- New research suggests there could be a link between a patient's blood type and their risk of a severe
coronavirus infection. - An analysis of thousands of coronavirus patients in Spain and Italy showed that people with blood type A are 50% more likely to develop severe symptoms and require ventilation.
- The researchers also noted that people with blood type O are less likely to contract severe infections.
A patient's blood type could impact how hard they're hit with the coronavirus.
New research suggests that people with blood type A are 50% more likely to develop severe
That study, published last week in the New England Journal of Medicine, also found that patients with blood type O have a 50% reduced risk of severe infection compared to patients with other
"A genetic test and a person's blood type might provide useful tools for identifying those who may be at greater risk of serious illness," Francis Collins, director of the National Institutes of Health who was unaffiliated with the study, wrote in a blog post Thursday.
People with blood type A face a higher risk
The research examined the genetic codes of of more than 1,600 coronavirus patients undergoing treatment for severe coronavirus at seven medical centers in Italy and Spain. They found that a region of the participants' genomes that helps code for blood type was linked to a patient's chances of developing severe symptoms.
In general, your blood type – A, B, AB, or O – depends on the presence or absence of proteins called A and B antigens on the surface of red blood cells. People with O blood have neither antigen. The presence of those A and B antigens in our blood is a genetic trait inherited from our parents.
All people also have either a positive or negative blood type, depending on whether they have a third protein called the Rh factor. If you have blood type A, for example, and have the Rh protein, you're A positive.
The researchers found that coronavirus patients whose genes code for blood type A were 50% more likely than people with other types to experience respiratory failure.
They also found "a protective effect for blood group O as compared with the other blood groups."
O and A are the most and second-most common blood types, respectively. About 48% of Americans are O positive or O negative, and 37% of Americans are A positive or A negative, according to the Oklahoma Blood Institute.
Further research into blood types and COVID-19 is needed
Not all experts are convinced of a link between blood types and severe coronavirus infections.
Dr. Eric Topol, director of the Scripps Research Translational Institute, told the Associated Press that the evidence is "tentative ... it isn't enough of a signal to be sure."
Most genetic studies involve a larger group of participants than the recent one did, so other scientists should look at groups of patients to see if they find the same links, Topol added.
According to Collins, some NIH research groups recently launched a study to look for similar genetic variants in 5,000 coronavirus patients in the US and Canada.
But the new research does align with the findings from two earlier, non-peer-reviewed studies.
In March, a study of more than 2,173 coronavirus patients from three hospitals in Wuhan and Shenzhen, China, found that patients with blood type A were at a higher risk for COVID-19 infections compared to people other blood types. The researchers also observed that people with blood type O had a lower risk for infection.
In New York, researchers analyzed 1,559 patients in April and found a similar trend: A higher proportion of infected patients had blood type A and a lower proportion had type O.
Blood type may play a role in a patient's susceptibility to severe infection from other diseases too, including rotaviruses and noroviruses that can cause diarrhea; Helicobacter pylori, which can cause ulcers and stomach cancer; and SARS, another coronavirus that spread globally in 2002 and 2003.
Some research has suggested that people with blood type O were more resistant to SARS infections. A 2005 study in Hong Kong found that most individuals infected with SARS had non-O blood types.