Study reveals why people with blood group A are ‘slightly more likely’ to acquire COVID-19

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Disclosures:
Stowell reports consulting and/or speaking roles with Alexion, Argenex, Cellics Therapeutics, Grifols and Novartis. The other authors report no relevant financial disclosures.

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Key takeaways:

• Blood group status may influence an individual’s risk for COVID-19.
• COVID-19’s preference for blood group A cells adds to growing evidence that blood group status may influence risk for a variety of infections.

Researchers have identified a direct correlation between blood group A and increased risk for COVID-19 infection, according to study results published in Blood.

The COVID-19 virus interacts directly with the blood group A antigen — a carbohydrate structure that decorates the surface of cells of an individual with this blood type, according to Sean R. Stowell, MD, PhD, associate professor in the department of pathology at Harvard Medical School.

“This makes the cell surface ‘stickier’ for the virus. As a result, when a blood group A individual is exposed to the virus, it is more likely that it will attach to and then find its way into the cell,” Stowell told Healio. “This doesn’t mean that blood group O individuals cannot get infected — they absolutely can. It simply means that, all else being equal, blood group A individuals are slightly more likely to get infected with the virus.”

Rationale and methodology

From the beginning of the COVID-19 pandemic, studies have shown individuals with blood group A appeared more likely to become infected, according to Stowell.

Sean R. Stowell

“However, the mechanism responsible for this increased infection risk by blood group A individuals remained unknown,” he said. “As a result, we sought to examine how a person’s blood group status may influence infection risk at a mechanistic level.”

Researchers cloned, purified and subjected COVID-19 receptor-binding domains and galectins to glycan microarray or flow cytometric analysis.

Findings

Researchers found that the addition of a protein that inhibited COVID-19 from recognizing certain blood group antigens inhibited the virus’ preference for infecting blood group A cells but had no effect on blood group O cells, according to a press release.

Results also showed that a different protein that did not block the recognition of blood group antigens appeared to have no infection-inhibiting effects on blood type A cells or blood type O cells.

Implications

The findings suggest that blood group status may influence an individual’s risk for infection with COVID-19 due to the ability of the virus to directly engage the blood group A antigen, Stowell told Healio.

“It is important to reiterate that this does not mean that the virus can’t infect blood group O individuals or individuals of other blood group types. It simply means that blood group A individuals may be slightly more likely to become infected once exposed,” he said.

“These findings also have interesting implications regarding why different blood types even exist,” he added. “The preference of COVID-19 for blood group A adds to growing evidence that blood group status can influence risk for a variety of infections. As the impact of blood type on infection risk depends on the pathogen and, unlike COVID-19, many pathogens are only present in certain parts of the world, associations between different pathogens and blood groups may account for the distinct distributions of blood groups found throughout the world.”

Understanding how blood group antigens impact viral infection in more detail will be important, Stowell said.

“As new variants of the virus emerge, the impact of blood group antigens on viral infection could increase or decrease, but we simply do not know,” he said. “However, as the COVID-19 pandemic has taught us, understanding as much as possible about how the virus works can be incredibly powerful if similar viruses or a variant of COVID-19 emerges that causes a similar level of concern for human health. Understanding the potential influence of blood group antigens in more detail on other types of infection will be the focus of future studies.”

References:

For more information:

Sean R. Stowell, MD, PhD, can be reached at [email protected].