In blood donation, there is this term 'deferral period' wherein a donor is not allowed to donate blood at a specific range of time for reasons such as recent immunization, surgery, etc. According to the Philippine Society for Microbiology and Infectious Diseases, 'deferral' or 'waiting period' is required for the patient safety consideration. This is because blood from a recently vaccinated donor may contain an infective agent which although not harmful to the donor, but may theoretically pose a risk to patients who are immune-suppressed or immunocompromised.

Due to this deferral period, it is assured that the blood that is transfused to the recipient is assured in terms of quality and safety of the blood products. Additionally, there are further tests performed in the blood to screen for pathogenic agents that may put the recipient in increased risk or harm. In recent literatures, there are no evidence of transfusing recently immunized blood to patients as there are protocols for deferral on blood banks.

Timing of blood donation among donors who received covid-19 vaccines. (2021, March 16). Retrieved February 24, 2023, from https://www.psmid.org/timing-of-blood-donation-among-donors-who-received-covid-19-vaccines/

Zabeida, A., Lebel, M. H., Renaud, C., Cloutier, M., & Robitaille, N. (2019). Reevaluating immunization delays after red blood cell transfusion. Transfusion, 59(9), 2806-2811. doi:10.1111/trf.15433