Forty million times a year, red cells are transfused to patients. These are by far the most frequently transfused blood component. Unfortunately, they are also the most common blood component to be in short supply. Particularly in the United States, surgeries and other patient treatments are being postponed because blood collectors don't have enough red cells in supply for patients who need them.

While there are several "blood substitutes" in development, these drugs, if cleared by the Food and Drug Administration, will only be useful in very specific treatments. Nothing will ever substitute the need for people to donate their red cells.

Red cells are "type-specific." People have varying blood types - O, A, B, or AB. Type-specific means that a patient must be transfused with red cells from a donor of the same blood type. There are some exceptions to this rule. For instance, type O blood can be transfused to a person with any blood type. For this reason, people with type O blood make excellent red cell donors.

Red cell donors in the U.S. are volunteer donors. The red cells donated are only used for transfusion to patients.