Type-O Blood and COVID-19

The risks of developing COVID-19 appear to vary by the person, but it seems that blood type may play some role. Researchers are still trying to pin down why exactly such a disproportionate number of people with type-O blood are testing negative for the deadly virus after exposure, but they do have a couple of ideas. We have the details.

Blood Type and Coronavirus

In June of 2020, Chinese researchers at The First Hospital of Changsha and The Third Xiangya Hospital examined what appeared to be a relationship between blood type and COVID-19 prevalence. Their analysis, which they published in Clinica Chimica Acta, shows that an unusually low number of people with type-O blood have tested positive for the virus compared to others.

Of 187 patients, fewer than 22% had type-O blood, the most common blood type, whereas nearly 37% had type A and just over 33% had type B. A low number of AB blood types also tested positive, but their numbers were consistent with those of the control group. The researchers concluded that people with type-O blood are at least somewhat less likely to test positive for COVID-19, while people with type-A blood may be more likely to contract the virus.

Blood Type Plays a Role in the Immune System

The details on how and why blood type affects COVID-19 susceptibility are still sketchy, but the connection could have to do with the antibodies people with type-O blood carry. Blood type occurs because there are different types of antigens and antibodies in the blood: People with type-A blood carry antibodies against type-B blood (and vice-versa), while type-O blood carries antibodies against both A and B blood type antigens. These antigens and antibodies could have subtle effects on other immune responses, just enough to give people with type-O blood a slightly-higher-than-expected boost in COVID-19 immunity.

Previous studies have found connections between blood type and susceptibility to West Nile Virus, norovirus and rotavirus gastroenteritis. These differences may not seem like much but they may not only determine disease prevalence, but also the severity of illness post-contraction.

Type-O Blood and COVID-19 Resistance

Recently, 23andMe teamed up with GSK Medicines Research Centre in the UK to broaden the data set. They looked at stats from over 6.7 million participants, confirming what others have already found: People with type-O blood may actually be less likely to develop COVID-19. The researchers also looked at rhesus factor (Rh+/-) but weren’t able to find any additional connections.

While this study does have its flaws, the biggest being that it assumes blood types via genetic profiles rather than antigen tests and uses self-reported illnesses for its infection count, it does cover a massive number of people. If anything, it creates a springboard for more in-depth studies on the different connections between blood type and disease prevalence. A closer look at the antibodies in question could provide new avenues for both prevention and treatment in COVID-19 and numerous other deadly infections.

Remember that having reduced susceptibility isn’t the same as being immune, so people of all blood types should take precautions regardless of the stats. Mask up everyone, and let's do our best to take care of each other.

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