Sexual behaviour-based screening

Frequently asked questions

What are the sexual behaviour-based eligibility questions?

All donors are asked if they’ve had new and/or multiple sexual partners in the last three months. If they answer yes to either, they are then asked if they’ve had anal sex with any of these partners.  

If they have, they will be required to wait three months from when they last had anal sex to donate. If they have not and meet all other eligibility criteria, they will be able to donate.  

Why the focus on anal sex?

Statistically, anal sex has a significantly higher chance of HIV transmission per sex act than vaginal or oral sex. 

This does not account for individuals’ own safe sex practices but is based on an evidence-based approach to overall risk. 

Why will you ask about anal sex with multiple partners?

The chance of a new/recent infection of HIV that cannot be detected in our testing (window period infection) increases with new sexual partners and multiple sexual partners.  

Statistically, anal sex has a significantly higher chance of HIV transmission per sex act than vaginal or oral sex. Multiple sexual partners can increase the chance of HIV transmission. 

Why will you still be deferring people who have used PrEP/PEP in the last 4 months?

Pre-exposure prophylaxis (PrEP) is a highly effective medication regimen used for HIV prevention.   

In people taking PrEP or post-exposure prophylaxis (PEP), low levels of HIV may be missed in testing. We rely on accurate HIV testing as part of our multi-layered approach to safety.    

There needs to be more research on how PrEP and PEP affect HIV testing. At this time, individuals who take PrEP or PEP are unable to donate for 4 months from last use.    

This is an issue impacting blood operators worldwide. Tests used to detect HIV and other viruses are manufactured by other companies, not Canadian Blood Services. Work to understand the true impact of PrEP and PEP medication regimens on HIV tests can only be completed in collaboration with or directly by the manufacturers of the test, who hold the licensing for these products.   

Canadian Blood Services and other blood operators are highly interested in ongoing studies assessing impact of PrEP on testing assays.    

Why did it take you so long to implement sexual behaviour-based screening?

We know that the slow pace of changes to donor criteria that have excluded many gay, bisexual and other men who have sex with men has been painful and frustrating for many. It has taken time to collect the evidence needed to apply to our regulator Health Canada to make changes to these criteria.   

In Canada, blood donor eligibility criteria are developed within a strict, evidence-informed regulatory framework that focuses on patient safety.   

Health Canada alone has the authority to approve changes to donor selection criteria that impact human safety or the safety of blood. For Canadian Blood Services to apply to make a change, we needed to be able to provide evidence that the proposed change would not compromise patient safety.  

As a blood operator, Canadian Blood Services is responsible for gathering sufficient evidence to make a request for change to Health Canada. Our changes are informed by the available science and the frequency and pattern of health events in a population (epidemiology).   

To make this change to gender-neutral sexual behaviour-based screening for all donors, we needed to have a bedrock of evidence in support of new criteria. The MSM Research Program, findings from the international research community, epidemiological data and our own extensive modelling informed our submission to make this change.   

How do you know it’s safe to change your screening approach to asking all donors about sexual behaviour?

This criteria change will not compromise the safety or adequacy of Canada’s blood and plasma supplies.     

Canadian Blood Services has a profound responsibility to the patients we serve. Safety is paramount in everything we do.     

The criteria will continue to defer those with a higher chance of acquiring a new HIV infection. Other criteria already in place identify additional risk factors for acquiring HIV, and these will continue to be applied.      

Health Canada alone has the authority to approve changes to donor eligibility criteria that affect human safety or the safety of blood.     

For Canadian Blood Services to change the eligibility criteria, we needed to provide strong evidence to the regulator, Health Canada, that the proposed change will not compromise safety. 

The evidence we have gathered through the MSM Research Program, which received funding from Health Canada, as well as findings from the international research community, epidemiological data and our own risk modelling support making this change. 

Currently the chance of HIV being introduced to the blood system is extremely low, and according to the evidence, the new criteria will maintain safety. 

Isn’t all blood tested?

Yes, every donation is tested for an array of infections that could be transmitted by blood transfusion. But, no test is perfect, and there are some infections for which there’s no test.  For example, there are no Health Canada-approved tests for malaria or Zika for blood production.   

One reason we have such a safe blood system in Canada is the layering of a donor screening questionnaire with donation testing.   

Tests that are used to test every blood donation have a limitation called the “window period”. The window period is the time between when a donor has acquired a new infection and is able to transmit it, to the time a lab test can reliably detect the infection.  If an HIV or hepatitis infection is newly acquired, testing may not pick it up. The donor questionnaire is critical in helping identify people who may have had a recent new exposure to an infection of concern, such as HIV or hepatitis C. 

Why is screening necessary, shouldn’t everyone who wants to contribute be able to donate?

Canadian patients depend on us to provide a safe, secure and cost-effective blood system that meets their full range of health-care needs. Our screening practices are in place to protect both patients and donors. All donors are subject to the same eligibility criteria. These criteria ensure that we accept donations only from individuals from whom it is safe for patients to receive blood. To protect the safety of patients who rely on blood products for treatment, we often have to make difficult decisions, based primarily on scientific evidence of risk, about who can and cannot donate blood.

Donating blood isn’t the only way to support patients. There are many ways that those who may not be eligible to give blood can work with us to make a valuable contribution to patients in need, such as financial donations, by registering as an organ and tissue and/or as a stem cell donor. 

I participated in the MSM Plasma Program in London or Calgary. How does this change affect me?

Thank you for participating in the MSM Plasma Program. You have not only helped patients in Canada, but you have also helped drive this eligibility change and inform our work to ensure positive donor experiences. On Sept. 11, 2022, sexual behaviour-based screening was implemented for all donors, regardless of gender or sexual orientation. This means any plasma donations that were in a 60-day hold were automatically sent to be made into specialized medicines.  

We encourage you to continue donating plasma with the new criteria, or you could consider donating whole blood instead.  

Can men who have sex with men donate organs or stem cells?

Regulations for organ and stem cell donations are different than those for blood donation. Men who have sex with men can register to become organ donors through their provincial organ donation registry Organ and tissue donors are assessed on screening criteria ranging from general health to specific risk behaviours. Each case is assessed in consultation with the attending physician and based on patient consent. To find out more about organ donation, visit the Organs and Tissues section of our website.  

MSM who are between the ages of 17 and 35 can also join the Canadian Blood Services Stem Cell Registry. Similarly, to organ donations, stem cell matches require input from an attending physician as well as patient consent. To find out more about stem cell donation, visit the Stem Cells section of our website.  

What about trans individuals?

Trans donors are no longer asked whether they’ve had lower genital gender-affirming surgery.    

Trans donors are now able to register in their gender. Due to limitations of the binary registration computer software system, non-binary donors will still need to register in a binary gender.    

We are working on changes to our processes in consultation with trans and non-binary community members as well as the registration software owner to improve this registration and screening process.   

Why don’t you ask about condom use?

Condom use, while an excellent sexual health practice, isn’t an evidence-based method of screening donors because condoms are not always effective and can break or slip. We also know from research that questions about condom use are less reliably answered because people don't always recall correctly.   

It is important to note our current criteria and the proposed sexual behaviour-based screening questions are not comprehensive in asking about safe sexual practices, such as condom use, that can effectively mitigate the risk of acquiring HIV.   

Our questionnaire is designed to be applied as broadly as possible to screen a large number of potential donors and identify the possibility of new exposures to certain viruses within the window period of our testing platforms. It can’t comprehensively screen each donor on their individual safe sex practices. 

What about undetectable equals untransmissible (U=U). Why can’t HIV+ people donate if their viral load is undetectable?

It’s amazing that HIV care has reached a point where people’s viral loads can be undetectable.    

Undetectable equals untransmissible only applies to sexual transmission of HIV. Unfortunately, even those who have an undetectable viral load may transmit the virus through blood transfusion.    

The chance of transmission is much higher with a unit of blood due to the large volume of a blood transfusion and the much higher total amount of virus present. 

Why don’t you ask about receptive vs. insertive anal sex?

It is true that receptive anal sex has a much higher chance of HIV transmission per sex act than insertive anal sex.  

However, when we did implementation studies on asking donors about receptive anal sex, the term was not well understood and the question was inconsistently answered.   

For the safety of our blood and plasma supplies, it is of vital importance that donor screening criteria are easily understood by all donors.   

What about people who are in exclusive relations with multiple people (e.g. they practice polyamory/polyfidelity)? Can they donate?

We recognize that some people may be in sexual relationships with multiple people where their partners are not new partners. 

With the implementation of sexual behaviour-based screening, people with multiple partners, who have engaged in anal sex with one or more of their partners in the last three months, will be required to wait three months from when they last had anal sex to donate.

What is Health Canada’s role in changing the eligibility criteria for men who have sex with men?

Health Canada is the regulator of Canada’s blood system. Health Canada alone has the authority to approve changes to donor selection criteria that impact human safety or the safety of blood. For Canadian Blood Services to apply to make a change, we must be able to provide evidence that the proposed change will not compromise safety.

Once a change is approved, we are often required to conduct studies to monitor the impact of the change on blood safety. For example, one research study is looking at how accurately our current donor health questionnaire screens for donors who use pre-exposure and post-exposure prophylaxis (PrEP and PEP) medications, and how the change to sexual behaviour-based screening for all donors may impact this. The levels of PrEP and PEP medications will be measured on a subset of coded blood samples from donors that meet specific criteria, using a blood sample that is routinely taken during donation. For more information about this study please contact 1 888 2 DONATE or

Research resources webpage

Two research programs provided Canadian evidence critical to support submissions to the regulator to evolve eligibility criteria.