What The Relationship Between Blood Type And Coronavirus Susceptibility Means For Future Treatments

A new study that has come out of China claims to have found that people with type A blood may be more susceptible to the novel Coronavirus (COVID-19). What does this mean for patients, doctors, and researchers, and should people with A blood types be worried?

The study was conducted by a group of Chinese researchers and analyses 2,173 patients who contracted the COVID-19 virus from three hospitals in Wuhan and Shenzhen and then compared them to the bloods types of the two general populations in the area. Their meta-analysis found that people who were part of “blood group A had a significantly higher risk for [contracting] COVID-19 compared with non-A blood groups.”

As outlined in the study, the normal population in Wuhan has a blood type distribution of:

• Type A - 31%
• Type B - 24%
• Type AB - 9%
• Type O - 34%

Comparatively, Wuhan residents who had contracted COVID-19 had a blood type distribution of:

• Type A - 38%
• Type B - 26%
• Type AB - 10%
• Type O - 25%

These percentage distribution differences held relatively consistent with the Shenzhen populations as well.

“The work is very preliminary, but it is biologically plausible that different blood groups might vary in their susceptibility to COVID-19.” Say Dr. William A. Petri, Jr., M.D., Ph.D., of the University of Virginia, after reviewing the study.

But why would someone’s blood type make them more susceptible to COVID-19? The answer, Petri explains, has to do with how proteins on the surface of Coronaviruses bind to the different sugars on the surface cells, which go hand in hand with a person’s blood type. “We know some of the Coronaviruses that infect cattle have proteins on their surface that bind to sugars and sugars are what dictate blood group antigens*. If you are blood group A, you have an extra sugar on the surface of your cells called anacitosal glucosamine, which you don't have if you are blood group O.”

Dr. Kirsten L. Hokeness, of Bryant University, who also reviewed the study, goes on to explain, “The ABO blood-group system is part of the immune system.” Interestingly, the core of how our immune system fights infection, as well as the variability of how different infections affect different people, is found in our blood types.

This blood type - immune system connection has been explored by immunologists for over 100 years. “The concept that individuals with different ABO blood Groups would differ in their susceptibility or resistance to viral and bacterial infections and diseases has been explored since the early 1900s.” Says Dr. Hokeness, “A lot of this work has been done in malaria but there have been a number of other bacteria and viruses that have been studied as well including hepatitis and Norovirus. The fact that interaction with pathogens has over time caused the ABO blood Group to evolve over thousands of years could suggest that there is an interaction between the two systems.”

So should people with blood type A be more worried than the rest of us? Both Dr. Petri and Dr. Hokeness agree - No.

“If you are blood group A you shouldn't be more scared.” Says Dr. Petri, “The study shows very small changes in susceptibility. It goes from 31% of people who reportedly didn't have COVID-19 versus 38% who did. So it's tiny changes and it hasn't been replicated and the study has not yet been peer reviewed. So while it's interesting and it kind of makes sense biologically, it might not be true. Regardless, if it is true, it probably does not have a huge impact on overall susceptibility.”

“At this point, people with blood type A do not need to be worried since this does not appear to be any concrete driver of infection.” says Dr. Hokeness, “I would not let blood type be something that would put fear or rest assuredness into people. We should all still be considered vulnerable to this infection despite blood type or any other quantifiable trait.”

Between the fact that the paper has not yet been peer reviewed, the small sample size, and relatively small variability of infection rates found in the study, people with blood type A do not have a much higher cause for concern. However, the study does point to some interesting factors regarding how treatment could be developed to fight COVID-19.

“There are a lot of microorganisms that cause infection that interact with human cells by binding to sugars on the surface of those cells.” Says Dr. Petri, “The best example of that is influenza. The flu virus binds to the sugar on the surface of human cells called sialic acid.” Continuing that, “Tamiflu is a drug that inhibits the binding ability of influenza to these sugars and that is a great example where the recognition of neuraminic acid’s (an acidic amino sugar in the blood) interaction helped identify an effective antiviral medicine.”

This study, and future studies like it, could eventually identify ways to block the COVID-19 virus before it takes over. “Better understanding how the virus gets access to host cells, could help in treatment development.” Say Dr. Hokeness, “And if these basic science studies can tell us a bit more about how the virus unlocks the host receptor or that these antibodies can block that interaction, we could use that information in order to create a treatment. But there is certainly a lot more data that we need to know at this point.”

So instead of causing further anxiety among the population, the study is instead signalling the early stages of antiviral treatment research and should therefore be more of a sign of hope than further despair.

Full coverage and live updates on the Coronavirus