What’s the rarest blood type

Less than one in 160 million people share the blood type Rh-null, that’s a total of 43 worldwide. Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh (inherited protein found on the surface of red blood cells) system.

People with Rh-null blood share one very important quality with the O-negative blood type, they are universal blood donors, which means their donated blood can be given to anyone. However, both groups can both only receive a blood transfusion from someone within the same blood group. 

The International Reference Laboratory for Blood Groups (IBGRL), based in Filton, UK, has a database of all known people who have the Rh-null blood type. This database exists is to ensure that if a blood transfusion is required by a member of the Rh-null blood group, it can made logistically possible. In theory this database is a great idea, however people with Rh-null blood are spread out across the world, for example, you’ll find the Rh-null blood type in places as far apart as Japan, Brazil, Ireland, and the United States. Seeing as people with Rh-null blood are spread out across the world, this can make it very difficult to acquire this specific type of blood type, if it is needed urgently. If someone with Rh-null blood has to undergo a scheduled operation, blood donation will planned and undertaken with sufficient time beforehand, as donated blood can be stored for up to 45 days if necessary.

As for the most common blood types, A, B, AB and O, with their positive and negative variants, the most frequently found blood types in the  world are A+, O+ and B+, but the distribution varies greatly from country to country. For example, in Spain, 36% of the population is O+, 34% A+ and 8% B+. These proportions are similar in other European countries. Whereas, B+ blood type is particularly plentiful in countries such as Saudi Arabia (33 %), India (31 %), Japan (20 %) and Taiwan (24 %). The O-negative, a universal donor, has an important presence in Europe. 6% of the population of France and Germany have this blood type, 7% in Italy and 9% in Spain. O-negative blood is very rare in Asia, for example, only 2% of the population of India have this blood type and even less in Japan, only  0.15% of the population.