Link between blood type and COVID-19 susceptibility, study finds

People with blood type O may have a lower risk of novel coronavirus (COVID-19) infection and reduced likelihood of severe outcomes, including organ complications, if they do get sick, according to a new study published in the journal Blood Advances.

Researchers compared Danish health registry data from more than 473,000 individuals tested for COVID-19 to data from a control group of more than 2.2 million people from the general population. Among the COVID-19 positive, they found fewer people with blood type O and more people with A, B, and AB types.

The study results suggest that people with blood types A, B, or AB may be more likely to be infected with COVID-19 than people with type O. The researchers did not find any significant difference in rate of infection between A, B, and AB types. Since blood group distributions vary among ethnic subgroups, the researchers also controlled for ethnicity and maintained that fewer people with blood type O tested positive for the virus, according to the study.

In a separate smaller retrospective study, the researchers also found that people with blood groups A or AB appear to exhibit greater COVID-19 disease severity than people with blood groups O or B. For this study, the researchers examined data from 95 critically ill COVID-19 patients hospitalized in Vancouver, Canada. They found that patients with blood groups A or AB were more likely to require mechanical ventilation, suggesting that they had greater rates of lung injury from COVID-19. They also found more patients with blood group A and AB required dialysis for kidney failure.

Together, the findings suggest that patients in these two blood groups may have an increased risk of organ dysfunction or failure due to COVID-19 than people with blood types O or B, the researchers said. Furthermore, while people with blood types A and AB did not have longer overall hospital stays than those with types O or B, they did remain in the intensive care unit (ICU) for a longer average time, which may also signal a greater COVID-19 severity level.

As the pandemic continues, the global biomedical research community is working urgently to identify coronavirus risk factors and potential therapeutic targets. The potential role of blood type in predicting risk and complications of COVID-19 infection has emerged as an important scientific question. The new studies add evidence that there may be an association between blood type and vulnerability to COVID-19. However, additional research is needed to better understand why and what it means for patients, the researchers said.

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