be cultural. That is to say are there certain customs or behaviors that place one population group at a higher risk than others?

        • Bubba says:

          It looks like the subjects were all European. There may be other genetic factors at play, uncommon or non-existent in this sample, that impact African-Americans more than those of European descent.

        • Catherine Ebeling MSN, Public Health, RN says:

          All things being equal, this study may make sense, but considering the massive number of variables tied to each individual’s overall health, their immune health, their metabolic health and even mental health, this study seems rather insignificant. All those other variables carry far more weight.

      • Chris says:

        Solid reply!

      • Jan Turetsky says:

        You are giving percentages but they are meaningless unless you specify what they mean. They are percentages of what?

    • Ariel Haberman says:

      John: The most common blood type is “O” – FYI

  • xloni says:

    What about AB Rh-? How is this type affected?

  • DR. SAUMYA PANDEY, PH.D. says:

    Genetic determinants of Covid-19 susceptibility with emphasis on A, B, AB and O blood-types in populations of distinct genetic and metabolic profiles is a burning area of biomedical research; the crisp highlights from the NIH USA Director, Dr. Collins, deserve an applause with credits to the innovatively-designed clinical research study team!

  • Kaye says:

    I am A- and I had the corona virus (03/29/20). Not hospitalized, but wasn’t sure I’d make it out alive. Still having some breathing issues.

    • SHEILA Bridget D. says:

      Ok, I’m A-. What should I do, to lower my chances of contracting the virus? I’m 63, other than high cholesterol, have no issues.

  • Krystal says:

    I’m Rh- , and also have Lupus (SLE) how I’m I affect by covid19?

    • Suzanne says:

      Following! I’m RH – and have RA, fibromyalgia and Lyme disease which is currently dormant. I’m curious how it would effect me!

  • Chris W. says:

    I have AB+ what are my chances for covid 19?

  • Kate M says:

    Am curious if being on an Ace2 inhibitor has any effect on the virus?

    • Christie Paramedic says:

      ABSOLUTELY. It is why people with compromised lungs are at higher risk. Diabetes, obesity and heart disease have also been proven to be a major factor in the severity of the virus. This explains why Hispanic and African Americans are at a higher risk for severe cases. The are genetically predisposed to these risk factors.

  • Zerah says:

    Now that we’re properly scared… tell all us A’s how to mitigate having type A blood???

    • Catherine Ebeling MSN, Public Health, RN says:

      Cover all the other more heavily weighted variables. Weight, metobolic factors, blood sugar, heart disease risk, diabetes risk, kidney disease, and lung disease. Get rid of inflammatory foods, lose weigh if needed, get your blood sugar under control, get plenty of sleep, exercise, get plenty of sunshine and vitamin D. Take vitamins, eat a ton of vegetables. Relax.

  • Peggy P. says:

    I have type 0- blood & a compromised immune system from COPD & pulmonary hypertension. What are the chances of a woman 68 yrs. old in this shape surviving covid19?

  • Robert M. says:

    This blood type information is interesting.
    I am O+, but also have Lupus SLE and I have taken Plaquenil (Hydroxychloquine) for twenty years.

    My daughter had covid-19 with covid toes. Not sure of her blood type. I know that if my wife is O+, then my daughter will be also.

  • Steve Long says:

    Having A blood type just puts you at a slightly higher risk of a severe reaction to COVID-19; it doesn’t definitively mean that you will. There are other risk factors as well, and the way to deal with these risk factors is all the same: minimize social events particularly indoors, wash your hands frequently, avoid touching your face. Until there is a proven vaccine, those behaviors should be your new normal.

  • Andreia] says:

    Chile has 85.5% of the population of blood type O. Only 8.7% of type A. Why do they have the biggest mortality rate per million in the world?

  • Anna Fowler says:

    How does the virus affect Rh-negative blood type?

    • Allart says:

      Rh vs ABO: Rh factor(s) are separate gene products from ABO – they just happen to be found on the same location – the red blood cell surface. ABO factors are variants of sugar side groups linked to, and extending from, a surface protein and result from three variants of the same enzyme. There are several Rh factors, at least one of which is a protein that transports ammonium ions.
      A vs AB vs B vs O: A draft publication from China by Zhao et al 2020 of over 2100 COVID-19 patients found type A folks to be most susceptible to death vs type O. Data for types B and AB were statistically not as tight, but B was similar to O and more interestingly, AB may be the least susceptible of the four blood so much for the anti-A hypothesis. The answer may lie in that chromosome 9 region….
      As for susceptibility, by the time we reach age 70, our ability to generate new, educatable cytotoxic T cells (those that detect viruses) may average something like 10 percent of what it was at age 20 (numbers off the top of my head)…. It gets worse with age, so our ability to fight off new infections steadily declines. Steroids further suppress T cell formation. Other factors are the dose of virus to which we are exposed and the presence any pre-existing immunity against microbes that look a lot like COVID-19, which may be why some people, some even very old, don’t even show symptoms.

  • thomas breiter says:

    a 50 percent greater risk of needing oxygen support or a ventilator should they become infected with the novel coronavirus. In contrast, people with blood type O appear to have about a 50 percent reduced risk ….isn’t that the same???

  • Andrea Ouse says:

    Since Type O blood seems to reduce the severity of COVID-19, how likely is it for a person with this blood type to be an asymptomatic carrier that can still transmit the disease?

  • Evelyn Reed says:

    Such an informative read Dr. Francis! Blood type seems to have a significant impact on the severity of COVID-19. But the reason behind is still not clear. Although, some believe that the susceptibility of the virus to impact the cell is affected by the cell structure.

  • 1 2 3

Leave a Reply to SheilaCancel reply