FAQ: Information for health professionals on safety of transfused blood collected from COVID-19-vaccinated donors

NOTE: this information reflects evidence available at time of publication.

1.  Is it safe to be transfused with blood components from a donor who has received one of the four current, Health Canada-authorized COVID-19 vaccines?

Last updated: July 28, 2021

Yes. Blood collected from donors who have been vaccinated with any of the four Health Canada-authorized COVID-19 vaccines is safe. Canadian Blood Services liaises with blood operators from around the world in conducting ongoing hemovigilance to detect any potential, emerging blood transfusion safety signals related to COVID-19 vaccines. There have been no reports of adverse transfusion reactions that can be attributed to a COVID-19 vaccine received by the donor, even as the majority of eligible Canadians have now received at least one dose of vaccine.

All current Health Canada-authorized COVID-19 vaccines are non-live vaccines and blood donated by individuals who have received a COVID-19 vaccine poses no risk for COVID-19 infection. There are no known COVID-19 vaccine-attributable harmful effects to a recipient of transfused blood collected from a vaccinated individual. Blood donors must be healthy and meet all other donor eligibility criteria on the day of donation and all blood must meet all pre-release quality and safety criteria.

Health Canada has neither recommended nor mandated any restrictions on blood collected from COVID-19-vaccinated donors, including donor deferral after receiving any of the currently authorized COVID-19 vaccines. The U.S. FDA takes a similar stance. This is also consistent with Canadian Blood Services’ donor eligibility criteria for other non-live vaccines, for which donor deferral is not required, and is in line with the practice of other blood operators.  

Canadian Blood Services’ number one priority is the health of the transfusion patient. As part of our mandate to provide a safe, accessible blood supply to Canadians, all new vaccines are assessed by medical professionals at Canadian Blood Services and Héma-Québec, taking into consideration Health Canada recommendations and scientific evidence.

You can find more information at COVID-19 vaccines and blood donation.

2.  At a patient’s request, can I request blood from a donor who hasn’t been vaccinated against COVID-19? 

Last updated: July 28, 2021

No. Because the blood component label does not indicate the vaccination status of the donor, it is not possible to select blood components for transfusion that came from an unvaccinated donor. Information on a blood component label is limited to what is relevant to its appropriate selection and safe use, including information as required by the regulator, Health Canada, or as recommended by relevant blood safety standards. Furthermore, such a request is also operationally unfeasible as a growing majority of Canadians have received at least one dose of vaccine. See question 1 for more on the safety of blood from donors who have been vaccinated against COVID-19.

If a patient requires a blood transfusion, the patient or their legal guardian should discuss their concerns with their health-care provider. Every patient has the option to accept or decline transfusion, following the hospital’s informed consent policy, processes, and procedures.  

You can find more information at COVID-19 vaccines and blood donation on blood.ca. 

3.  Is it safe to transfuse blood from a donor vaccinated with a COVID-19 vaccine that differs from the vaccine received by the transfusion patient? Is there a potential for an adverse reaction if the vaccines “mix”?

Last updated: July 28, 2021

Yes, it is safe to transfuse blood from a donor who has been vaccinated with a COVID-19 vaccine that is different from the one the patient has received. The vaccine administered to a blood donor and the vaccine given to a blood recipient do not interact.

COVID-19 vaccines are designed to remain predominantly localized in the injection site muscle tissue, with very little or no systemic distribution of vaccine constituents, including in blood. Vaccination results in cellular production of low levels of SARS-CoV-2 spike protein, which is very effective at stimulating a robust cellular and humoral immune response that protects the vaccinee against COVID-19 infection. Depending on the donor’s immune response to vaccine and the time between donor vaccination and blood donation, donated blood may contain variable levels of COVID-19 antibodies produced by the donor’s immune system; these are not harmful to a blood recipient.

4.  Should autologous blood donation be considered when a patient does not want to receive blood from a donor who has received a COVID-19 vaccine?  

Last updated: July 28, 2021

The donation of blood by a patient for their own future use (generally for a scheduled elective surgery) is called preoperative autologous donation. Autologous blood donation is only done with a physician’s order and only in a limited number of circumstances when blood from donors does not meet the patient’s needs, such as for a patient with a rare blood type.  For the reasons described above, requesting autologous blood donation for a patient who wishes to avoid receiving blood from a vaccinated donor would not be appropriate.

For more about preoperative autologous donations, including reasons for its declining use and its benefits and risks, see Chapter 16, Preoperative Autologous Donation, of the Clinical Guide to Transfusion, and a statement on perioperative autologous donation from Canada’s National Advisory Committee on Blood and Blood Products.

5.  Will donating blood reduce the effectiveness of the COVID-19 vaccine?

Last updated: July 28, 2021

No. There is no evidence that donating blood will reduce the effectiveness of the COVID-19 vaccine. There is no evidence to indicate that donation of a blood product will lead to lowered vaccine protection in the blood donor. Immune responses in vaccinated donors are complex and do not rely solely on circulating antibodies or cells in the blood.

As with other non-live vaccines, passively acquired immune constituents (both cellular and antibody) in transfused blood resulting from COVID-19 vaccination of donors do not significantly alter the effectiveness of the recipient’s subsequent immune response to COVID-19 vaccine, or the effectiveness of pre-existing immune protection that the recipient may have, either from prior COVID-19 infection or vaccination. Similarly, these passively acquired immune constituents from transfused blood components (excluding COVID-19 convalescent plasma) are unlikely to provide any protection against COVID-19 infection.

You can learn more at COVID-19 information on blood.ca; scroll down to the Questions and answers: Blood and Plasma Donation section.