WHAT’S BEING CLAIMED:
- Blood type A is linked to severe coronavirus infection while blood type O to lower risks, according to scientists.
- The evidence on this blood type connection is tentative and still does not prove a blood type connection, other scientists said.
- Experts explain that blood type is one of the factors that contributes to a person’s susceptibility to infectious diseases, but this blood type connection still requires verification.
In Europe, a team of scientists published data that point to a possible explanation for the difference in disease severity observed in coronavirus patients. The genetic analyses illustrate probable connections between the blood type and the severity of symptoms. This publication is available at the New England Journal of Medicine.
The published data associate blood type A to increased probabilities of contracting coronavirus and developing severe symptoms compared to non-A blood types, while blood type O is associated with lower risks. These research findings were derived from comparing genetic data belonging to about 2,000 patients showing severe symptoms to several thousand other patients with mild or without symptoms.
While this establishes a potential involvement of the ABO blood-group system to coronavirus infections, the research still does not prove a blood type connection. This only confirms a previous report about this connection from China.
“Most of us discounted it because it was a very crude study,” said Dr. Parameswar Hari, a blood specialist at the Medical College of Wisconsin. It is possible that these research findings are important to further understand the virus, but other scientists urge caution.
Dr. Eric Topol, head of the Scripps Research Translational Institute in San Diego said that the evidence on this blood type connection is “tentative … it isn’t enough of a signal to be sure.”
Dr. Mary Horowitz, scientific chief at the Center for International Blood and Marrow Transplant Research, explains that this an individual’s blood type “[is] determined by proteins on the surface of your red blood cells,” that correspond to the four main blood groups: A, B, AB and O.
This potential involvement of the ABOO blood-group system is based on the immune response when antigens come into contact with substances that are unfamiliar to the body. Dr. Hari said that blood group O is better able to trigger immune response upon detecting foreign bodies. The doctor also said that during the Severe Acute Respiratory Syndrome (SARS) outbreak, blood group O is also linked to less severe virus infection.
Dr. David Valle, director of the Institute of Genetic Medicine at Johns Hopkins University, explains that blood type is one of the factors that contributes a person’s susceptibility to infectious diseases. Examples include cholera, recurrent urinary tract infections from E. coli, and Helicobacter pylori infection that could lead to stomach cancer.
“It’s a provocative study. It’s in my view well worth publishing and getting out there,” but it needs verification in more patients,” Dr. Valle said.