In general, the rarest blood type is AB-negative and the most common is O-positive. Here's a breakdown of the most rare and common blood types by ethnicity, according to the American Red Cross. A person's blood type is based on whether or not they have certain molecules or proteins — called antigens — on the surface of their red blood cells, according to the National Institutes of Health. Two of the main antigens used for blood typing are known as "A antigen" and "B antigen. Individuals with type AB blood have both; people with type O blood have neither.
Why is type O blood the Universal donor?
Blood types universal donor and recipient – NatureWord
In these instances doctors reach for the universal blood type. The universal blood type is O negative O-. Donors with type O- blood have the unique power to help anyone in need of a blood transfusion. These two donation types allow O- donors to maximize their donation and make the largest impact for patients in need. While O- is the universal blood type for whole blood and red blood cell transfusions, it is not the rarest blood type nor is it the universal blood type for platelet or plasma transfusions. People with AB type blood positive or negative are universal plasma donors. Plasma from AB donors can be given to patients with any blood type, making it extremely important for those in need.
What Is the Universal Recipient Blood Type?
Blood groups are complex chemical systems found on the surface of blood cells. Identification of the correct blood group is important to prevent reaction following transfusion. Each system is inherited independently of the other.
Now, researchers analyzing bacteria in the human gut have discovered that microbes there produce two enzymes that can convert the common type A into a more universally accepted type. If the process pans out, blood specialists suggest it could revolutionize blood donation and transfusion. People typically have one of four blood types—A, B, AB, or O—defined by unusual sugar molecules on the surfaces of their red blood cells. If a person with type A receives type B blood, or vice versa, these molecules, called blood antigens, can cause the immune system to mount a deadly attack on the red blood cells.