@Eddie_Cliff @AaronGoodman33 There is a Cochrane review from 2017 https://t.co/kvfUjWCLup. And since then RCT by Tay et al. in HSCT-recipients (PMID 32083994) and an observational study by Chantepie et al. in ICU-setting (PMID 27861958)
However, in low-income countries the risk of a blood donation being positive for HIV, hepatitis C, or syphilis is approximately 1%, and the risk of it being hepatitis B positive is approximately 4%.
Due to changes in surgical practices, medical use of blood is now the major use of red blood cells in high-income countries.
It is given by injection into a vein.