Implementation of sexual risk behavior donor screening in Canada.

BACKGROUND: The two Canadian blood suppliers, Canadian Blood Services and Héma-Québec, removed the time-based deferral for men who have sex with men and adopted criteria assessing sexual risk behaviors. We report the impact of these changes on the safety and adequacy of the Canadian blood supply. STUDY DESIGN AND METHODS: Since 2022, all donors are asked if (1) they have had a new partner and (2) more than one sexual partner in the last 3 months. Donors answering yes to either question are asked if they had anal sex in the last 3 months; if yes, they are deferred for 3 months. We followed HIV rates for the 18 months before and 14 (Héma-Québec) or 18 months (Canadian Blood Services) post-implementation and interviewed HIV-positive whole blood donors. We assessed the number and characteristics of whole blood donors answering yes to the two first questions with or without deferral. RESULTS: There were four HIV-positive donations out of 1,492,355 donations pre-implementation and four out of 1,447,772 post-implementation (0.27/100,000 vs. 0.28/100,000, p = 1.00). Post-implementation, one HIV-positive donor was non-compliant with multiple criteria, no risk factors were identified in the others. 3.2% of donors answered yes to questions (1) and/or (2); 0.17% were deferred for a new partner and/or more than one partner and anal sex. Deferral rates were highest in first time, younger donors, and similar in males and females. CONCLUSION: Implementation of sexual risk behavior donor screening resulted in unchanged HIV rates to date and a manageable deferral rate.

Decreasing parvovirus B19 and hepatitis A nucleic acid test positivity rates in Canadian plasma donors following the initiation of COVID-19 restriction in March 2020.

BACKGROUND AND OBJECTIVES: In Canada, plasma sent for fractionation is tested for both parvovirus B19 (B19V) and hepatitis A virus (HAV). This study compared positivity rates of B19 and HAV nucleic acid tests (NATs) in Canadian plasma samples for the pre-COVID-19 restriction era (2015 to end of February 2020 [Q1] 2020) and the post-COVID-19 restriction era. MATERIALS AND METHODS: Pooled EDTA plasma specimens were tested within 24 months of blood draw using the Procleix Panther System (Grifols Diagnostic Solutions Inc, San Diego, CA, USA) for B19V and HAV detection. Reactive pools were resolved by individual specimen testing. RESULTS: Between 1 January 2015, and 31 March 2022, 3,928,619 specimens from Canadian plasma donors were tested for B19V. For the same period, 3,922,954 specimens were tested for HAV. To account for a lag in specimen testing for up to 24 months, the data were divided into: (1) a pre-pandemic period (1 January 2015-31 March 2020; B19V tested n = 2,412,701, B19V NAT-positive n = 240 [0.01%], HAV tested n = 2,407,036, HAV NAT-positive n = 26 [0.001%]); (2) a two-year mixed-impact period (1 April 2020-31 March 2022; B19V tested n = 968,250, B19V NAT-positive n = 14 [0.001%], HAV tested n = 968,250, HAV NAT-positive n = 2 [0.0002%]); and (3) a pandemic-impact period (1 April 2022-31 March, 2023; B19V tested n = 597,668, B19V NAT-positive n = 3 [0.0005%], HAV tested n = 597,668, HAV NAT-positive n = 1 [0.0002%]). CONCLUSION: The percentage of B19V- and HAV-positive donations was significantly reduced from the pre-pandemic period to the pandemic-impact period.

Deferral of blood donors who have ever stayed in a Trypanosoma cruzi endemic area: An international survey.

BACKGROUND AND OBJECTIVES: Trypanosoma cruzi is the etiologic agent of Chagas disease (CD), an anthropozoonosis from the American continent that progresses from an acute phase to an indeterminate phase, followed by a chronic symptomatic phase in around 30% of patients. In countries where T. cruzi is not endemic, many blood transfusion services test blood donors who have stayed in an endemic country ('at-risk stay')-even if they do not present with other risk factors. However, the efficiency of this approach has been questioned. MATERIALS AND METHODS: On 18 September 2023, a worldwide survey was distributed among employees of blood transfusion services. The questions mainly pertained to CD's endemicity in the blood services' region, the current testing policy for T. cruzi and the number of confirmed positive results among donors with a prior at-risk stay alone (i.e., without other risk factors for T. cruzi infection). RESULTS: Twenty-six recipients completed the survey. Of the 22 (84.6%) blood services that operated in a non-endemic region, 9 (42.9%) tested donors for T. cruzi, including 8 (88.9%) that considered the travel history or the duration of the stay (alone) in their testing algorithm ('study blood services'). Over 93 years of observation among all study blood services, 2 donations from donors with an at-risk stay alone and 299 from those with other risk factors were confirmed positive for T. cruzi. CONCLUSION: The study findings question the utility of testing blood donors who have stayed in an endemic country without other risk factors.

Hepatitis B virus genotype surveillance in Canadian blood donors and a referred patient population, 2016-2021.

BACKGROUND AND OBJECTIVES: Hepatitis B virus (HBV) genotypes (A-H) have a distinct geographic distribution and are highly associated with the country of birth. Canada has experienced increased immigration over the past decade, primarily from regions where HBV is endemic. This study investigated the proportions and trends of HBV genotypes within blood donor and clinical populations of Canada over the period 2016-2021. MATERIALS AND METHODS: Study samples involved two cohorts: (1) Canadian blood donors (n = 246) deferred from donation due to HBV test positivity and (2) chronic HBV patients from across Canada (clinically referred population, n = 3539). Plasma or serum was extracted, and the surface antigen and/or polymerase-coding region was amplified and sequenced to determine genotype by phylogenetic analysis. RESULTS: Six (A-E, G) and eight (A-H) HBV genotypes were detected among deferred blood donors and the clinically referred population, respectively. Differences in HBV genotype proportions between the two cohorts were observed across Canada. Males comprised most of the referred population among genotypes A-E (p < 0.0001), except for genotypes B and C. The median age was younger among blood donors (36 years [range 17-72]) compared with the referred population (41 years [range 0-99]). Distinct trends of increasing (E, referred; B, blood donor) and decreasing genotype prevalence were observed over the study period. CONCLUSION: HBV genotypes in Canada are highly diverse, suggesting a large immigrant population. Observed trends in genotype prevalence and proportional differences among cohorts imply shifts among the HBV-infected population of Canada, which warrants continued surveillance.

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.

End of selection criteria based on sexual orientation: An international symposium on alternatives to donation deferral.

BACKGROUND AND OBJECTIVES: Until recently, gay, bisexual and other men who have sex with men (MSM) were deferred from donating blood for 3-12 months since the last male-to-male sexual contact. This MSM deferral has been discontinued by several high-income countries (HIC) that now perform gender-neutral donor selection. MATERIALS AND METHODS: An international symposium (held on 20-04-2023) gathered experts from seven HICs to (1) discuss how this paradigm shift might affect the mitigation strategies for transfusion-transmitted infections and (2) address the challenges related to gender-neutral donor selection. RESULTS: Most countries employed a similar approach for implementing a gender-neutral donor selection policy: key stakeholders were consulted; the transition was bridged by time-limited deferrals; donor compliance was monitored; and questions or remarks on anal sex and the number and/or type of sexual partners were often added. Many countries have now adopted a gender-neutral approach in which questions on pre- and post-exposure prophylaxis for human immunodeficiency virus (HIV) have been added (or retained, when already in place). Other countries used mitigation strategies, such as plasma quarantine or pathogen reduction technologies for plasma and/or platelets. CONCLUSION: The experience with gender-neutral donor selection has been largely positive among the countries covered herein and seems to be acceptable to stakeholders, donors and staff. The post-implementation surveillance data collected so far appear reassuring with regards to safety, although longer observation periods are necessary. The putative risks associated with HIV antiretrovirals should be further investigated.

International review of blood donation nucleic acid amplification testing.

BACKGROUND AND OBJECTIVES: Nucleic acid amplification testing (NAT), in blood services context, is used for the detection of viral and parasite nucleic acids to reduce transfusion-transmitted infections. This project reviewed NAT for screening blood donations globally. MATERIALS AND METHODS: A survey on NAT usage, developed by the International Society of Blood Transfusion Working Party on Transfusion-transmitted Infectious Diseases (ISBT WP-TTID), was distributed through ISBT WP-TTID members. Data were analysed using descriptive statistics. RESULTS: Forty-three responses were received from 32 countries. Increased adoption of blood donation viral screening by NAT was observed over the past decade. NAT-positive donations were detected for all viruses tested in 2019 (proportion of donations positive by NAT were 0.0099% for human immunodeficiency virus [HIV], 0.0063% for hepatitis C virus [HCV], 0.0247% for hepatitis B virus [HBV], 0.0323% for hepatitis E virus [HEV], 0.0014% for West Nile virus [WNV] and 0.00005% for Zika virus [ZIKV]). Globally, over 3100 NAT-positive donations were identified as NAT yield or solely by NAT in 2019 and over 22,000 since the introduction of NAT, with HBV accounting for over half. NAT-positivity rate was higher in first-time donors for all viruses tested except WNV. During 2019, a small number of participants performed NAT for parasites (Trypanosoma cruzi, Babesia spp., Plasmodium spp.). CONCLUSION: This survey captures current use of blood donation NAT globally. There has been increased NAT usage over the last decade. It is clear that NAT contributes to improving blood transfusion safety globally; however, there is a need to overcome economic barriers for regions/countries not performing NAT.

An international review of the characteristics of viral nucleic acid-amplification testing (NAT) reveals a trend towards the use of smaller pool sizes and individual donation NAT.

BACKGROUND AND OBJECTIVES: Nucleic acid-amplification testing (NAT) is used for screening blood donations/donors for blood-borne viruses. We reviewed global viral NAT characteristics and NAT-yield confirmatory testing used by blood operators. MATERIALS AND METHODS: NAT characteristics and NAT-yield confirmatory testing used during 2019 was surveyed internationally by the International Society of Blood Transfusion Working Party Transfusion-Transmitted Infectious Diseases. Reported characteristics are presented herein. RESULTS: NAT was mainly performed under government mandate. Human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) NAT was performed on all donors and donation types, while selective testing was reported for West Nile virus, hepatitis E virus (HEV), and Zika virus. Individual donation NAT was used for HIV, HCV and HBV by ~50% of responders, while HEV was screened in mini-pools by 83% of responders performing HEV NAT. Confirmatory testing for NAT-yield samples was generally performed by NAT on a sample from the same donation or by NAT and serology on samples from the same donation and a follow-up sample. CONCLUSION: In the last decade, there has been a trend towards use of smaller pool sizes or individual donation NAT. We captured characteristics of NAT internationally in 2019 and provide insights into confirmatory testing approaches used for NAT-yields, potentially benefitting blood operators seeking to implement NAT.

Transfusion-transmitted Babesia spp.: a changing landscape of epidemiology, regulation, and risk mitigation.

Babesia spp. are tick-borne parasites with a global distribution and diversity of vertebrate hosts. Over the next several decades, climate change is expected to impact humans, vectors, and vertebrate hosts and change the epidemiology of Babesia. Although humans are dead-end hosts for tick-transmitted Babesia, human-to-human transmission of Babesia spp. from transfusion of red blood cells and whole blood-derived platelet concentrates has been reported. In most patients, transfusion-transmitted Babesia (TTB) results in a moderate-to-severe illness. Currently, in North America, most cases of TTB have been described in the United States. TTB cases outside North America are rare, but case numbers may change over time with increased recognition of babesiosis and as the epidemiology of Babesia is impacted by climate change. Therefore, TTB is a concern of microbiologists working in blood operator settings, as well as in clinical settings where transfusion occurs. Microbiologists play an important role in deploying blood donor screening assays in Babesia endemic regions, identifying changing risks for Babesia in non-endemic areas, investigating recipients of blood products for TTB, and drafting TTB policies and guidelines. In this review, we provide an overview of the clinical presentation and epidemiology of TTB. We identify approaches and technologies to reduce the risk of collecting blood products from Babesia-infected donors and describe how investigations of TTB are undertaken. We also describe how microbiologists in Babesia non-endemic regions can assess for changing risks of TTB and decide when to focus on laboratory-test-based approaches or pathogen reduction to reduce TTB risk.

Monitoring syphilis serology in blood donors: Is there utility as a surrogate marker of early transfusion transmissible infection behavioral risk?

BACKGROUND: In Canada the time deferral for gay, bisexual, and other men who have sex with men (gbMSM) was progressively shortened (lifetime, 5 years, 1 year, 3 months). Here we describe trends in syphilis rates (a potential sexual risk marker) and risk behaviors from blood donors in the past 12 years. STUDY DESIGN AND METHODS: Syphilis positivity in 10,288,322 whole blood donations (January 1, 2010-September 10, 2022) and gbMSM deferral time periods, donation status, age, and sex were analyzed with logistic regression. Overall, 26.9% syphilis positive and 42.2% controls (matched 1:4) participated in risk factor interviews analyzed by logistic regression. RESULTS: Syphilis rates were higher in first-time donors (OR 27.0, 95% CI 22.1-33.0), in males (OR 2.3, 1.9-2.8) and with the 3-month deferral (OR 3.4, 2.6-4.3) during which the increase was greater for first-time males (p < .001) but similar for male and female repeat donors (p > .05). Among first-time donors, histories of intravenous drug use (OR 11.7, 2.0-69.5), male-to-male sex 7.8 (2.0-30.2) and birth in a high prevalence country (OR 7.6, 4.4-13.0) predicted syphilis positivity; among repeat donors, history of male-to-male sex (OR 33.5, CI 3.5-317.0). All but 1 gbMSM syphilis-positive donors were noncompliant with the gbMSM deferral. About a quarter of first-time interviewed case donors had history of syphilis; 44% were born in a high-prevalence country. CONCLUSION: Rising syphilis rates in donors correlates with the general population epidemic. Recent infection rates rose similarly in males and females. GbMSM history may contribute to donor syphilis rates but shortening time deferrals appears unrelated.

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.

BACKGROUND: In 2021, Canada implemented a pilot plasma program allowing some sexually active men who have sex with men (including but not limited to gay and bisexual men; gbMSM) to donate plasma. Changes to plasma donation policy could help address inequities in access to plasma donation and increase Canada's domestically collected plasma supply if more gbMSM donate as a result. We aimed to (1) examine views regarding plasma donation and the pilot program prior to implementation and (2) identify modifiable theory-informed predictors of gbMSM's intention to donate plasma. METHODS: We developed, piloted, and disseminated a questionnaire informed by the Theoretical Domains Framework (TDF). We recruited gbMSM in London (ON) and Calgary (AB) to an anonymous, online cross-sectional survey. RESULTS: A total of 246 gbMSM completed the survey. On scales from 1 (strongly disagree) to 5 (strongly agree), general intention to donate was high (mean = 4.24; SD = 0.94). The pilot program itself was mostly acceptable (mean = 3.71, SD = 1.16), but the intention to donate under the unique requirements of the pilot program was lower than general intention (mean = 3.58; SD = 1.26). Two domains from the theoretical domains framework (TDF) (beliefs about consequences of donating plasma and social influences) were independently associated with general intention to donate. DISCUSSION: The pilot plasma program as an incremental step toward more inclusive policies was mostly viewed as acceptable by the impacted communities. Historical and ongoing exclusions create unique barriers to donation. There are clear opportunities for developing theory-informed interventions to support gbMSM to donate plasma as policies continue to become more inclusive and more become eligible to donate.

Medication use in Canadian blood donors.

BACKGROUND AND OBJECTIVES: Policies regarding medication use vary between blood centres. We evaluated medication use in eligible Canadian Blood Services whole blood donors to inform possible process improvements and allow comparisons between donors and the general population. MATERIALS AND METHODS: All donors are asked about medication use in the last 3 days, and medications and their reason for use are documented in our donor computer system. Donor computer records were reviewed from January 1, 2020, to March 31, 2022 to extract information on medications by donor age and sex; medications were grouped into therapeutic classes. Stability of medication use over time was determined in a random sample of 100 donors who made at least two donations in the study period. RESULTS: One-third of successful (eligible) donors were taking medications; of these, 80% were on one or two medications. Five classes of medication accounted for 72% of medication use, and 13 classes account for 93% of use. Use remains relatively stable over time. CONCLUSION: Medication use is common, with a few classes accounting for most use. Drop-down lists and storage of information from one donation to the next may enhance efficiency.

Use of selective phenotyping and genotyping to identify rare blood donors in Canada.

BACKGROUND AND OBJECTIVES: The distribution of rare and specific red cell phenotypes varies between races and ethnicities. Therefore, the most compatible red cell units for patients with haemoglobinopathies and other rare blood requirements are most likely to be found in donors from similar genetic backgrounds. Our blood service introduced a voluntary question asking donors to provide their racial background/ethnicity. Results triggered additional phenotyping and/or genotyping. MATERIALS AND METHODS: We analysed the results of additional testing performed between January 2021 and June 2022, and rare donors were added to the Rare Blood Donor database. We determined the incidence of various rare phenotypes and blood group alleles based on donor race/ethnicity. RESULTS: Over 95% of donors answered the voluntary question; 715 samples were tested, and 25 donors were added to the Rare Blood Donor database, including five k-, four U-, two Jk(a-b-) and two D- - phenotypes. CONCLUSION: Asking donors about their race/ethnicity was well received by donors, and the resulting selective testing enabled us to identify individuals with a higher likelihood of being rare blood donors, support patients with rare blood requirements and better understand the incidence of common and rare alleles and red blood cell phenotypes in the Canadian donor population.

Evolving the gay, bisexual and other men who have sex with men time-based deferral to sexual risk screening for all donors: The contribution of Canadian research programmes.

BACKGROUND AND OBJECTIVES: In Canada, the time deferral for gay, bisexual and other men who have sex with men (gbMSM) to donate blood has gradually decreased. In September 2022, this deferral was replaced with sexual behaviour-based screening for all donors. We investigate how data from targeted research programmes addressed knowledge gaps to support this change. MATERIALS AND METHODS: We conducted a scoping review describing the Canadian literature available before the research programmes relating to (1) behavioural indicators of HIV risk and (2) attitudes to blood donation among gbMSM, current donors and the general population. We summarize the targeted research programmes, their outputs and impact to date. RESULTS: For question 1, five projects met inclusion criteria. For question 2, three articles met inclusion criteria. Knowledge gaps identified were insufficient evidence of HIV incidence in gbMSM who met other donor eligibility criteria and scant data on opinions and views of blood donation and screening criteria for sexual risk behaviours. The research programmes funded 19 projects at 11 different research sites involving over 100 individual researchers/collaborators resulting in 19 peer-reviewed publications to date. Leveraging existing gbMSM cohorts yielded relevant HIV incidence data to inform safety modelling studies. Findings indicated that sexual behaviour-based screening was acceptable to gbMSM and donors, and donor discomfort around specific questions could be mitigated with clear explanations. CONCLUSION: Targeted research programmes filled critical knowledge gaps and informed a change to gender-neutral, sexual behaviour-based screening for all donors. Findings supported successful implementation of these changes with research-informed staff training.

Risk of variant Creutzfeldt-Jakob disease in a simulated cohort of Canadian blood donors.

BACKGROUND AND OBJECTIVES: No transfusion-associated cases of variant Creutzfeldt-Jakob disease (vCJD) have occurred in more than 20 years. Yet, many countries have maintained blood donor deferral criteria for vCJD. We developed a risk simulation model to reassess the need for vCJD-related deferral criteria in Canada. MATERIALS AND METHODS: The model provides results separately for Héma-Québec (HQ) and Canadian Blood Services (CBS). The model used a Monte Carlo simulation approach to estimate the risk of having a vCJD-contaminated blood donation ('risk of vCJD') in a simulated cohort of 10 million donors followed for up to 85 years. The model assumed current deferral criteria for vCJD were lifted, which would allow new 'at-risk' donors to give blood. The model accounted for disease prevalence, donors' travel/immigration history, PRNP genotype at codon 129, demographics and the type of labile blood product. RESULTS: In the base case, the risk of vCJD was estimated at zero at both blood services. In the most pessimistic scenario, the risk of vCJD was 6.4 × 10-9 (i.e., 1 in 157 million donations) at HQ, or ≤1 in 77 million based on the upper bound of the 95% confidence interval (CI). At CBS, this risk was 4.8 × 10-8 (i.e., 1 in 21 million donations), or ≤1 in 16 million based on the upper bound of the 95% CI. CONCLUSION: vCJD poses minimal risks to the Canadian blood supply. Current vCJD deferral criteria may, therefore, be lifted with virtually no impact on safety, while significantly expanding the donor base.

White paper on pandemic preparedness in the blood supply.

BACKGROUND AND OBJECTIVES: In March 2020, the WHO declared the SARS-CoV-2 corona virus a pandemic which caused a great disruption to global society and had a pronounced effect on the worldwide supply of blood. MATERIALS AND METHODS: In 2022 an on-line meeting was organised with experts from Austria, Canada, Germany, Greece, Netherlands and United States to explore the opportunities for increasing preparedness within blood systems for a potential future pandemic with similar, or more devastating, consequences. The main themes included the value of preparedness, current risks to the blood supply, supply chain vulnerabilities, and the role of innovation in increasing resiliency and safety. RESULTS: Seven key recommendations were formulated and including required actions at different levels. CONCLUSION: Although SARS-CoV-2 might be seen as a unique event, global health risks are expected to increase and will affect blood transfusion medicine if no preparedness plans are developed.

The evolution of SARS-CoV-2 seroprevalence in Canada: a time-series study, 2020-2023.

BACKGROUND: During the first year of the COVID-19 pandemic, the proportion of reported cases of COVID-19 among Canadians was under 6%. Although high vaccine coverage was achieved in Canada by fall 2021, the Omicron variant caused unprecedented numbers of infections, overwhelming testing capacity and making it difficult to quantify the trajectory of population immunity. METHODS: Using a time-series approach and data from more than 900 000 samples collected by 7 research studies collaborating with the COVID-19 Immunity Task Force (CITF), we estimated trends in SARS-CoV-2 seroprevalence owing to infection and vaccination for the Canadian population over 3 intervals: prevaccination (March to November 2020), vaccine roll-out (December 2020 to November 2021), and the arrival of the Omicron variant (December 2021 to March 2023). We also estimated seroprevalence by geographical region and age. RESULTS: By November 2021, 9.0% (95% credible interval [CrI] 7.3%-11%) of people in Canada had humoral immunity to SARS-CoV-2 from an infection. Seroprevalence increased rapidly after the arrival of the Omicron variant - by Mar. 15, 2023, 76% (95% CrI 74%-79%) of the population had detectable antibodies from infections. The rapid rise in infection-induced antibodies occurred across Canada and was most pronounced in younger age groups and in the Western provinces: Manitoba, Saskatchewan, Alberta and British Columbia. INTERPRETATION: Data up to March 2023 indicate that most people in Canada had acquired antibodies against SARS-CoV-2 through natural infection and vaccination. However, given variations in population seropositivity by age and geography, the potential for waning antibody levels, and new variants that may escape immunity, public health policy and clinical decisions should be tailored to local patterns of population immunity.

Improved access yet inequitable experience: gay, bisexual and other men who have sex with men's views of more inclusive criteria for source plasma donation.

BACKGROUND: Canada has incrementally reduced restrictions to blood and plasma donation that impact men who have sex with men, gay, bisexual, and queer men, and some Two Spirit, transgender and non-binary individuals (MSM/2SGBTQ+). Prior to the launch of a pilot program in 2021 enabling some MSM/2SGBTQ + to donate source plasma, we explored the acceptability of the program among individuals who could become eligible to donate in the program. METHODS: We invited men identifying as MSM/2SGBTQ + to participate in two consecutive semi-structured interviews to explore their views on blood and plasma donation policy, plasma donation, and the proposed Canadian plasma donation program. Interview transcripts were analyzed thematically and acceptability-related themes were mapped onto the Theoretical Framework of Acceptability. RESULTS: Twenty-seven men identifying as having sex with men participated in 53 interviews. Eighteen themes were mapped onto the seven construct domains of the Theoretical Framework of Acceptability. Underlying all aspects of acceptability was a tension between four primary values influencing participants' views: altruism, equity, supply sufficiency, and evidence-based policy. The program was viewed as welcome progress on a discriminatory policy, with many excited to participate, yet tension with inequitable aspects of the program undermined support for the program and interest to contribute to it. The high demands of the program are unique for MSM/2SGBTQ + and are only tolerable as part of a program that is an incremental and instrumental step to more equitable donation policies. CONCLUSION: Findings highlight past experiences of exclusion in Canada as a unique and critical part of the context of the donation experience among MSM/2SGBTQ+. Despite the program's goals of greater inclusivity of MSM/2SGBTQ + individuals, the anticipated experience of the program included continued stigmatization and inequities. Future research should seek to understand the experienced views of MSM/2SGBTQ + donors to ensure that as policies change, policies are implemented equitably.

A Higher Antibody Response Is Generated With a 6- to 7-Week (vs Standard) Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccine Dosing Interval.

The optimal dosing interval for severe acute respiratory syndrome coronavirus 2 vaccines remains controversial. In this prospective study, we compared serology results of paramedics vaccinated with mRNA vaccines at the recommended short (17-28 days) vs long (42-49 days) interval. We found that a long dosing interval resulted in higher spike, receptor binding domain, and spike N terminal domain antibody concentrations.

Epidemiology of Hospitalized Patients with Babesiosis, United States, 2010-2016.

Babesia spp. are tickborne parasites that cause the clinical infection babesiosis, which has an increasing incidence in the United States. We performed an analysis of hospitalizations in the United States during 2010-2016 in which babesiosis was listed as a diagnosis. We used the National Inpatient Sample database to characterize the epidemiology of Babesia-associated admissions, reflecting severe Babesia-related disease. Over a 7-year period, a total of 7,818 hospitalizations listed babesiosis as a primary or secondary admitting diagnosis. Hospitalizations were seasonal (71.2% occurred during June-August) and situated overwhelmingly in the Northeast and Midwest. The patients were predominantly male and of advanced age, which is consistent with the expected epidemiology. Despite a higher severity of illness in more than (58.5%), the mortality rate was low (1.6%). Comparison with state reporting data suggests that the number of hospitalized persons with babesiosis increased modestly during the observation period.