Here is some info from the red cross...Universal donors are those with an O negative blood type. Why? O negative blood can be used in transfusions for any blood type.
Type O is routinely in short supply and in high demand by hospitals – both because it is the most common blood type and because type O negative blood is the universal blood type needed for emergency transfusions and for immune deficient infants.
Approximately 45 percent of Caucasians are type O (positive or negative), but 51 percent of African-Americans and 57 percent of Hispanics are type O. Minority and diverse populations, therefore, play a critical role in meeting the constant need for blood.
Types O negative and O positive are in high demand. Only 7% of the population are O negative. However, the need for O negative blood is the highest because it is used most often during emergencies. The need for O+ is high because it is the most frequently occurring blood type (37% of the population).
The universal red cell donor has Type O negative blood. The universal plasma donor has Type AB blood. For more about plasma donation, visit the plasma donation facts. There are very specific ways in which blood types must be matched for a safe transfusion. The right blood transfusion can mean the difference between life and death.
Every 2 seconds someone in the US needs a blood transfusion.
Use the interactive graphic below to learn more about matching blood types for transfusions.
Also, Rh-negative blood is given to Rh-negative patients, and Rh-positive or Rh-negative blood may be given to Rh-positive patients. The rules for plasma are the reverse.
