Backgrounder: Donor Testing - Human Immunodeficiency Virus (HIV)
Nucleic acid testing (NAT) is a highly precise test used to detect human immunodeficiency virus (HIV-1 and HIV-2) as well as hepatitis C virus (HCV), hepatitis B virus (HBV) and West Nile virus (WNV) in blood.
NAT greatly reduces the length of time a virus can go undetected in a person who is infected. However, there is still a short window period that exists after acquiring a new infection, during which the virus would not be detected by laboratory tests and an individual could transmit the virus through blood.
During screening, all blood, plasma, and platelet donors are asked questions about sexual behaviour. If they’ve had anal sex with new and/or multiple sexual partners in the last three months, they will be required to wait three months from when they last had anal sex to donate. The three-month time frame encompasses the window periods for testing of various sexually transmitted viruses, including HIV, HBV, and HCV.
In addition to testing every donation, we rely on our donors to be forthcoming about their exposure risks when completing the donor eligibility screening criteria, which is part of a multi-tiered safety system designed to protect recipients.
The window period is the time shortly after an individual has acquired a new infection, but the virus cannot yet be detected by laboratory tests. There is a risk that if someone donates blood during the window period, laboratory tests would not detect the virus and the infectious agent could be transmitted to a blood recipient. Blood donor education and our comprehensive donor screening process aims to reduce residual risk.
There are approximately zero to three HIV positive donations a year, with close to one million donations tested. All HIV positive donations are removed from the supply. For more information, read our annual surveillance report.
There have been no cases of transfusion-transmitted HIV in Canada since implementation of testing in 1985.
Since Canadian Blood Services began managing Canada’s blood system in 1998, there has not been any recorded instance of transmission of blood-borne viruses HIV, HBV, or HCV.
Canadian Blood Services is nationally responsible for a secure system of life essentials for transfusion and transplantation that’s safe, reliable, accessible, and sustainable. Emerging risks and best practices are monitored continuously to ensure that our blood and blood products are of the highest quality. Ensuring the safety of both donors and recipients is paramount, and that is why Canadian Blood Services has a comprehensive donor screening process. This process includes asking donors about potential exposure to transfusion transmissible infectious agents and testing every donation for various infectious agents that may be transmitted by blood transfusion, including human immunodeficiency virus (HIV).
Why it is important
Before the introduction of testing in the mid-1980s, a great number of Canadians received blood products infected with HIV, Hepatitis C and Hepatitis B. The Canadian Red Cross Society (responsible for Canada’s blood supply at that time) introduced donor eligibility screening criteria that deferred certain communities deemed to be at a higher risk of acquiring HIV and other transfusion-transmissible infections from donating blood, including gay, bisexual, and other men who have sex with men.
To this day, Canadian Blood Services continues to take a multi-tiered approach to safety that includes extensive screening, strict donor selection criteria and state-of-the-art testing technology.
Since we began managing Canada’s blood system in 1998, there has not been a single recorded instance of blood-borne infection from HIV, Hepatitis B or Hepatitis C.
Canadian Blood Services uses antibody testing and nucleic acid testing (NAT) to test every donation for HIV-1 and HIV-2. While this technology is sophisticated, there is a brief period shortly after an individual acquires a new infection, during which HIV is not detectable. If an individual were to donate blood during this window period in the early stages of infection, the testing process would not detect the virus and that donation would be infectious to a patient.
During the blood donation process, a small amount of blood is kept for testing at one of our two testing sites.
If a sample is identified as having HIV, additional confirmatory testing is performed. Canadian Blood Services will then notify the donor of the results and provide further information to the donor and their health care practitioner(s). We will also follow steps to report the results to public health (this is a mandatory requirement in Canada) and discard all products made from that donation.
FOR MORE INFORMATION
To learn more about Canadian Blood Services, contact: 1-877-709-7773