There are four main blood groups (types of blood):

Blood groups A, B, AB and O. are determined by the genes inherited from parents. In addition, each group is either Rhesus RhD positive or RhD negative {absence of RhD]. This results in eight possible combinations.

Group O is found in approximately 50% of all Zimbabweans, however, RhD positive is found in approximately 98% of the African population, and only 2% are RhD negative. In the Caucasian population RhD positive occurs in 85% and RhD negative in 15%.

Group O is in the greatest demand as it can be considered a universal donor, because in emergencies, or times of shortage, it can be transfused into persons of blood group A; B or AB, of the correct Rhesus D type. NBSZ prepares Red Cells by removing plasma, which may contain antibodies - anti A & anti B and replaces the plasma with an additive solution to improve blood flow and increase its life span.