SARS-CoV-2 preferentially infects blood group A cells, according to research published in Blood. The findings provide the first direct link between blood group A expression and increased SARS-CoV-2 infection.

“Many studies have demonstrated that the first polymorphism described in the human population, ABO(H) blood group antigens, are associated with increased risk of SARS-CoV-2 infection,” the researchers wrote in their report.  “Within the viral surface spike protein, the [receptor binding domain (RBD)] is responsible for recognizing host ACE2, allowing viral entry and infection. However, the RBD also bears remarkable structural and sequence similarity to an ancient family of proteins called galectins. Galectins are carbohydrate binding proteins previously shown to engage ABO(H) antigens.”

The researchers hypothesized that the SARS-CoV-2 RBD may exhibit binding characteristics toward ABO(H) similar to those of galectins. To test this, they compared the glycan binding specificity profiles of RDBs of SARS-COV-2 variants with those of galectins.

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The study demonstrated that the RBDs of SARS-CoV-2, including Delta and Omicron variants, showed specificity for blood group A. The researchers also found that both the Delta and Omicron variants displayed a preferential ability to infect blood group A expressing cells, with Omicron showing the highest selectivity compared with the SARS-CoV-2 wildtype strain.

When the team preincubated blood group A cells with a blood group binding galectin, it subsequently inhibited the enhanced SARS-CoV-2 infection of  the blood group A cells, whereas preincubation with a galectin that does not recognize blood group antigens did not impact SARS-CoV-2 infection.

“These results demonstrate a direct effect of blood group A on viral infection and answer a fundamental question regarding the increased sensitivity of blood group A individuals to SARS-CoV-2,” concluded the researchers. “While blood group A can influence SARS-CoV-2 infection, this increase can vary, ranging from a 25-50% increase in infection depending on the variant tested.”

Disclosure: One study author declared affiliations with biotech, pharmaceutical, or device companies. Please see the original reference for a full list of authors’ disclosures. 


Wu SC, Arthur CM, Jan HM, et al. Blood group A enhances SARS-CoV-2 infection. Blood. Published online June 27, 2023. doi:10.1182/blood.2022018903