People might have to donate their own blood and store it.
https://www.verywellhealth.com/what-is-an-autologous-blood-donation-189962
Autologous Blood Donation for Surgery
Autologous blood donations are those in which the donor and recipient are the same person. Learn the uses, benefits, and risks of this type of transfusion.
https://www.verywellhealth.com/what-is-an-autologous-blood-donation-189962