COVID Readiness: Know Your Blood Type

Do you know your blood type? 

Most people get their blood type (A, B, AB, or O), plus their Rh factor, so they know about possible blood donations.  O negative is the universal donor, and AB positive is the universal recipient. 

If you have ever given blood, you carry a card (I have one from the American Red Cross) that shows your blood type.

Knowing one’s blood type was all the craze back when the book Eat Right for Your Type came out several decades ago (it has recently been updated). I found that most of the advice rang true for myself and my friends and family members.  I got the kits, which were around $10 and involved a simple finger prick at home, to get the blood types for anyone that wanted to know.

Now there is some interesting information coming out about blood type and severity of symptoms from COVID. 

I’m intrigued, but not entirely sold, on the science.  I can say that the theory (that O negative folks get off the hook symptoms wise) did seem to happen in our family. And folks like me and my hubby, who are B positive, struggled a bit more through the symptoms of COVID.


I was curious enough to enlist my outstanding intern’s support on human performance aspects (including tracking blood markers) to review the scientific literature. I’ll put his finding below.  There is no harm in becoming more educated.  When it comes down to the magic formula I’ve used to work with tens of thousands of people to improve their nutrition and health (through my nonprofit Nurture), it is simple: education, inspiration, and choice.

Now I’ll share the research that my intern found about blood type and COVID.

Guest post by Larsen Bier

Certain studies have concluded that an association between blood type, infection with COVID-19, and the severity of those infections are very likely. Given that these associations probably exist, AB groups are more susceptible to infection than O groups. Rh-positive groups were more susceptible to infection than Rh-negative groups, with a combination of O types and Rh-negative types being the least susceptible to infection. 

The association between blood type and COVID-19 severity is slightly less clear than the relationship between blood type and infection prevalence; however, the data nonetheless suggest that O types and Rh-negative types are generally at an advantage in developing less severe infections.

The studies disagree with each other on a few other points. The first research (Zhao et al.) studying blood type and COVID-19 concluded that A types were particularly susceptible to the virus; however, a later study from Zietz et al. concluded that A types were only more susceptible to infection but not intubation or death compared to O types. It ought to be noted, however, that the 95% confidence intervals for Zietz et al.’s data include values that have the potential to change those conclusions. 

Another study from Ellinghaus et al. also found lower odds of mechanical ventilation for non-O types, seemingly contradicting the conclusions drawn from Zhao et al.’s analysis. Ellinghaus et al.’s conclusions were not statistically significant at the 5% level, meaning that it is not considered too improbable to have happened by pure chance (The odds of the correlation appearing randomly when there is none are greater than 5%). 

Yet another study, this one by Hoiland et al., determined that A and AB types are at an increased risk of becoming infected or developing a severe case of COVID-19 compared to O and B types, which is more in line with Zhao et al.’s original conclusion than any of the others’.

Despite the fact that these studies do not come to an entirely clear consensus, they generally agree on one crucial point: we need more evidence. The data that have been gathered are indeed thought-provoking. However, more studies and reviews need to be done to verify the accuracy of the findings. While there does appear to be an association between blood type and susceptibility to COVID-19, the specifics of why and to what extent currently elude researchers. 

At the moment, the real impact of blood type on susceptibility to COVID-19 appears to be small. Zietz et al. approximate that the absolute risk difference between blood groups is between 0.1% and 8.2% (Meaning that the most susceptible group is likely at maximum only 8.2% more susceptible than the least susceptible group and at minimum 0.1% more susceptible). At the moment, these data are not comprehensive enough to guide medical practice. They will not impact the treatment or handling of the coronavirus. Ray et al. note that at most, a very small proportion of COVID-19 infections are prevented by blood type, a statement supported by Zietz et al.’s risk assessment. Additionally, even if one does possess a low-risk blood type, they still ought to exercise caution not to contract COVID-19. 

Although this news should not change your lifestyle or make you less cautious about COVID-19, it still could help to know your blood type if you do contract COVID-19. Especially for non-O types, it might be a good idea to consider extra self-care during your recovery period. (See this series of blog posts for more information):

  1. Let Food Be Thy Medicine
  2. Stay Well Hydrated
  3. Sleep is the Best Medicine
  4. Start or Boost your Spiritual Practice
  5. Ask for Support for Mental Wellness 
  6. Take Care of Your Skin
  7. Don’t Fear a Fever
  8. Sweat
  9. Take Time for Professional Development
  10. Breathe
  11. Keep it Out of Your Lungs

O types should exercise caution and respond as their condition progresses and seek emergency care if needed.

This podcast interview called “Blood, Sweat, and Fears” might also be of interest!


Ellinghaus, D. et al. Genomewide association study of severe Covid-19 with respiratory failure. N. Engl. J. Med. (2020).

Michael J. Schull, Marian J. Vermeulen, Alison L. Park, et al. Association Between ABO and Rh Blood Groups and SARS-CoV-2 Infection or Severe COVID-19 Illness: A Population-Based Cohort Study. Ann Intern Med. 0;0 [Epub ahead of print 24 November 2020]. doi:10.7326/M20-4511

Ray, Joel G., et al. “Association between ABO and Rh Blood Groups and SARS-CoV-2. Infection or Severe COVID-19 Illness.” Annals of Internal Medicine, 24 Nov.

American College of Physicians, doi:10.7326/M20-4511. 

Ryan L. Hoiland, Nicholas A. Fergusson, Anish R. Mitra, Donald E. G. Griesdale, Dana V. Devine, Sophie Stukas, Jennifer Cooper, Sonny Thiara, Denise Foster, Luke Y. C. Chen, Agnes Y. Y. Lee, Edward M. Conway, Cheryl L. Wellington, Mypinder S. Sekhon; The association of ABO blood group with indices of disease severity and multiorgan dysfunction in COVID-19. Blood Adv 2020; 4 (20): 4981–4989. doi:

Zhao, J. et al. Relationship between the ABO blood group and the COVID-19 susceptibility. medRxiv. (2020).

Zietz, M., Zucker, J. & Tatonetti, N.P. Associations between blood type and COVID-19 infection, intubation, and death. Nat Commun 11, 5761 (2020).

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