Surveillance Report

This annual report describes surveillance of transmissible blood-borne infections and emerging threats of concern during the calendar year of 2024. High quality and timely surveillance are essential to the safety of the blood supply. Monitoring of transmissible disease markers that the blood is tested for are central to surveillance, as is investigation of any reports of possible transfusion transmission. Horizon scanning for any new pathogens that may pose a risk ensures ongoing preparedness. Non-infectious surveillance of aspects of donor health and safety are also included.

Infectious risk monitoring

The most up-to-date tests for pathogens are used to identify infectious donations and prevent their release for patient use. In 2024, transmissible disease rates per 100,000 allogeneic donations (for direct blood transfusion) continued to be very low: human immunodeficiency virus (HIV) 0.4, hepatitis C (HCV) 7.3, hepatitis B (HBV) 8.0, human T-cell lymphotropic virus (HTLV) 1.9 and syphilis 12.2. Selective testing of donors at risk of Chagas disease identified no positive donations, and there were six donations that were positive for West Nile virus (WNV) similar to previous years. Residual risk estimates of a potentially infectious donation from a unit of blood are very low at one in 13.2 million donations for HIV, one in 72.1 million donations for HCV and one in 4.1 million donations for HBV. Lookback and traceback investigations did not identify any transfusion transmitted infections. Since 2016 nearly half of HIV positive donations were non-B subtype which is the subtype more common in heterosexuals. The most common HBV genotype was D, followed by A, B and C. These genotypes are common in particular parts of the world and likely reflect the diversity of immigrants in Canada. The most common HCV genotypes were one and three. The viral genotypes observed in donors are not dissimilar from the Canadian general population.

Source plasma is collected by apheresis to be sent for manufacturing fractionated plasma products such as intravenous immune gammaglobulins (IVIG) and albumin. In 2024, 122,214 source plasma donations were collected, mostly from repeat donors (96 per cent). Transmissible disease rates per 100,000 source plasma donations were very low: HIV 0, hepatitis C (HCV) 2.5, hepatitis B (HBV) 7.4 and syphilis 3.3.

All donors whose donation tests positive for a transfusion transmissible infection are informed by letter, and sometimes by telephone. Interviews of donors after they were notified of their positive test showed that notification was effective as most donors were aware of their positive test. Most were surprised by the positive test, and most sought medical care.  

In 2024, whole blood derived buffy coat platelets were being pathogen reduced in all regions all but eliminating the risk of bacterial contamination and by May 2024 apheresis platelets were also pathogen reduced. Non-pathogen reduced platelets are distributed on rare occasions for clinical contra-indications to pathogen reduction additives. Bacterial growth was identified in four apheresis platelet products that had not been pathogen reduced up until May. Of 495 potential peripheral blood stem cell or bone marrow donors tested, none were positive for any infectious marker. Of 290 samples from mothers donating stem cells collected from the umbilical cord and placenta (called cord blood) after their babies were born, none were positive for any infectious markers. Since 2014 donors with false reactive/unconfirmed results for HIV, HCV or HBV have been eligible to give a re-entry testing sample after six months, and if all infectious tests are negative, they may re-commence donating. As of Jan. 16, 2023, the donor re-entry program was also extended to donors who had previously tested false reactive for HTLV or syphilis. As of Dec. 31, 2024, nearly 4,000 donors have been able to donate again and have given over 40,000 donations. The donor re-entry program supports a safe blood system and provides a positive contribution to the active donor base. After removal of deferral for time spent in countries with former risk of variant Creutzfeldt-Jakob disease, over 13,000 previously deferred donors have returned, and about 8000 new donors donated due to the deferral change.

Horizon scanning

Horizon scanning activities have historically occurred at Canadian Blood Services with the maintenance of blood and stem cell emerging pathogen matrices, as well as quarterly reports. These activities collect information on a variety of variables that allow for Canadian Blood Services to prepare and plan for changing risks to blood safety and sufficiency. Since the start of the COVID-19 pandemic, Canadian Blood Services has noted a changing information landscape which became increasingly acute in late 2024. In 2024, Canadian Blood Services began planning to integrate a horizon scanning function into the developing Surveillance and Discovery Laboratory (SDL) functions. This work continues on into 2025.

The risk of a tick-borne disease, babesiosis, continues to be monitored. The parasite (Babesia microti) that causes babesiosis appears to be in the early stages of becoming established in a few places in Canada, especially in Manitoba. Travelers and former residents from malaria risk areas are temporarily deferred for malaria risk. In addition, a three-week deferral for any travel outside Canada, continental U.S., Hawaii and continental Europe reduces risk from short term travel related infections such as Zika virus.

Sexual behaviour-based screening

On Sept. 11, 2022, the three-month deferral for gay, bisexual, and other men who have sex with men was removed and replaced with deferral based on sexual risk questions that all donors must answer regardless of their gender or sexual orientation. Since implementation, seven allogeneic blood donations and one source plasma donations were HIV positive, with a similar HIV positivity rate as prior to the criteria change. Since implementation, 0.1 per cent of donors were temporarily deferred using these new sexual behaviour-based questions. Pre- and post-implementation donor compliance surveys showed compliance with the new screening questions was suboptimal. In the survey there were 0.86 per cent of donors who answered yes to the sexual risk questions before they were implemented (when most were eligible to donate) and 0.76 per cent after implementing when they should have been deferred. Pre-exposure prophylaxis (PrEP) medication is used to prevent HIV infection in at-risk individuals. Donors are deferred for oral use of PrEP in the last four months (injectable PrEP, which was approved for use in Canada in May 2024, carries a two year deferral) due to risk of false negative tests. Testing of selected donation samples for PrEP showed no evidence of PrEP use in first time male donors or HIV positive donors, but 2.3 per cent of syphilis positive donation samples and 12.2 per cent of donation samples from donors who had been deferred for PrEP use on a prior donation had positive results for PrEP. This demonstrates the difficulty of messages about PrEP use and donation which is contrary to messaging from their health care provider and public health about reducing their risk of HIV by taking PrEP. However, in spite of non-compliance shown by these two studies, HIV rates in donors to date have remained stable and low as noted above.

Donor safety

Adverse reactions to donation are rare. The most common reactions are vasovagal (fainting) and bruising. Vasovagal reactions are more common in first time donors and younger females. Deferrals for low hemoglobin are higher in females than males. The inter-donation interval for whole blood donations in females is longer than for males (84 vs 56 days) to allow more time for females to recoup their body iron levels. Starting in 2023 female donors on their 10th, 20th, or 30th etc., donations were tested for ferritin, a measure of body iron status that can indicate low body iron levels before hemoglobin drops. If ferritin was low (≤ 24 µg/L), donors were advised not to donate for at least six months and to see their health care practitioner for further testing and advice about iron supplementation. About a quarter of these female donors had low ferritin in spite of passing their hemoglobin test on donation. Low ferritin was associated with more frequent donation. After 18 months, 75 per cent of donors who had low ferritin returned compared with 86 per cent with normal/high ferritin. Deferral for low hemoglobin was reduced with longer time to return. To ensure ongoing donor iron health, ferritin testing is important for safeguarding donors.

Donor demographics

Most whole blood donations are from repeat donors. A little more than half of donors are males, and about a quarter are persons 60 years of age or older. About 45 per cent of donations are from Ontario. Based on responses to a voluntary question about race/ethnicity over a quarter of whole blood donations are from Black, Indigenous and Racialized donors. Most source plasma donations are from repeat donors. While a quarter of source plasma donors are aged 60 and over, they donated about 40 per cent of donations. A little over half of donations are from Ontario. Just under a quarter are from Black, Indigenous and Racialized donors.

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Safety of the blood supply from pathogens involves a multifaceted approach. Donor education materials on the internet and required reading just before donating explain risk factors for transmissible infections and who should not donate. Before donating blood, everyone must complete a health history questionnaire which includes questions about specific risk factors for transmissible infections. This is followed by an interview with trained staff to decide if the person is eligible to donate blood. All donations are tested for markers of transfusion transmissible agents including HIV, HBV, HCV, and syphilis. All donations except some source plasma donations are tested for HTLV (a rare cause of leukemia). WNV testing is undertaken during the at-risk period of the year (spring, summer, and fall) and in at-risk travelers during the winter. In addition, donors at risk of Chagas disease (which is transmitted by the bite of an insect in Latin America) are tested. Pathogen reduction technology has been phased in for platelet products.

Surveillance is continued watchfulness over well-defined health-related problems through systematic collection, consolidation, and evaluation of relevant data. Surveillance includes monitoring of transmissible infection testing in donors, investigation of possible transfusion transmitted infections in recipients and is related to horizon scanning for new, emerging and re-emerging pathogens. Horizon scanning is a systematic foresight examination of information that allows the scanner to identify potentially important and ill-defined new emerging or re-emerging events, risks, and threats, thereby guiding preparedness activities and support decision making processes. Monitoring the safety of donors is also essential. Although surveillance is conducted in real time over each year, final verification steps generally impose a short delay in producing a final report. This report describes Canadian Blood Services’ approach to surveillance of transmissible blood-borne infection, infectious threats, and donor safety, as well as data for the calendar year of 2024.

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The numbers of allogeneic blood donations (whole blood and platelet and transfusible plasma apheresis) from first time and repeat donors are shown in Figure 1. The majority of donations are from repeat donors (89.8%). The decreasing trend in the proportion of donations from first time donors from 11.1% in 2019 to 9.8% in 2020 to 8.3% in 2021 is reversing with 9.5% in 2022, 10.1% in 2023 and 10.2% in 2024. 

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The classical pathogens

Details of screening tests used, and dates of implementation are shown in Appendix I. In Table 1 the numbers of positive donations and the rates of positive tests per 100,000 donations are shown for 2024 by demographic groups. When a transmissible infection is detected, it is most often in a first time donor as these donors have not been tested previously and may have acquired the infection at any time in their lives. There were three HIV positive allogeneic blood donations in 2024. In the past five years, the number of HIV positive donations has ranged from zero to four per year. The rate per 100,000 donations has remained stable for HIV and the rate for repeat donations is extremely low (see Appendix II). Unlike previous years, the HTLV rate in  males was similar to females in 2024, although rates are still very low. While both males and females may acquire HTLV from their mother during birth or as a baby from breastfeeding, sexual transmission is more common from male to female, less common from female to male. Hence the rate tends to be slightly higher in females most years. There is a trend towards increased HBV, HCV, and syphilis positive first time donations (for syphilis also in repeat donations). Canada is considered a low prevalence country for HBV and HCV. Both HBV and HCV infections are more common in immigrants from higher prevalence countries where transmission risk during birth and from medical procedures and household contacts is higher, as well as sexual contact. Routine HBV vaccination also may not occur in these countries. As Canadian Blood Services works to be inclusive of donors from different ethnic groups and nationalities, a few more HBV and HCV positive donations are not unexpected. Curative treatment for HCV has been available since 2014, and more widely available since 2016 in Canada. As shown in Figure 2 below, the percentage of HCV antibody positive first time donations which are also HCV NAT positive, indicating active infection, has been decreasing. Hence the overall increase in HCV positive first time donations in recent years is likely due to old infections that either resolved spontaneously or were treated. Syphilis (first time and repeat donations) has increased from 4.1 per 100,000 donations in 2019 to 9.8 in 2020, 6.7 in 2021 and 10.7 per 100,000 in 2022, 10.4 per 100,000 in 2023, and continuing the upward trend at 12.2 per 100,000 in 2024. Syphilis cases have been increasing in the general population, but rates are not directly comparable because community cases reported by public health primarily include people who had reason to be tested (usually new infections with symptoms) whereas blood donors with syphilis positive test results include both people unaware of their infection and those who may have been infected in the past and cured. It is unlikely that syphilis could be transmitted by transfusion due to modern blood processing methods. 

Table 1. Confirmed positive donations and prevalence rates per 100,000 allogeneic donations in 2024. 

Note: Four anti-HCV of the 59 positive donations had confirmatory testing just above the lower cut-off suggestive of infections resolved in the distant past or false positive tests.
Positive (Pos); human immunodeficiency virus (HIV); Hepatitis C (HCV); Hepatitis B (HBV); Human T-lymphotropic virus (HTLV).

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All transmissible infection positive donations are destroyed. The main source of risk is when a blood donor acquired the infection too recently to be detected by testing. This is called the window period of infection. With current testing the window period is very short. For HIV and HCV, an infection would be detected within one to two weeks of a donor being infected by nucleic acid testing (NAT) and for HBV within one month. The residual risk of infection is the estimated risk of a potentially infectious donation being given during the window period. These estimates, shown in Table 2, are based on new infections (positive donations with a prior donation which tested negative within the last year) and include 2022-2024 data. The risk is currently extremely low, but of course it can never be zero.
 

Table 2. Estimated residual risk of human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV).

Risk factors

Risk factor interviews are carried out with donors who test positive for transmissible infections. The main risk factors are shown in Table 3. HIV infections are very rare in donors; therefore, it is difficult to generalize the risk factors. It should be noted that participation is voluntary and therefore there is only data for some donors, and that for many donors no risk factors were identified.

Table 3. Risk factors for infectious disease in blood donors.

Note: Not all donors are available/willing to be interviewed.

Viral genotypes

Since February of 2016 all donations positive for HIV, HBV, or HCV for which there was sufficient sample were genotyped by the Public Health Agency of Canada (PHAC) National Microbiology Laboratory in Winnipeg. Genotyping is important to understand when new or rare genotypes appear in the donors, which may suggest a shift in risk factors. The genotypes in all tested samples are shown in Table 4. Note that national genotyping reports by PHAC can lag by at least five years. In Canada most HIV-1 infections were subtype B historically, but this has been changing over the last 10 to 15 years. In heterosexuals the non-B subtypes are more common, hence the nearly half of donors with non-B subtypes (47 per cent) may reflect the former deferral of gay and bisexual men who have sex with men over the period. Different HBV genotypes are more common in different parts of the world. For example, HBV genotype A is more common in Africa and northern Europe, B and C are more common in Asia, and D in Africa, Europe, the Mediterranean and India. Hence the diversity of HBV genotypes in donors may reflect the diversity of immigrants in Canada. HCV genotype 1 (sub-types 1a and 1b) is the most common in Canada as is also seen in the donors. HCV sub-genotype 3a is the next most common in Canada, also seen in the donors. 

Table 4. Genotypes of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) positive donations 2016–2024.

Chagas disease (Trypanosoma cruzi)

Chagas disease is caused by infection with a parasite called Trypanosoma cruzi (T. cruzi). The reduviid insect that carries the parasite is found in parts of Mexico, Central, and South America. Infection can occur following a bite by the insect, be passed on from mother to child during pregnancy, or passed on by blood transfusion. Donors are deferred if they have had Chagas disease. In addition, potential donors are asked whether they, or their mother or maternal grandmother, were born in Mexico, Central America, or South America, and if they have spent a total of six consecutive months or more in Mexico, Central America, or South America. Since testing of at-risk donors was implemented in 2010, 35 T. cruzi positive donations have been identified (see Figure 3). In 2024, there were no positive donations of 7,126 tested. Notably, no donor with only travel risk (not born in a risk area or mother/grandmother born in a risk area) has ever tested positive.

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West Nile virus

West Nile virus (WNV) is a mosquito-borne virus that has been present in North America since 1999 (in Canada since 2002). Although symptoms can be severe, they are usually mild, and most people are not aware of their infection. During spring, summer, and fall, donations are routinely tested in mini pools of six donations. However, to further reduce the risk, an algorithm is applied to identify all donations from areas where West Nile virus is active, and these are tested as single donations. In 2024, 457,627 donations were tested over the spring, summer, and fall when all donations were tested, and six donations were positive, identified from July 10 to Sept. 20. Three positive donations were from Ontario, and three from the Prairies region. With only travelers tested over the winter, 60,643 donations (from Jan. 1 to May 25, 2024, and Nov. 25 to Dec. 31, 2024) were tested and none found to be positive. Note: follow up testing and interviewing of WNV-positive donors by local public health may classify some of these donors into categories other than asymptomatic. The low infection rate in 2024 WNV is similar to previous years.

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Source plasma is collected by apheresis to be sent for manufacturing of fractionated plasma products such as immunoglobulin and albumin. Because the demand for fractionated products, especially immunoglobulin, is increasing, Canadian Blood Services is collecting more source plasma. In 2024, 122,214 apheresis source plasma donations were collected. By region, 6.6 per cent of source plasma donations were collected in the Atlantic provinces while 51.2 per cent were collected in Ontario. The majority of collections were from repeat donors (96 per cent) and almost two thirds from males. Figure 4 shows the number of donations by donation status. Source plasma may currently be donated once a week.

Source plasma donations increased from 99,647 donations in 2023 and 122,214 donations in 2024. Additionally, although first time donations constituted a small proportion of the total (four per cent), the number of first-time source plasma donors per year increased from 81 to 5,038 over this period. This reflects increasing recruitment of new donors for plasma donation rather than recruiting from those already donating whole blood. In this report, donors were classified as first time based on the first time they ever donated any type of donation.

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While about 21 per cent of source plasma donors in 2024 were aged 17-29 years old, they gave only about 12 per cent of donations (see Figure 5). Conversely, about 25 per cent of donors were aged 60 years or older but accounted for 41 per cent of all donations. White donors made up 71.8 per cent of source plasma donors. Based on voluntary self-reporting of race/ethnicity, donors identifying as belonging to a Racialized group ranged from 13.1 per cent in the Atlantic provinces to 34.1 per cent in Ontario.

Table 5 shows the numbers of positive donations and the rates of donations testing positive per 100,000 plasma donations for 2024. There were no HIV positive donations in 2024, three HCV positive donations, nine HBV positive donations, and four syphilis positive donations. When a transmissible infection is detected, it is most often in a first-time donor as these donors have not been tested previously. These findings are comparable to whole blood donations.

All donations that tested positive for any transmissible disease marker were destroyed. Because the manufacturing process of source plasma includes several pathogen reduction steps, the risk of transmission of any of these infections is close to zero.

Table 5. Confirmed positive donations and prevalence rates per 100,000 source plasma donations in 2024.

Positive (Pos); human immunodeficiency virus (HIV); Hepatitis C (HCV); Hepatitis B (HBV); Human T-lymphotropic virus (HTLV).

^† Donors were classified as first time based on the first time they ever donated any type of donation.
^‡ Plasma donor centre sites do not test donations for HTLV (about 70 per cent of source plasma donations).

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In 2014, Canadian Blood Services established a donor re-entry program designed to reintegrate donors who had been indefinitely deferred due to false reactive HIV, HBV, or HCV results on either serological markers or nucleic acid tests. These false reactive results arise from the high sensitivity of blood screening tests, which can sometimes react to non-infectious components in the blood. As of Jan. 16, 2023, the program was expanded to include syphilis and HTLV.

In the re-entry program, donors with false reactive results are deferred for six months. After six months, they can return to provide a sample for re-testing. If the sample is negative for all routinely screened infectious disease markers, the donor is eligible to resume donating blood products. Deferred donors are informed about the re-entry program through a notification letter sent after their reactive test result. Individuals whose false reactive results occurred before the donor re-entry program started can participate by contacting Canadian Blood Services.

Figure 6 shows the number of eligible donors who were tested and who donated through the donor re-entry program since its inception. Since the beginning of the program in 2014, nearly 4,000 donors have successfully returned to donate, contributing a total of more than 40,000 donations (see Figures 6 and 7). 

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Prior to donating blood, all donors are informed that their blood will be tested for markers of infectious disease, that any abnormal results will be communicated to them, and that public health authorities will be informed of confirmed positive test results, as required by law. At Canadian Blood Services, all donors with positive confirmatory results for any infectious disease marker are notified by letter of their result, and sometimes also by phone call. The impact of notifying donors was evaluated in 2024 based on post-notification interviews with donors who tested positive for HBV, HCV, HTLV and syphilis between 2006 and 2022. As shown in Figure 8, most donors were aware that they had a positive test. Most said they were surprised by the result, and some said they were sad and disappointed. Many also sought medical care. Fewer said they had been contacted by public health, but this may be related to variable public health follow-up approaches across jurisdictions, and possibly donors not always recognizing the follow-up was from public health. Also, HTLV is not a notifiable infection in all jurisdictions.

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Horizon scanning

A horizon scan of potential blood borne infections (e.g., Mpox (monkeypox), tick-borne pathogens) and agents that can negatively impact donor health or the ability to collect blood products (e.g., avian influenza) in the general community ensures rapid revision of donor policies to maintain safety. Even before a new infectious disease is reported in Canada, Canadian Blood Services is aware of emerging infectious agents by monitoring outbreaks in other parts of the world. To ensure that potential risks are identified, Canadian Blood Services needs to be connected with the latest infectious disease, public health and microbiology information at all times. Canadian Blood Services’ medical and scientific staff participate in public health and infectious disease professional organizations and monitor web sites and journals where new information is posted. When appropriate, the Alliance of Blood Operators (ABO) Risk Based Decision Making Framework can be used to facilitate policy decision making. This ensures that relevant assessments including infectious risk to recipients, operational impact of strategies, stakeholder input and health economics are considered. A range of infectious agents that could emerge as a threat within Canada are being monitored. This work began to be systematically rolled into the functions of the new SDL. In late 2024, discussions with the BlueDot group from Toronto began in order to address changes in the information landscape for safety and sufficiency threats to the blood supply. Additionally, current testing and donor deferral policies are re-evaluated to see if they remain appropriate or are resulting in unnecessary donor deferrals without enhancing safety. 

Active laboratory surveillance: Babesiosis

Babesiosis comes from the bite of the black-legged tick (Ixodes scapularis) which can transmit the parasite B. microti. Usually it causes mild flu-like symptoms, and many people are not even aware that they have had it. However, it can also be transmitted by blood transfusion, and infection in blood recipients can result in severe illness or death. To date babesiosis cases in the general population have been reported mainly in the Northeastern and Upper Midwest parts of the United States where more than 1,500 cases per year are reported. Cumulatively more than 200 infections in the United States are believed to have been acquired from a transfusion. In Canada, there has only ever been one case of transfusion transmitted babesiosis in 1998 from a donor who had travelled to the Northeast U.S. In Canada, the parasite is found in small numbers of ticks. A 2013 study at Canadian Blood Services and Héma-Québec tested 13,993 blood donations and none were positive. In 2013 one non-donor infected from a tick bite in Canada was reported, the first case acquired in Canada. A donor study was carried out in 2018 involving more donors. One of 50,752 samples tested from southerly areas across Canada was positive by B. microti nucleic acid testing (NAT), donated in Manitoba and indicating an active infection, and of 14,758 samples tested for antibody to B. microti, four in Southwestern Ontario were positive (but negative by NAT, indicating likely resolved infection at some time in the past). The 2018 rates of Babesia in blood donors is several logs lower than the regions in the U.S. which are mandated by the U.S. Food and Drug Administration to test blood donations for Babesia NAT. The estimated risk of a clinically relevant infection being transmitted from a blood transfusion in Canada is very low at 0.08 per year (0 – 0.38) per year, or about 1 in 12.5 years. In recent years small numbers of human cases have been reported in Manitoba, Ontario, Quebec and the Maritimes. The ABO Risk Based Decision Making Framework was used to evaluate possible risk mitigation strategies. 

Manitoba Babesia surveillance 2024  

Climate change and changing Ixodes tick distributions have led to concerns that the epidemiology of Babesia infections in Canadian blood donors is changing quickly. From July 11 to Nov. 9, 2024, blood samples from Manitoba blood donations were tested for Babesia NAT at the Canadian Blood Services SDL in Ottawa, Ontario. Of 14,027 whole blood donations 13,639 (97 per cent) were tested using Babesia NAT. No donation specimens were positive (see Table 6). The Cadham Provincial Laboratory in Manitoba indicated that the Interlake region is likely the highest risk area for Babesia infection. This vacation region draws visitors from Winnipeg (n= 8,390 donations, 62 per cent of donations tested) and is the region of residence where of donors who donated 1,810 (13 per cent) donations. As part of rotating regional surveillance, samples from Nova Scotia are being tested in 2025. At this time Canadian Blood Services does not recommend routine Babesia donor NAT screening.

Table 6. Summary of Babesia blood donation NAT results from Manitoba: 2024. Babesia testing, Manitoba demographics, removed 69 records with invalid results

^† Based on residential postal code
^‡ RHA – regional health authority
^§ FSA - Forward sortation area
^|| CI – confidence interval

Travel related infections

Donors who travel may return with infections that could be transmitted by blood. Most are only at risk for a period of time after returning until the infection is eliminated from the donor’s bloodstream. Malaria risk is present in parts of the Caribbean, Mexico, Central and South America, Asia, and Africa. Donors are deferred after travel to risk areas for three months, enough time to develop symptoms and self-defer from donation. Former residents of endemic areas are deferred for three years because there is a chance they may be infected for a longer time period without symptoms. Other tropical mosquito-borne infections such as dengue virus have long been present in sunny destinations frequented by Canadians, but in recent years there have been outbreaks of others such as Chikungunya virus and Zika virus not previously seen in the Caribbean, Mexico, Central and South America. Risk to the blood supply was determined to be very low based on quantitative risk assessment. However, to address future travel risks, since 2016 Canadian Blood Services defers all donors who have travelled anywhere outside of Canada, continental U.S., Hawaii, or continental Europe for three weeks after travel. 

Variant Creutzfeldt-Jakob disease (vCJD)

Variant Creutzfeldt-Jakob disease (vCJD) is caused by eating infected beef (Bovine Spongiform Encephalopathy, BSE). Cattle were infected with BSE in the 1980’s in the United Kingdom and later in other parts of Europe but BSE was eradicated from cattle between 1996 and 2001. Because vCJD can be transmitted by transfusion, Canada and many other countries implemented deferrals for spending time in a risk country when there was infected beef. There were only five cases of transfusion transmitted vCJD ever reported (none in Canada). Risk assessment showed that the risk of transfusion transmission was less than one in 16 million without the deferral. The deferral was removed for time spent in most formerly risk countries on February 2021, and for the rest (United Kingdom, Ireland and France) in November 2023. Donors who had been previously deferred for vCJD risk were invited to return by email and telephone, plus there was wider general marketing to increase awareness.   

As shown in Table 7 over 66,000 donors were deferred from 1999 to 2023, and over 13,000 returned to donate after lifting the deferral. The return rate was highest in donors who were more recently deferred. In addition, 8,667 donors who came to donate for the first time told staff (when asked) it was because of the deferral change.

Table 7. Donors deferred for vCJD risk who returned to donate from Nov. 22, 2023 to Nov. 21, 2024.

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Bacteria in blood products usually come from the skin of donors during their blood donation, although occasionally they may come from the donor’s bloodstream. The number of bacteria is usually very low, but because platelet products are stored at room temperature, bacteria can multiply to reach high numbers and then pose a serious risk to the recipient. Until December 2021, Canadian Blood Services tested 100 per cent of apheresis and pooled platelet products for bacteria using the automated BACT/ALERT culture system. In January 2022, Canadian Blood Services started a phase-in implementation of pathogen reduction of platelet products using the INTERCEPT technology, which inactivates bacteria that may be present. As of December 2023, all whole blood derived buffy coat pooled platelets were treated with INTERCEPT, and in May 2024 pathogen reduction of apheresis platelets was fully implemented. Non-pathogen reduced platelets are distributed on rare occasions for clinical contra-indications to pathogen reduction additives. In 2024, no platelet pools were screened for bacterial contamination as all were treated with INTERCEPT. From January to May 2024, 3,492 apheresis platelet units were tested, of which 27 had initial positive results for bacterial growth in the culture bottles. From these, two cultures were confirmed as true bacterial contaminations. In addition, two apheresis platelet products with initial positive results were not confirmed as they were issued and/or transfused. This represents four products in total (11.5 per 10,000) with a chance of bacterial contamination with BACT/ALERT testing, including both true and suspected positives. 

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All cases of potential transfusion transmission of infections are investigated. The Lookback/Traceback Program is notified when a donor tests positive for a transmissible infection, or if the donor reports a transfusion transmissible infection after donating (even if it is not one that would normally be tested for). A lookback investigation is initiated when previous or historical donations are identified as positive for an infection and hospitals are asked to contact the recipients of these donations to arrange testing. A traceback is initiated when a recipient is found to have a transmissible infection and transfusion was confirmed and it is queried as to whether their infection could have been from their blood transfusion. Hospitals provide a list of all blood products that the recipient received, and Canadian Blood Services attempts to contact the donors of these products to arrange testing unless current test results are available.

In 2024, there were 18 lookback cases that required investigation (nine HCV, one HIV, five HBV, two WNV, one malaria). Nine of these were from donors who had a positive transmissible disease marker testing on donation and nine were from external testing or public health notification. Of these, sixteen cases were closed. The remaining two cases were still open at the end of 2024. There were three cases from the previous year closed in 2024. No closed cases were associated with transfusion transmission. 
There were nine traceback cases that required investigation received from external sources in 2024 (six HCV, two HBV, one HIV). Of these, six cases were closed and three remained open at the end of 2024. There was one case from the previous year that closed in 2024. No closed cases were associated with transfusion transmission.  

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Blood stem cells can multiply to renew themselves; the new cells develop into blood cells such as red cells, white cells, and platelets. In adults, they are found mainly in the marrow of large bones, with a few cells in the bloodstream. The cord blood of newborn babies, taken from the umbilical cord and placenta after the delivery of a healthy baby, is also very rich in stem cells. Blood stem cells can therefore be obtained from the bone marrow, from circulating blood (called peripheral blood stem cells) or from the umbilical cord (cord blood) after a baby is born. Blood stem cells are very important in treating various diseases such as leukemia, lymphoma, and multiple myeloma. Canadian Blood Services has a coordinated national stem cell program which includes adult registrants and banked cord blood units. Infectious disease testing for all stem cell products includes the same markers tested for whole blood donations.  

Canadian Blood Services Stem Cell Registry  

Canadian Blood Services Stem Cell Registry is a registry of Canadians who have volunteered to donate either bone marrow or peripheral blood stem cells should a recipient need it at some time in the future. Potential registrants complete a questionnaire which includes risk factors for transmissible infections and are tested for their Human Leukocyte Antigen (HLA) profile. In 2024, there were about 458,000 registrants in the registry. In total, 495 registrants were identified as potential matches for recipients and had additional testing. There were no infectious disease positive results.

Canadian Blood Services’ Cord Blood Bank

Canadian Blood Services’ Cord Blood Bank collected cord blood at four sites in Canada in 2024 (Ottawa, Brampton, Edmonton, and Vancouver). Participating mothers at these hospitals who volunteer to donate their baby’s cord blood complete a questionnaire about medical conditions that could be passed on to a recipient, as well as risk factors for transmissible infections. If the donation is suitable for transplantation (i.e., has enough stem cells) with negative results for all infections, the cells are frozen and stored until a recipient needs them. In 2024, there were 290 blood samples from mothers tested, there were no infectious disease positive results

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In the 1980’s men who had sex with another man, even once since 1977, were not eligible to donate blood to reduce the risk of HIV transmission. With much improved donor testing and surveillance for emerging and re-emerging pathogens, the deferral period has been gradually reduced, moving to five years in 2013, to one year in 2016, and to three months in 2019. HIV rates did not increase following any of these changes. Anonymous donor compliance surveys showed that shortening the deferral period allowed more gay, bisexual, and other men who have sex with men to donate blood and donor compliance was not adversely affected. With the three month deferral in place, the risk of releasing an HIV infectious unit for transfusion was very low at one in 19.9 million donations (95 per cent CI one in 2.7 million – one in 1,668 million). 

Many countries have switched from lifetime to shorter time deferrals, and recently a number of countries have removed their time-based deferrals in favour of individual behaviour-based screening. The UK removed their time-based deferral in 2021, France removed their time-based deferral in 2022, the Netherlands in 2023, all with different risk reducing donor eligibility criteria. The U.S. also removed their time-based deferral in 2023 and implemented behaviour-based screening. 

On Sept. 11, 2022, Canadian Blood Services removed the three month deferral for men having had sex with another man and implemented two sexual behaviour-based screening questions that all donors must answer irrespective of sexual orientation or gender (see Figure 9). Additionally, since all donors are asked the same sexual risk questions, trans donors, whose gender identity is different than their sex determined at birth, can register and complete the questionnaire in their affirmed gender. As of Dec. 31 2024, 0.10 per cent of donors presenting to donate were temporarily deferred based on these sexual risks (see Figure 9). Deferred donors tended to be younger and were slightly more likely to be males than females. There were seven allogeneic blood donations that tested positive for HIV during this period, and one source plasma donation. A longer observation period is necessary to see if there has been any change in HIV rates.

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Donor compliance with sexual behaviour-based screening

Anonymous online donor surveys to assess the percentage of donors who had anal sex with a new or more than one partner before the deferral change (when most were eligible) and after when all should have been deferred were carried out. Before implementing 13,159 donors completed the survey (33 per cent of those invited) and after implementation 11,217 donors completed the survey (28 per cent of those invited). Data were weighted to reflect the age, sex and donation status of the donor base. Before implementing (when most were eligible) 0.86 per cent of donors and after (when all should have been deferred) 0.76 per cent (p>0.05) said they had anal sex with a new or more than one partner in the last three months. Thus 87 per cent of donors who had anal sex with a new or more than one partner in the last three months were non-compliant after the deferral was implemented. This may suggest that many donors make a judgement about their risk when deciding to disclose, since nearly all were eligible before the deferral and the blood supply was safe.

Testing for HIV Pre-exposure Prophylaxis medications (PrEP)

All donors are asked if they have taken oral PrEP in the last four months and deferred if they have (two years for injectable PrEP). Samples from people infected with HIV while taking PrEP may test negative for a longer time than for those not taking PrEP which could increase the chance of an infection being missed by donor testing. After implementing the new deferral, left-over blood samples from first time male donors in Toronto and Vancouver, donors who tested positive for syphilis, donors who had been deferred for PrEP use at some point in the past, and donors who tested positive for HIV were tested for PrEP medications (tenofovir and emtricitabine). Testing was carried out at the B.C. Center for Excellence in HIV/AIDS. No donations positive for PrEP from first time male donors or HIV positive donors were identified, but 2.3 per cent of syphilis positive and 12.2 per cent of donors previously deferred for oral PrEP use tested positive for PrEP (see Figure 10). Tenofovir and emtricitabine (PrEP) have a half-life of about three to four days, indicating that those who tested positive for PrEP have taken PrEP very recently and failed to disclose this in pre-donation screening.

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Canadian Blood Services takes many precautions to make sure that giving blood is safe for donors. These include a health screening questionnaire and a hemoglobin fingerstick screen, as well as providing water and a salty snack pre-donation, refreshments post-donation, and monitoring the donor for adverse reactions during and after donation. Most donors do not have any problems during or after their donation, but it is important to keep track of any incidents that happen so that donor care can be improved. Definitions of reactions are shown in Table 8. 

Table 8. Reaction and definitions.

Reaction rates per 10,000 whole blood donations in 2024 are shown in Figure 11 with those in 2023 for comparison. Moderate vasovagal reactions were significantly elevated (p<0.01) while severe vasovagal reactions were not significantly different (p>0.05). As there were no operational changes and other unrelated reactions such as bruises were increased, this may reflect a change in reporting. People more likely to experience a reaction are first time donors, young donors (17-25 years old), and female donors. The reaction reporting system is oriented towards capturing moderate and severe reactions. Most reactions are mild, such as feeling faint or bruising at the needle site, but these are only recorded if mentioned by the donor at some point after donation. A further breakdown of fainting reactions (both moderate and severe) in whole blood donors, by sex and donation history, is provided in Table 9. Injuries were generally not severe such as bruises and cuts from falling. Two donors had loose/chipped teeth and one donor had a fractured ankle.

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Table 9. Fainting (vasovagal) reactions (per 10,000 collections) in 2024.

^† All comparisons (male vs female, first time vs repeat) are statistically significant among moderate & severe reactions combined (p<0.01). For reactions associated with injury, all were significant (p<0.05), except for male first time and female first time donors (p>0.05). 

Pre-donation water and salty snacks were put in place in 2019 to reduce vasovagal (faint) reactions. Donor instructions to carry out muscle tension exercises while donating continued to be provided. These can also reduce the risk of a vasovagal reaction. Collectively the pre-donation water and salty snacks, and muscle tension exercises were part of the donor wellness initiative. During the pandemic, collection sites provided post-donation refreshments as always but asked donors to have them outside of the clinic. Collection sites stopped providing salty snacks and water before donating, although donors were encouraged to have their own before coming to the clinic. Between May and June 2022, collection sites increased the distribution of pre-donation salty snack and water. Figure 12 shows the reaction rates before putting in place the donor wellness activities, while they were in place, after stopping the pre-donation water and salty snacks, and during the time donor wellness activities were resumed. Initially there was a downward trend in vasovagal reactions for all groups associated with donor wellness activities.  After taking into account gender and donation status, the vasovagal reaction rates were lower during the wellness activities and initially after the water and salty snacks were stopped but later increased. After the wellness activities resumed, the rates returned to the pre-donor wellness level. The uptake of wellness activities once resumed may have been less than when first implemented.

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Donor hemoglobin and iron

The most common reason for donor deferral at collection sites is a failed hemoglobin fingerstick screen, which indicates the hemoglobin level is below the acceptable range for donation. Low hemoglobin is often related to low iron stores, as iron is essential for the production of hemoglobin (the protein responsible for carrying oxygen in red blood cells).

Research conducted by Canadian Blood Services has shown that iron stores tend to be lower in females compared to males. Additionally, frequent blood donation further reduces iron stores in both genders. To mitigate the risk of donors developing iron deficiency anemia, Canadian Blood Services has established specific minimum hemoglobin thresholds for donors: 130 g/L for males and 125 g/L for females. For plasma donors, the required minimum hemoglobin level to enable donation is 125 g/L, regardless of gender.

Due to the impact of frequent donations on iron levels, Canadian Blood Services also requires a minimum wait time between whole blood donations. While the interval is 56 days for males, it was extended from 56 to 84 days for females in 2017. This extended inter-donation period provides females with additional time to replenish their iron stores and restore their hemoglobin levels to baseline.

By implementing these measures, Canadian Blood Services aims to ensure the health and safety of donors while maintaining a reliable supply of blood and plasma. Information about iron and the safety of blood donation can be found at www.blood.ca as well as in the ‘What you must know to give blood’ pamphlet provided to all donors prior to every donation.

In 2024, the median hemoglobin levels among whole blood donors were 151 g/L for males and 137 g/L for females. Among male first-time donors, the median hemoglobin level was 155 g/L compared to 151 g/L among male repeat donors. For female donors, the median hemoglobin level was consistently 137 g/L for both first-time and repeat donors. Hemoglobin deferral rates were notably higher among females in first-time (9.4 per cent) and repeat donations (7.9 per cent) compared to males in first-time (1.0 per cent) and repeat donations (1.8 per cent) (see Figure 13).

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Ferritin testing

Measuring plasma ferritin levels can provide an early indication of low iron stores before hemoglobin levels drop. Females are more likely than males to have low iron stores prior to donating, making iron loss due to frequent donation more common among females.

On Jan. 16, 2023, Canadian Blood Services implemented ferritin testing for every 10th donation made by females. Donors with low ferritin levels were informed of their results and advised to refrain from donating for at least six months. They were also encouraged to consult their health care provider for further testing and potential iron supplementation. Donors were not deferred based on ferritin test results.

As illustrated in Figure 14, nearly a quarter of females making their 10^th, 20^th or 30^th etc., donation had low ferritin. Among these donors, over 30 percent had donated six times or more in the previous two years.

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Despite being advised to wait at least six months before donating again, 35 per cent of low ferritin donors returned within five months. Overall, 75 per cent of low ferritin donors returned to donate within 18 months, compared to 86 per cent of donors with normal or high ferritin donors (see Figure 15). Deferral rates decreased with increasing time to return visit. By implementing ferritin testing and providing appropriate guidance to donors, Canadian Blood Services aims to better manage donor iron stores, ensuring the health and safety of donors while maintaining a reliable blood supply. Further monitoring is required to evaluate the impact of the policy on donation return and frequency.

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The demographic characteristics of whole blood donors are described in Figures 16 to 19 and Table 10. By region, the distribution of donors ranged from 9.8 per cent in the Prairie provinces to 44.7 per cent in Ontario. The majority of these were repeat donors (79 per cent) who donated 90 per cent of donations and roughly half across all regions were females (48 per cent). The demographics of source plasma donors can be found in Section 3. All donors are invited to respond to a voluntary question about their race/ethnic group, which assists the laboratory in selecting donor samples for additional typing for rare blood groups that are more frequent in certain populations. Over 95 per cent of donors had answered this question.

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Table 10. Percentage of blood donors by sex and region.  

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As in previous years, most donations overall were given by donors who self-identify as white (74.1 per cent). As shown in Figure 17, the proportion of racialized donors varied by region, ranging from 11 per cent in the Atlantic region to 33 percent in British Columbia. The proportion of racialized donors increased slightly in 2024 compared with 2023 and 2022 across all Canadian regions.

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While first time blood donors make up 22 per cent of whole blood donors overall, 39 per cent are from a racialized group (see Figure 18). This is in part related to increasing diversity in younger age groups. Starting in 2023, donors were able to choose from a more comprehensive list to describe their respective backgrounds than in previous years. Of the 25.9 per cent of donors who selected a non-white background, donors self-identifying as Asian constituted the second largest group of blood donors across all regions (12.3 per cent of all donors providing information) (Figure 19). This was followed by multi-ethnic donors (3.8 per cent) and Filipino donors (2.6 per cent). Hispanic/Latino donors constituted 1.8 per cent, Arab donors constituted 1.6 per cent and Indigenous donors (First Nations/Metis/Inuit) constituted 1.5 per cent of the total donor base, and Black donors 0.8 per cent. Percentages of donors in ethnic groups are similar to their representation in the general population, with the exception of under-representation of Black and Indigenous groups. In the Canadian population approximately 5 per cent are Indigenous and 4.3 per cent Black.

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Donor screening 

Vesnaver E, Goldman M, O’Brien SF MacPherson P, Butler-Foster T, Lapierre D, Otis J, Devine DV, Germain M, Rosser A, et al. Barriers and enablers to source plasma donation by gay, bisexual and other men who have sex with men under revised eligibility criteria: protocol for a multiple stakeholder feasibility study.  Health Res Policy Sys 2021;18:131.  

O’Brien SF, Goldman M, Robillard P, Osmond L, Myhal G, Roy E.  Donor screening question alternatives to men who have sex with men time deferral: Potential impact on donor deferral and discomfort.  Transfusion 2021;61:94-101. 

Caffrey N, Goldman M, Osmond L, Yi QL, Fan W, O’Brien SF. HIV incidence and compliance with deferral criteria over three progressively shorter time deferrals for men who have sex with men in Canada. Transfusion 2022;62:125-134. 

Caffrey N, Goldman M, Lewin A, Osmond L, O’Brien SF. Behaviour-based screening questions and potential donation loss using the “for the assessment of individualized risk” screening criteria: A Canadian perspective. Transfus Med 2022;32:422-427. 

Goldman M, Uzicanin S, O’Brien SF. Has the switch to sexual behaviour screening impacted deferrals for pre- and post-exposure prophylaxis therapy for human immunodeficiency virus? Vox Sang 2025 Online ahead of print.  

Germain M, Gregoire Y, Custer BS, Goldman M, et al. An international comparison of HIV prevalence and incidence in blood donor and general population: a BEST Collaborative study. Vox Sang 2021;61:2530-2537. 

Goldman M. How do I think about blood donor eligibility criteria for medical conditions? Transfusion 2021;61:2530-2537. 

Miller O, Caffrey N, O’Brien SF, Goldman M. Evolving policies for donors with diabetes: The Canadian experience. Vox Sang 2022;117:1415-1419. 

Quee F, SF O’Brien, Prinsze et al.  Whole blood donor return rates after deferral for tattooing of body piercing-Survey across blood donation services: the BEST collaborative study. Vox Sang 2022;117:1085-1089. 

Jacquot C, Tiberghien P, van den Hurk K, Ziman A, Shaz B, Apelseth TO, Goldman M, The BEST Collaborative.  Blood donor eligibility for medical conditions: A BEST collaborative study.  Vox Sang 2022;117:929-936. 

Holloway K, Campbell C, Ali R, et al. A critical contribution in a time of crisis: Examining motivations and deterrents to COVID-19 convalescent plasma donation and future donation intentions among prospective Canadian donors. Transfusion Medicine, 2022;32:351-365. 

Etherington C, Palumbo A, Holloway K, et al. Barriers and enablers to and strategies for promoting domestic plasma donation throughout the world: Overarching protocol for three systematic reviews. PLoS ONE 2023;18: e0296104.  

Berger, M, Easterbrook, A, Holloway, K, et al. What influences decisions to donate plasma? A rapid review of the literature. Vox Sanguinis, 2023;118: 817-824.  

Caffrey N, O’Brien SF, Walsh GM, Haw J, Goldman M. Evolving the gay, bisexual and other men who have sex with men time-based deferral to sexual screening for all donors: The contribution of Canadian research programmes. Vox Sang 2023;118:605-615. 

Fisher W A, Kohut T, Woo H, & Haw J. Alternatives to blood donor deferral of gay, bisexual, and other men who have sex with men: Acceptability of screening the sexual risk behavior of all blood donors. Transfusion 2023;63:531–540. 

Vesnaver E, Gibson E, Goldman M et al. Navigating imperfect policies to donate plasma: Survey on plasma donation and a pilot plasma donation program among men who have sex with men in Canada. Transfusion 2023;63:1172-1183.  

Goldman M, Lewin A, Renaud C, O’Brien SF. Implementation of sexual risk behavior donor screening in Canada. Transfusion 2024;64:1254-1261. 

O’Brien SF, Naicker K, Osmond L, Holloway K, Drews SJ, Bigham M, Goldman M. Notification of blood donors who test positive for transfusion-transmissible infections. Vox Sang 2024 online ahead of print 

Residual Risk 

O’Brien SF, Gregoire Y, Pillonel J, Steele WR, Custer B, Davison K, Germain M, Lewin A, Seed CR.  HIV residual risk in Canada under a three-month deferral for men who have sex with men.  Vox Sang 2020;115:133-139.  

Caffrey N, Goldman M, Lewin A, Gregoire Y, Yi QL, O’Brien SF. Removing the men who have sex with men blood donation deferral: Informing risk models using Canadian public health surveillance data. Transfus Clin Biol 2022;29:198-204. 

Babesia microti 

O’Brien SF, Drews SJ, Yi QL, Bloch EM, Ogden NH, Koffi JK, Lindsay LR, Gregoire Y, Delage G. Risk of transfusion-transmitted Babesia microti in Canada. Transfusion 2021;61:2958-2968.   

Drews SJ, Van Caeseele P, Bullard J, Lindsay LR, Gaziano T, Zeller MP, Lane D, Ndao M, Allen VG, Boggild AK, O’Brien SF, Marko D, Musuka C, Almiski M, Bigham M. Babesia microti in a Canadian blood donor and lookback in a red blood cell recipient. Vox Sang 2022;117:438-441. 

Drews SJ, Kjemtrup AM, Krause PJ, Lambert G, Leiby DA, Lewin A, O’Brien SF, Renaud C, Tonnetti L, Bloch EM. Transfusion-transmitted Babesia spp: A changing landscape of epidemiology, regulation, and risk mitigation. J Clin Microbiol 2023;61:e0126822. 

Hepatitis E 

Fearon MA, O’Brien SF, Delage G, Scalia V, Bernier F, Bigham M, Weger S, Prabhu S, Andonov A.  Hepatitis E in Canadian blood donors.  Transfusion 2017;57:1420-1425. 

Delage G, Fearon M, Gregoire Y, Hogema BM, Custer B, Scalia V, Hawes G, Bernier F, Nguyen ML, Stramer S. Hepatitis E virus infection in blood donors and risks to patients in the United States and Canada. Trans Med Rev 2019;33:139-145. 

Hepatitis B 

O’Brien SF, Reedman CN, Osiowy C, Bolotin S, Yi QL, Lourenco L, Lewin A, Binka M, Caffrey N, Drews SJ. Hepatitis B blood donor screening data: An under-recognized resource for Canadian public health surveillance. Viruses 2023;15:409 

O’Brien SF, Ehsani-Moghaddam B, Goldman M, Drews SJ. Prevalence of hepatitis B in Canadian first time blood donors: Association with social determinants of health. Viruses 2024;16:117 

Osiowy C, Giles E, Lowe CF, Matic N, Murphy DG, Uzicanin S, Drews SJ, O’Brien SF. Hepatitis B virus genotype surveillance in Canadian blood donors and a referred patient population, 2016-2021. Vox Sang 2024;119:232-241.  

Hepatitis C  

O’Brien SF, Ehsani-Moghaddam B, Osmond L, Fan W, Goldman M, Drews SJ.  Epidemiology of hepatitis C over 28 years of monitoring Canadian blood donors: Insight into a low-risk undiagnosed population.  BMC Public Health 2024; 24:2319. 

Bacteria 

Ramirez-Arcos S, Evand S, McIntyre T, Pang C, Yi QL, DiFranco C, Goldman M. Extension of platelet shelf life with an improved bacterial testing algorithm. Transfusion 2020;60:2918-2928. 

Malaria 

O’Brien SF, Ward S, Gallian P, Fabra C, Pillonel J, Davison K, Seed CR, Delage G, Steele WR, Leiby DA   Malaria blood safety policy in five non-endemic countries: a retrospective comparison through the lens of the ABO risk-based decision-making framework.  Blood Transfus 2019;17:94-102. 

HTLV 

O’Brien SF, Yi QL, Goldman M, Gregoire Y, Delage G.  Human T-cell lymphotropic virus: A simulation model to estimate residual risk with universal leukoreduction and testing strategies in Canada.  Vox Sang 2018;113:750-759. 

O’Brien SF, Ehsani-Moghaddam B, Goldman M, Osmond L, Fan W, Drews SJ.  Prevalence of human T-cell lymphotropic virus-1/2 in Canada over 33 years: A unique contribution of blood donors to public health surveillance.  Can J Public Health 2024;115:611-621. 

Syphilis 

O’Brien SF, Drews SJ, Yi QL, Osmond L, Tran V, Zhou HY, Goldman M.  Monitoring syphilis serology in blood donors: Is there utility as a surrogate marker of early transfusion transmissible infection behavioral risk?  Transfusion 2023;63:1195-1203. 

Iron deficiency 

Goldman M, Uzicanin S, Osmond L, Yi QL, Scalia V, O’Brien SF. Two year follow-up of donors in a large national study of ferritin testing.  Transfusion 2018;25:2868-2873. 

Goldman M, Yi QL, Steed T, O’Brien SF.  Changes in minimum hemoglobin and interdonation interval: impact on donor hemoglobin and donation frequency.  Transfusion 2019;59:1734-1741. 

Chasse M, Tinmouth A, Goldman M et al.  Evaluating the clinical effect of female donors of child-bearing age on maternal and neonatal outcomes: A cohort study.  Transfusion Medicine Reviews, 2020;24:117-123. 

Blake JT, O’Brien SF, Goldman M. The impact of ferritin testing on blood availability in Canada. Vox Sang 2022;117:17-26. 

Donor wellness 

Goldman M, Germain M, Gregoire Y, Vassallo RR, Kamel H, Bravo M, O’Brien SF.  Safety of blood donation by individuals over age 70 and their contribution to the blood supply in five developed countries:  a BEST Collaborative group study.  Transfusion 2019; 59:1267-1272. 

Goldman M, Uzicanin S, Marquis-Boyle L, O’Brien SF. Implementation of measures to reduce vasovagal reactions: Donor participation and results. Transfusion 2021;61:1764-1771. 

Public health 

O’Brien SF, Drews SJ, Lewin A, Russell A, Davison K, Goldman M. How do we decide how representative our donors are for public health surveillance? Transfusion 2022;62:2431-2437. 

O’Brien SF, Drews SJ, Lewin A, Osiowy C, Drebot MA, Renaud C. Canadian blood suppliers: An expanded role in public health surveillance? Can Comm Dis Rep 2022;48:124-130. 

O’Brien SF, Goldman M, Drews SJ. An expanded role for blood donor emerging pathogen surveillance CMAJ 2023;195:E16. 

Climate change and infectious risks 

Drews SJ, Wendel S, Leiby DA, Tonnetti L, Ushiro-Lumb I, O’Brien SF Climate change and parasitic risk to the blood supply. Transfusion 2023;63:638-645. 

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Implementation dates of testing

^†These are the dates that testing for the marker began. Tests have been upgraded as new versions as the test became available. 
^‡Pathogen reduction technology implemented for random donor platelets in 2022/2023, and apheresis platelets in 2024, hence bacterial testing no longer required. 

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