Knowing blood type is important

Forty-three percent of Americans don’t know their blood type according to a 2019 survey by Quest Diagnostics — fewer than how many have memorized their Wi-Fi password. But recent links between blood type and COVID19, or even susceptibility for other diseases, mean you might want to know your type.

A recent study by Harvard Medical School researchers based at Massachusetts General Hospital found blood type is not related to the severity of symptoms of COVID19. However, the study also found symptomatic people with some blood types may have a higher chance of testing positive for COVID-19.

So few people know their type, not because that information isn’t available, but likely because no health care provider has ever told them, said Chancey Christenson, associate director of the University of Chicago Blood Center and medical director of clinical pathology informatics.

Christenson, also an associate professor in transfusion medicine, said if you’ve had your blood drawn, your blood type is probably already on file.

Blood type is determined by the carbohydrate chains — also known as antigens — that hang off your red blood cells, Christenson said. There are A and B antigens.

Type A blood has the A antigen and Type B blood has the B antigen. AB blood has both antigens and Type O blood has neither.

Knowing whether you are Type A, B, AB or O is most important in the event you need a blood transfusion. “If you ever need blood, it’s simpler if you already know your type,” he said.

But knowing your type may also help you understand more about your health, Christenson said.

Type O blood is known as the universal donor — meaning any blood type can accept O blood — because it has no antigens, Christenson said. Having no antigens on the red blood cells also makes people with Type O blood less prone to bacterial infections, he said.

Christenson said people with Type O blood are also at a lower risk for heart and vascular diseases, but are more likely to get norovirus.

“The type of your blood is showing you what is happening in the rest of your body,” Christenson said.

“The ABO antigens are everywhere.” He said they can be found in blood vessels and gut lining.

Type A blood has a higher clotting factor, Christenson said, which makes for an increased risk of heart disease, heart attack and DVT. He said people with Type A blood may have more pronounced hangovers.

People with type AB are more predisposed to these clotting problems, Christenson said.

If you have Type B blood, you may have an increased risk for pancreatic cancer and a lower risk of meningitis, he said. Group B people may also experience better digestion.

“You can’t change your blood type,” Christenson said. “So, it’s a risk factor just like any other risk factor.”