According to Stanford Blood Centre, there are a total of 8 types of blood groups, which are categorised based on the presence ...

The ratio of patients with type AB blood who had serious cases of COVID-19 was found to be 1.4 times higher than that for people with AB blood in the second group.

Negative blood types are particularly valuable because they are not common. With less than 2% (one in 50 donors) of the population having B negative blood type, it is among the rarest blood types.