SARS-CoV-2 immunoassays in a predominantly vaccinated population: Performances and qualitative agreements obtained with two analytical approaches and four immunoassays.

BACKGROUND AND OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurveys are typically analysed by applying a fixed threshold for seropositivity ('conventional approach'). However, this approach underestimates the seroprevalence of anti-nucleocapsid (N) in vaccinated individuals-who often exhibit a difficult-to-detect anti-N response. This limitation is compounded by delays between the onset of infection and sample collection. To address this issue, we compared the performance of four immunoassays using a new analytical approach ('ratio-based approach'), which determines seropositivity based on an increase in anti-N levels. MATERIALS AND METHODS: Two groups of plasma donors and four immunoassays (Elecsys total anti-N, VITROS total anti-N, Architect anti-N Immunoglobulin G (IgG) and in-house total anti-N) were evaluated. First-group donors (N = 145) had one positive SARS-CoV-2 polymerase chain reaction (PCR) test result and had made two plasma donations, including one before and one after the PCR test (median = 27 days post-PCR). Second-group donors (N = 100) had made two plasma donations early in the Omicron wave. RESULTS: Among first-group donors (97.9% vaccinated), sensitivity estimates ranged from 60.0% to 89.0% with the conventional approach, compared with 94.5% to 98.6% with the ratio-based approach. Among second-group donors, Fleiss's κ ranged from 0.56 to 0.83 with the conventional approach, compared with 0.90 to 1.00 with the ratio-based approach. CONCLUSION: With the conventional approach, the sensitivity of four immunoassays-measured in a predominantly vaccinated population based on samples collected ~1 month after a positive test result-fell below regulatory agencies requirement of ≥95%. The ratio-based approach significantly improved the sensitivities and qualitative agreement among immunoassays, to the point where all would meet this requirement.

Cost-effectiveness of pathogen reduction technology for plasma and platelets in Québec: A focus on potential emerging pathogens.

BACKGROUND: The last economic evaluation of pathogen reduction technology (PRT) in Canada was conducted in 2007. We reassessed the cost-effectiveness of PRT in the province of Québec (which has its own blood supplier) and included an evaluation of the potential impact of emerging pathogens on cost-effectiveness. STUDY DESIGN AND METHODS: Decision analytic Markov models were developed to simulate the costs and quality-adjusted life-years (QALY) associated with PRT as an addition to existing safety measures for plasma and platelet products (except for bacterial culture). Models accounted for several infectious and noninfectious transfusion reactions, recipients' productivity losses ensuing from these reactions, and the impact of PRT on platelet function. Scenario analyses were conducted to evaluate the impact of a new highly contagious human immunodeficiency virus (HIV)-like or West Nile virus (WNV)-like pathogen, assuming various epidemiological scenarios. RESULTS: In the base case, the incremental cost-effectiveness ratio (ICER) of PRT was estimated at $8,088,974/QALY gained. Assuming the presence of an HIV-like pathogen, the ICER was $265,209/QALY gained in the "average transmission" scenario, $1,274,445/QALY gained in the "rapid testing scenario," and $123,063/QALY gained in the "highly contagious" scenario. Assuming the presence of a WNV-like pathogen, the ICER was $7,469,167/QALY gained in the "average transmission" scenario and $6,652,769/QALY gained in the "highly contagious" scenario. CONCLUSION: The cost-effectiveness of PRT may substantially improve in the event of a new, blood-borne pathogen. Given their significant impact on cost-effectiveness, the emergence of new pathogens should be considered when deciding whether to adopt PRT.

Balancing non-discriminatory donor selection and blood safety in the Netherlands: Evaluation of an individual risk assessment of sexual behavior.

BACKGROUND: To better balance the safety of the blood supply and the inclusion of men who have sex with men (MSM), further improvements are needed to the risk management strategy employed in the Netherlands to reduce transfusion-transmissible infections (TTIs). A gender-neutral individual risk assessment could provide a solution by determining donor eligibility based on sexual behaviors known to increase the risk of TTIs. Our objective is to estimate the proportion of blood donors that would be deferred by such an assessment, as well as their discomfort answering such questions. STUDY DESIGN AND METHODS: Two surveys were distributed in May 2020 to assess sexual behavior in blood donors in the last 4, 6, and 12 months, as well as their discomfort reporting such information. A combination of both surveys measured the extent to which discomfort was associated with reporting sexual behavior. A high-risk sexual behavior pattern was defined as having had multiple sexual partners and having engaged in anal sex, without consistent condom use. RESULTS: Of all 2177 participating whole blood donors, 0.8% report engaging in high-risk sexual behaviors over the last 4 months and would therefore be ineligible to donate. When accounting for the additional proportion of donors that reported such questions would stop them from donating, 2.0% and 3.2% of female and male donors, respectively, would be lost. DISCUSSION: Gender-neutral eligibility criteria based on high-risk sexual behaviors may reduce the overall number of eligible donors in the Netherlands, but could make blood donation more accessible to a broader group of donors.

Reported non-compliance with pre-donation screening among blood donors in Québec, Canada: A focus on the 3-month deferral for men who have sex with men.

BACKGROUND AND OBJECTIVES: In Québec (Canada), the donation deferral for men who have sex with men (MSM) has recently been shortened to 3 months. Whether this change impacted compliance with pre-donation screening is unknown. We assessed compliance with the disclosure of male-to-male sex and other behavioural risk factors for HIV amid this change. MATERIALS AND METHODS: Québec residents who donated from 14 July 2020 to 30 November 2020 were invited to participate in an online survey. Donors were informed that the survey was optional and anonymous. Survey questions were those used for routine pre-donation screening. Rates of reported non-compliance were weighted based on several characteristics. RESULTS: Of 21,918 contacted donors, 7113 (32.45%) participated. Among male participants (N = 3347), six (0.27% [95% confidence interval (CI) = 0.09%-0.44%]) were not compliant with a 3-month MSM deferral. Among female participants (N = 3766), two (0.06% [95% CI = 0.00%-0.13%]) were not compliant with a 3-month deferral for sex with a man who had male-to-male sex ≤12 months. Other risk factors exhibited similar or lower rates of reported non-compliance. CONCLUSION: Reported non-compliance with a 3-month MSM deferral and the disclosure of other HIV behavioural risk factors was low. These results warrant the investigation of behavioural donor risk assessment approaches to further improve the inclusiveness of blood donation.

Risk of transfusion-related acute lung injury and human immunodeficiency virus associated with donations from trans donors in Quebec, Canada.

BACKGROUND AND OBJECTIVES: Blood operator must establish selection criteria according to the populations at risk of blood-related infections and complications. Therefore, this study aimed to assess the risks of transfusion-related acute lung injury (TRALI) and human immunodeficiency virus (HIV) associated with donations from trans persons. MATERIALS AND METHODS: Donor screening data from Héma-Québec were used. The risks of TRALI and HIV were estimated based on internal data and assumptions derived from the literature. The risk was assessed under four scenarios: a most likely scenario, an optimistic scenario and two pessimistic scenarios. All scenarios assumed no prior screening for trans donors. RESULTS: The trans population comprised 134 donors, including 94 (70.1%) trans men. Of the 134 donors, 58 (43.3%) were deferred from donating a blood-derived product because of an ongoing gender-affirming genital surgery, and the remaining 76 (56.7%) were eligible donors. The risk of having a TRALI-causing donation, given that it comes from a trans man, was estimated at one every 115-999 years for all scenarios. The risk of having an HIV-contaminated donation, given that it comes from a trans woman, was estimated at one every 1881-37,600 years for all scenarios. CONCLUSION: This study suggests that donations from trans persons are associated with a negligible risk of TRALI and HIV.

Whole blood donor return rates after deferral for tattooing or body piercing-Survey across blood donation services: The BEST collaborative study.

BACKGROUND AND OBJECTIVES: To protect transfusion recipients from transfusion-transmissible infections, blood donors are deferred from donating after recent tattooing or piercing. To explore to what extent and how this deferral impacts donor availability, we performed an international study to investigate how many donors were deferred for a recent tattoo or piercing and how many of these donors returned to donate. MATERIALS AND METHODS: We surveyed blood centre members of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative and the European Blood Alliance Donor Studies Working Group on their numbers of donations, tattoo and piercing deferrals, and return rates in the year 2017. RESULTS: Eight blood centres participated. Overall, deferral rates were lower for repeat donors compared to new donors. Repeat donors were more likely to return than new donors. Women and young donors were more often deferred than male and older donors. Men were more demotivated by tattoo or piercing deferral, resulting in lower return rates compared to women. Return rates differed greatly between blood centres. CONCLUSION: Tattoo and piercing deferrals lead to missed donations and result in lower return rates. However, the numbers vary largely internationally, probably due to cultural and policy differences. Shortening deferral periods after tattooing or piercing may reduce the impact on donor availability, which should be investigated in single-centre studies.

HIV residual risk in Canada for apheresis source plasma donation without deferral for men who have sex with men.

BACKGROUND AND OBJECTIVES: In Canada, men having sex with men (MSM) are deferred for 3 months from last sexual contact to reduce human immunodeficiency virus (HIV) risk to recipients. The aim of this paper was to model the Canadian residual risk of HIV-positive source plasma incorporating pathogen inactivation (PI) under no MSM deferral scenarios for apheresis plasma donations. MATERIALS AND METHODS: A combined Bayesian network (BN) and Monte Carlo approach were implemented to estimate the HIV residual risk under 3-month deferral compared with no deferral without quarantine scenarios for MSM donors. Models involve the stochastic generation of donation and its infection status based on its corresponding simulated donor profile. Viral load reduction conferred by PI used by source plasma fractionators was simulated. Model parameters were derived from Héma-Québec and Canadian Blood Services data, viral loads in a large sample of HIV-positive US blood donors, CSL Behring documentation and from published data. RESULTS: In the most likely scenario for the 3-month deferral model, there were 2.71 positive donations per 1,000,000 donations (95% confidence interval [CI] 2.63-2.78). For the no-deferral model, there were 3.01 positive donations per 1,000,000 donations (95% CI 2.94-3.09). For both scenarios, the risk of having an infectious pool was 0 in 300,000 pools (95% CI 0-0.0000123) after consideration of PI. CONCLUSION: Based on simulation results, there would be a negligible HIV residual risk associated with the removal of a time-based MSM deferral without quarantine for source plasma incorporating PI.

Risk of transfusion-transmitted Babesia microti in Canada.

BACKGROUND: Babesia microti has gained a foothold in Canada as tick vectors become established in broader geographic areas. B. microti infection is associated with mild or no symptoms in healthy individuals but is transfusion-transmissible and can be fatal in immunocompromised individuals. This is the first estimate of clinically significant transfusion-transmitted babesiosis (TTB) risk in Canada. STUDY DESIGN AND METHODS: The proportion of B. microti-antibody (AB)/nucleic acid amplification test (NAT)-positive whole blood donations was estimated at 5.5% of the proportion of the general population with reported Lyme Disease (also tick-borne) based on US data. Monte Carlo simulation estimated the number and proportion of infectious red cell units for three scenarios: base, localized incidence (risk in Manitoba only), and donor study informed (prevalence from donor data). The model simulated 1,029,800 donations repeated 100,000 times for each. RESULTS: In the base scenario 0.5 (0.01, 1.75), B. microti-NAT-positive donations would be expected per year, with 0.08 (0, 0.38) recipients suffering clinically significant TTB (1 every 12.5 years). In the localized incidence scenario, there were 0.21(0, 0.7) B. microti-NAT-positive donations, with 0.04 (0, 0.14) recipient infections (about 1 every 25 years). In the donor study informed scenario, there were 4.6 (0.3, 15.8) B. microti-NAT-positive donations expected, and 0.81 (0.05, 3.14) clinically significant TTB cases per year. DISCUSSION: The likelihood of clinically relevant TTB is low. Testing would have very little utility in Canada at this time. Ongoing pathogen surveillance in tick vectors is important as B. microti prevalence appears to be slowly increasing in Canada.

An international comparison of HIV prevalence and incidence in blood donors and general population: a BEST Collaborative study.

BACKGROUND AND OBJECTIVES: Efficiency in mitigating HIV transmission risk by transfusion may vary internationally. We compared HIV prevalence and incidence in blood donors across different jurisdictions in relation to those rates in the general population and differences in deferral practices. MATERIALS AND METHODS: Data from 2007 to 2016 were collected in Australia, Brazil (São Paulo), Canada, England, France, Italy, Ireland, Japan, the Netherlands, New Zealand, Norway, Spain (Basque Country), USA (Vitalant) and Wales. For each country/region, the number of HIV antibody-positive donations and nucleic acid testing (NAT)-only-positive donations was broken down according to first-time or repeat donor status, along with the relevant denominators. RESULTS: There is a modest correlation between HIV prevalence among first-time donors and HIV prevalence in the general population. However, rates of HIV-positive donations in repeat donors, a proxy for incidence, do not correlate with incidence rates in the general population. Rates in donors from Italy and Basque Country, where deferral criteria for men having sex with men are less stringent, are higher compared with most other jurisdictions. Rates of NAT-only-positive donations are extremely low and do not differ significantly after adjustment for multiple comparisons. CONCLUSION: Donor HIV rates are only weakly associated with those observed in the general population. Countries with less stringent deferral criteria have higher HIV rates in their donor population, but the rates remain very low.

The impact of age and sex on first-time donor return behavior.

BACKGROUND: This study examined the impact of age and sex of first-time donors who had not experienced an adverse event or deferral on their likelihood of and time to return. STUDY DESIGN AND METHODS: On behalf of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative, international blood collection agencies (BCAs) were invited to provide data on first-time whole blood donors in 2014, including initial presentation date, collection site type, age, sex, blood type, return to donate within 24 months (yes/no), and subsequent presentation date. RESULTS: Eight BCAs contributed 706,789 records. The overall odds of returning to donate were slightly lower in female versus male donors, and the overall age trend was U-shaped with younger and older donors having higher odds for returning relative to middle-aged donors. However, variations by BCA were observed. Specifically, in three BCAs, women had higher odds of returning to donate than men. Further, while across seven BCAs the smallest cohort of older first-time donors returned at a higher rate and returned more quickly than middle-aged first-time donors, the behavior of younger donors varied substantially between BCAs. CONCLUSION: While older first-time donors are more likely to return and return more quickly than middle-aged donors they make up only a small proportion of first-time donors, whereas the larger group of younger donors exhibits less clear patterns of return compared to middle-aged donors. Further research is needed to determine whether targeting the recruitment of older donors or bolstering retention of middle-aged donors would be most effective in maintaining the blood supply.

Variations in hemoglobin measurement and eligibility criteria across blood donation services are associated with differing low-hemoglobin deferral rates: a BEST Collaborative study.

BACKGROUND: Determination of blood donor hemoglobin (Hb) levels is a pre-requisite to ensure donor safety and blood product quality. We aimed to identify Hb measurement practices across blood donation services and to what extent differences associate with low-Hb deferral rates. METHODS: An online survey was performed among Biomedical Excellence for Safer Transfusion (BEST) Collaborative members, extended with published data. Multivariable negative-binomial regression models were built to estimate adjusted associations of minimum donation intervals, Hb cut-offs (high, ≥13.5 g/dL in men or ≥ 12.5 g/dL in women, vs. lower values), iron monitoring (yes/no), providing or prescribing iron supplementation (yes/no), post-versus pre-donation Hb measurement and geographical location (Asian vs. rest), with low-Hb deferral rates. RESULTS: Data were included from 38 blood services. Low-Hb deferral rates varied from 0.11% to 8.81% among men and 0.84% to 31.85% among women. Services with longer minimum donation intervals had significantly lower deferral rates among both women (rate ratio, RR 0.53, 95%CI 0.33-0.84) and men (RR 0.53, 95%CI 0.31-0.90). In women, iron supplementation was associated with lower Hb deferral rates (RR 0.47, 95%CI 0.23-0.94). Finally, being located in Asia was associated with higher low-Hb deferral rates; RR 9.10 (95%CI 3.89-21.27) for women and 6.76 (95%CI 2.45-18.68) for men. CONCLUSION: Differences in Hb measurement and eligibility criteria, particularly longer donation intervals and iron supplementation in women, are associated with variations in low-Hb deferral rates. These insights could help improve both blood donation service efficiency and donor care.

HIV residual risk in Canada under a three-month deferral for men who have sex with men.

BACKGROUND AND OBJECTIVES: In Canada, the deferral for men who have sex with men (MSM) was decreased from a permanent deferral to a 5-year then a 12-month deferral. Current HIV testing can detect an HIV infection in donated blood within 2 weeks of exposure; thus, a 12-month deferral may be unnecessarily restrictive. We aimed to estimate the residual risk of HIV if the deferral were further decreased to 3 months. MATERIALS AND METHODS: Using a deterministic model with stochastic Monte Carlo simulation, residual risk of HIV was the sum of testing error, assay sensitivity and window-period risks. Data inputs were estimated from donor surveillance, donor surveys and published data. Residual risk was modelled at baseline and using three scenarios: (1) most likely - non-compliance, HIV prevalence and incidence rates of MSM are unchanged; (2) optimistic - non-compliance improves by 50%; and (3) pessimistic - non-compliance, HIV prevalence and incidence rates of MSM all double. RESULTS: HIV residual risk at baseline was 1 in 36·0 million donations (95% CI 1 in 1 504 907 million, 10·5 million); in the most likely scenario 1 in 34·2 million (1 in 225 534 million, 8·7 million); in the optimistic scenario 1 in 36·0 million (1 in 282 618 million, 9·5 million); in the pessimistic scenario 1 in 16·7 million (1 in 39 469 million, 6·0 million). All confidence intervals overlapped. CONCLUSION: With very low modelled risk under a 12-month deferral, the additional risk with a 3-month deferral is very low. This is true even with a pessimistic scenario.

Prevalence of Babesia in Canadian blood donors: June-October 2018.

BACKGROUND: The erythrocytic protozoan parasite Babesia microti, the cause of human babesiosis, is transmitted not only by tick bites but also via blood transfusion. B. microti is endemic in the northeastern/upper midwestern United States, where partial screening of blood donations has been implemented. In Canada, a 2013 study of approximately 14,000 donors found no B. microti antibody-positive samples, suggesting low risk at that time. METHODS: Between June and October 2018, 50,752 Canadian donations collected from sites near the US border were tested for Babesia nucleic acid by transcription-mediated amplification (TMA). Reactive donations were tested for B. microti by IgG immunofluorescence assay and polymerase chain reaction. A subset of 14,758 TMA nonreactive samples was also screened for B. microti antibody. Donors who tested reactive/positive were deferred, asked about risk factors, and were requested to provide a follow-up sample for supplemental testing. RESULTS: One sample from Winnipeg, Manitoba, was TMA and antibody reactive. Of the 14,758 TMA-nonreactive donations tested for antibody, four reactive donations were identified from southwestern Ontario near Lake Erie. None of the interviewed donors remembered any symptoms, likely tick exposure, or relevant travel within Canada or the United States. CONCLUSIONS: This is the largest B. microti prevalence study performed in Canada. The results indicate very low prevalence, with only one TMA-confirmed-positive donation of 50,752 tested. This donor was from the only region in Canada where autochthonous infection has been reported. Seropositive donations in southwestern Ontario suggest low prevalence; travel should not be ruled out given the proximity to the US border.

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.

BACKGROUND: Some countries impose an upper age limit on whole blood and double RBC donation while others do not. We evaluated the safety of blood donation in older individuals (≥71 years), and their contribution to the blood supply of five countries. STUDY DESIGN AND METHODS: Twelve blood center members of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative from four countries with no upper age limit for whole blood and double RBC donation (Canada, New Zealand, England, and the United States) or an upper age limit of 80 (Australia) provided 2016 data on donors and donations, deferral rates, and vasovagal reactions by donor age and sex. Donors under age 24 were included in the number of total donors and donations, but not in deferral and reaction rate comparisons. RESULTS: Older donors accounted for 1.0% (New Zealand) to 4.3% (United States) of donors, and 1.5% (New Zealand) to 5.6% (United States) of donations; most were between ages 71 and 76. The deferral rate was higher in older compared to 24- to 70-year-old males, but very similar between older and younger females. In contrast, vasovagal reaction rates were either lower (male donors) or similar (female donor for reactions with loss of consciousness) in older compared to 24- to 70-year-old donors. CONCLUSIONS: Exclusion solely based on older age appears to be unwarranted based on safety concerns such as donor reactions. Healthy older individuals can continue to safely donate and make a significant contribution to the blood supply past arbitrary age limits.

Changing the deferral for men who have sex with men - an improved model to estimate HIV residual risk.

BACKGROUND AND OBJECTIVES: Eight published studies modelled the impact of changing from a lifetime to time-limited deferral for men who have sex with men (MSM); each predicted greater risk impact than has been observed. This study uses these previous efforts to develop an 'optimized' model to inform future changes to MSM deferrals. MATERIALS AND METHODS: HIV residual risk was calculated using observed HIV incidence/prevalence prior to the change in MSM deferral, then with the additional MSM expected under a 12-month deferral for five compliance scenarios, and finally using data observed after implementation of the deferral. Monte Carlo simulation calculated 95% confidence intervals (CI). RESULTS: The architecture of reviewed models was sound, and two were selected for combination into the optimized model. HIV risk estimated by this in the UK under MSM lifetime deferral was 0·102 (95% CI: 0·050-0·172) per million. The model predicted from a 27·8% decrease to a 47·6% increase depending upon compliance pre-implementation of the 12-month deferral. A decrease of 0·9% was observed post-implementation. For Canada, HIV risk under a 5-year deferral was 0·050 (95% CI: 0·00003-0·122) per million. Pre-implementation of the 12-month deferral, the model predicted from 30·2% decrease to 10-fold increase. A decrease of 47·0% was observed after implementation. CONCLUSION: The optimized model predicted HIV risk under 12-month MSM deferral in UK and Canada would remain low, and this was confirmed post-implementation. While the model is adaptable to other deferral scenarios, improved data quality would improve precision, particularly estimates of incidence in individuals likely to donate.

Changes in plasma unit distributions to hospitals over a 10-year period.

BACKGROUND: There are many influences on a hospital's demand for plasma. Pharmaceuticals are now being administered for many indications instead of plasma, although trauma resuscitation now emphasizes increased and early intervention with plasma. This multinational study evaluated changes in blood center plasma unit distributions over a 10-year period. STUDY DESIGN AND METHODS: Data on the total number and the ABO groups of plasma unit distributions were obtained from nine American blood collectors (ABCs) and nine national or provincial blood services (NPBS) from 2007 through 2016. Plasma distributions to trauma hospitals by five ABCs and four NPBS were also analyzed. RESULTS: The overall number of plasma unit distributions from ABCs decreased by 23.1% from 2007 to 2016, but the relative proportion of distributed AB plasma units increased during the same period. The NPBS (excluding the Japanese Red Cross [JRC]) also had a 35.4% decrease in the overall number of plasma unit distributions with an increase in the relative proportion of AB plasma distributions between 2007 and 2016. The JRC, however, reported an increase in the overall number of plasma distributions by 13.5% in 2016 compared to 2007. The proportion of low-titer A plasma distributions increased to 1.6% of total plasma distributions by ABCs in 2016. There was a trend of distributing increasing proportions of group AB plasma units to trauma hospitals over the 10-year period. CONCLUSION: Although the number of plasma unit distributions has decreased at many blood collectors over time, the proportion of AB units has increased at both ABCs and NPBS.

Human T-cell lymphotropic virus: A simulation model to estimate residual risk with universal leucoreduction and testing strategies in Canada.

BACKGROUND AND OBJECTIVES: In Canada, transfusion transmission risk of Human T-cell lymphotropic virus -I/II (HTLV) is addressed by universal leucoreduction and universal antibody testing. We aimed to estimate the risk with the current policy, if testing only first-time donors and if testing were stopped. MATERIALS AND METHODS: Monte Carlo simulation was employed to estimate the proportion of red cell concentrate, random donor platelet and apheresis platelet units that would be released into inventory in each scenario (10 billion donors each). The model estimated the number of HTLV-positive donations not intercepted by testing, randomly assigned the number of HTLV particles/100 leucocytes using proportions from published data and randomly selected a postleucoreduction leucocyte count from quality control data. Units were considered infectious if ≥9 × 104 copies of HTLV provirus. RESULTS: With universal leucoreduction in place, the residual risk of releasing an HTLV potentially infectious unit with universal testing was 1 in 1·2 billion units (0, 1 in 55·9 million), with testing only first-time donors 1 in 7·1 million (0, 1 in 1·05 million) and with no testing 1 in 1·0 million (0, 1 in 178 600). The efficacy of leucoreduction was >99·5% (lower bound 95·7%) for all scenarios. CONCLUSION: With universal leucoreduction in place, switching from universal testing to testing first-time donors would incur very low risk.

Mitigation of the threat posed to transfusion by donors traveling to Zika-affected areas: a Canadian risk-based approach.

BACKGROUND: The recent spread of the Zika virus to the Americas and the recognition that it can cause severe disease in the developing fetus has prompted the adoption of measures to mitigate the risk that this virus might pose to transfusion safety. In nonendemic countries, the risk to transfusion results from donors traveling to an endemic region. Canada implemented a 21-day temporary deferral for prospective donors who traveled to such regions. We present the rationale for this policy, including a quantitative risk assessment supported by a Monte Carlo simulation. STUDY DESIGN AND METHODS: The model considered the following parameters, each with specified values and ranges: the probability that a donor recently returned from a Zika-endemic region, the duration of travel to this region, the daily risk of acquiring Zika while in an endemic region, and the incubation and viremic periods. We ran the simulation 20 times, each with 10 million iterations. RESULTS: In the absence of any travel deferral, 32 donors (range, 20-46 donors) would be able to donate while still being at risk of transmitting Zika, corresponding to a rate of 1:312,500 (range, 1:217,000 to 1:500,000). None of these donors would be viremic beyond 21 days after returning from their travel, with a risk estimated at less than 1:200,000,000. CONCLUSIONS: A 21-day temporary travel deferral offers an extremely wide margin of safety for the possible transmission of Zika by a donation obtained from someone who recently returned from a country where the virus is circulating.

Determining the rate of underrecognition of West Nile virus neurologic disease in the province of Quebec in 2012.

BACKGROUND: During a major outbreak of West Nile virus (WNV) infection in the province of Quebec in 2012, public health authorities (PHAs) suspected underrecognition of West Nile neurologic disease (WNND). With data on acute infections detected in blood donors, an estimate of the degree of underrecognition was produced. STUDY DESIGN AND METHODS: All 2012 donors were tested for WNV infection with the use of reverse transcription-polymerase chain reaction (RT-PCR). With the number of cases detected, the number of donors tested, our estimate of the duration of viremia, an estimate of the population at risk, and the ratio of WNND to total cases, an expected number of WNND cases was calculated. A Monte Carlo simulation was used to estimate the range of several of these variables. RESULTS: Seventeen RT-PCR-positive donors were found among 52,309 donations tested. In the base case, the total number of cases was 16,095 and the expected number of WNND cases was 115. In the Monte Carlo simulation, the mean number of expected WNND cases was 136, and the median was 129. Since only 85 cases were reported to PHAs, it is estimated that between 26 and 37.5% of cases occurring in the province went undetected. CONCLUSION: The observation that close to one-third of cases of WNND went undetected because of the omission of appropriate laboratory testing indicates the need for improvement in the investigation of acute neurologic syndrome of suspected infectious etiology in Québec.

The association between frequency of blood donation and the occurrence of low birthweight, preterm delivery, and stillbirth: a retrospective cohort study.

BACKGROUND: Women who donate blood on a regular basis are at high risk of becoming iron depleted. Iron deficiency anemia has been shown to increase the risk of low birthweight and possibly preterm birth. Therefore, there is a concern that regular blood donation by female donors might adversely impact the well-being of their offspring. This retrospective cohort study examined the association between blood donation and the occurrence of adverse pregnancy outcomes. STUDY DESIGN AND METHODS: The study sample included 18,483 female blood donors in their childbearing years (age 18 to 45 years) who delivered during the period 2001 to 2011 in the province of Québec (Canada). The occurrence of low birthweight (<2500 g), preterm delivery (<37 weeks of gestation), and stillbirth was ascertained by linking the donor information with provincial birth and stillbirth registries. RESULTS: There was no association between the frequency of donation in the 2-year period before pregnancy and adverse pregnancy outcomes; compared to women who did not donate during that period, those who donated three or more donations (mean, 3.9 donations) had a relative risk of 0.83 (95% confidence interval [CI], 0.65-1.06) for low birthweight, 0.91 (95% CI, 0.75-1.11) for preterm birth, and 0.62 (95% CI, 0.18-2.12) for stillbirth. These associations remained unchanged after adjusting for baseline characteristics. CONCLUSION: Women who donate blood on a regular but moderate basis do not appear to be at higher risk of adverse pregnancy outcomes. These findings, while reassuring, will need to be replicated in different settings.