Why do we have different blood types — and do they make us more vulnerable to Covid-19?

Why do we have different blood types — and do they make us more vulnerable to Covid-19?

Most humans fall into one of four blood groups — A, B, AB or O.

Ordinarily, your blood type makes very little difference in your daily life except if you need to have a blood transfusion.

However, some studies have people wondering if blood type affects coronavirus risk. One, for instance, suggests that people with Type A may have a higher risk of catching Covid-19 and of developing severe symptoms while people with Type O blood may have a lower risk.

study published this week counters some these early findings, a reminder that scientific discovery is an evolving process. Researchers at Massachusetts General Hospital and Beth Israel Deaconess Hospital published a study Thursday that found no evidence that blood type affects whether someone develops severe symptoms (defined as intubation or death) from a coronavirus infection.

Other past research indicates that certain blood groups may affect vulnerability to other diseases, including cancer.