People with the first blood group — universal donors — are people whose blood can be transfused to any recipient without fear of “gluing together” red blood cells.
Universal they are very conditional. It is allowed to transfuse blood, erythromass, serum or plasma of group 0 (group 1) to patients who have blood of another group, only in emergency cases, in the absence of transfusion media (mass for transfusion) of the same group and only in small and medium doses.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.