Porcine-derived pancreatic enzyme replacement therapy may be linked to chronic hepatitis E virus infection in cystic fibrosis lung transplant recipients.

OBJECTIVES: In high-income countries hepatitis E virus (HEV) is an uncommonly diagnosed porcine-derived zoonoses. After identifying disproportionate chronic HEV infections in persons with cystic fibrosis (pwCF) postlung transplant, we sought to understand its epidemiology and potential drivers. DESIGN: All pwCF post-transplant attending our regional CF centre were screened for HEV. HEV prevalence was compared against non-transplanted pwCF and with all persons screened for suspected HEV infection from 2016 to 2022 in Alberta, Canada. Those with chronic HEV infection underwent genomic sequencing and phylogenetic analysis. Owing to their swine derivation, independently sourced pancreatic enzyme replacement therapy (PERT) capsules were screened for HEV. RESULTS: HEV seropositivity was similar between transplanted and non-transplanted pwCF (6/29 (21%) vs 16/83 (19%); p=0.89). Relative to all other Albertans investigated for HEV as a cause of hepatitis (n=115/1079, 10.7%), pwCF had a twofold higher seropositivity relative risk and this was four times higher than the Canadian average. Only three chronic HEV infection cases were identified in all of Alberta, all in CF lung transplant recipients (n=3/29, 10.3%). Phylogenetics confirmed cases were unrelated porcine-derived HEV genotype 3a. Ninety-one per cent of pwCF were taking PERT (median 8760 capsules/person/year). HEV RNA was detected by RT-qPCR in 44% (47/107) of PERT capsules, and sequences clustered with chronic HEV cases. CONCLUSION: PwCF had disproportionate rates of HEV seropositivity, regardless of transplant status. Chronic HEV infection was evident only in CF transplant recipients. HEV may represent a significant risk for pwCF, particularly post-transplant. Studies to assess HEV incidence and prevalence in pwCF, and potential role of PERT are required.

International review of blood donation screening for anti-HBc and occult hepatitis B virus infection.

BACKGROUND: Hepatitis B core antibody (anti-HBc) screening has been implemented in many blood establishments to help prevent transmission of hepatitis B virus (HBV), including from donors with occult HBV infection (OBI). We review HBV screening algorithms across blood establishments globally and their potential effectiveness in reducing transmission risk. MATERIALS AND METHODS: A questionnaire on HBV screening and follow-up strategies was distributed to members of the International Society of Blood Transfusion working party on transfusion-transmitted infectious diseases. Screening data from 2022 were assimilated and analyzed. RESULTS: A total of 30 unique responses were received from 25 countries. Sixteen respondents screened all donations for anti-HBc, with 14 also screening all donations for HBV DNA. Anti-HBc prevalence was 0.42% in all blood donors and 1.19% in new donors in low-endemic countries; however, only 44% of respondents performed additional anti-HBc testing to exclude false reactivity. 0.68% of anti-HBc positive, HBsAg-negative donors had detectable HBV DNA. Ten respondents did universal HBV DNA screening without anti-HBc, whereas four respondents did not screen for either. Deferral strategies for anti-HBc positive donors were highly variable. One transfusion-transmission from an anti-HBc negative donor was reported. DISCUSSION: Anti-HBc screening identifies donors with OBI but also results in the unnecessary deferral of a significant number of donors with resolved HBV infection and donors with false-reactive anti-HBc results. Whilst confirmation of anti-HBc results could be improved to reduce donor deferral, transmission risks associated with anti-HBc negative OBI donors must be considered. In high-endemic areas, highly sensitive HBV DNA testing is required to identify infectious donors.

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.

Higher rates of laboratory-confirmed cases of syphilis in Western Canadian blood donors compared with Eastern Canadian blood donors following a period of societal re-opening.

BACKGROUND AND OBJECTIVES: There is a growing infectious syphilis outbreak in Western Canada. Although blood donors are screened for syphilis risks, some blood donors will still be confirmed test-positive for syphilis. This study compares the characteristics of confirmed test-positive syphilis donations in both Western Canada and Eastern Canada, November 2022-August 2023. MATERIALS AND METHODS: Donors were defined as Western or Eastern Canadian. Blood donations were tested for syphilis using the PK-TP assay (Beckman Coulter PK7300 Automated Microplate System). Confirmatory Treponema pallidum particle agglutination (TPPA) and rapid plasma reagin (RPR) assays were performed by one of two reference laboratories. An RPR titre ≥1:8 was used as a proxy for possible infectious syphilis. RESULTS: Rates of laboratory-confirmed syphilis were higher in Western (n = 43, 13.4/100,000 donations) versus Eastern donors (n = 19, 4.7/100,000 donations; Fisher's exact test, two-sided, p ≤ 0.0001). Most syphilis confirmations were in first-time donors (Western Canada n = 31/43, 72.1%, Eastern Canada 12/19, 63.2%). CONCLUSION: Although rates of laboratory-confirmed syphilis were higher in Western versus Eastern donors, Western donors did not have higher rates of infectious syphilis. Further studies might assess whether donors with laboratory-confirmed syphilis understood pre-donation screening questions or were completely unaware of a past infection.

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.

Epidemiology of Hepatitis C over 28 years of monitoring Canadian blood donors: Insight into a low-risk undiagnosed population.

BACKGROUND: Hepatitis C is a blood-borne infection with the hepatitis C virus (HCV) that can progress to cirrhosis and liver cancer. About 70% (50-80%) of infections become chronic and exhibit anti-HCV and HCV nucleic acid (NAT) positivity. Direct acting oral pan genotypic antiviral treatment became available in 2014 and was free for most Canadians in 2018. Clinical screening for HCV infection is risk-based. About 1% of Canadians have been infected with HCV, with 0.5% chronically infected (about 25% unaware) disproportionately impacting marginalized groups. Blood donors are in good health, are deferred for risks such as injection drug use and can provide insight into the low-risk undiagnosed population. Here we describe HCV epidemiology in first-time blood donors over 28 years of monitoring. METHODS: All first-time blood donors in all Canadian provinces except Quebec (1993 to 2021) were analyzed. All blood donations were tested for HCV antibodies (anti-HCV) and since late 1999 also HCV NAT. A case-control study was also included. All HCV positive donors (cases) since 2005 and HCV negative donors (1:4 ratio controls) matched for age, sex and location were invited to complete a risk factor interview. Separate logistic regression models for anti-HCV positivity and chronic HCV assessed the association between age cohort, sex, region and neighbourhood material deprivation and ethnocultural concentration. CASE: control data were analysed by logistic regression. RESULTS: There were 2,334,238 donors from 1993 to 2021 included. Prevalence for anti-HCV was 0.33% (0.30,0.37) in 1993 and 0.07% (0.05,0.09) in 2021 (p < 0.0001). In 2021 0.03% (0.01,0.04) had chronic HCV. Predictors for both anti-HCV positivity and chronic HCV were similar, for chronic HCV were male sex (OR 1.8, 1.6,2.1), birth between 1945 and 1975 (OR 7.1, 5.9,8.5), living in the western provinces (OR 1.4, 1.2,1.7) and living in material deprived (OR 2.7, 2.1,3.5) and more ethnocultural concentrated neighbourhoods (OR 1.8, 1.3,2.5). There were 318 (35.4%) of chronic HCV positive and 1272 (39.6%) of controls who participated in case control interviews. The strongest risks for acquisition were injection drug use (OR 96.9, 22.3,420.3) and birth in a high prevalence country (OR 24.5, 11.2,53.6). CONCLUSIONS: Blood donors have 16 times lower HCV prevalence then the general population. Donors largely mirror population trends and highlight the ongoing prevalence of untreated infections in groups without obvious risks for acquisition missed by risk-based patient screening.

The Relationship Between Anti-Spike SARS-CoV-2 Antibody Levels and Risk of Breakthrough COVID-19 Among Fully Vaccinated Adults.

The relationship between antibodies to wild-type severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens and the risk of breakthrough infections is unclear, especially during circulation of the Omicron strain. We investigated the association of anti-spike and anti-receptor binding domain antibody levels and the risk of subsequent breakthrough coronavirus disease 2019 (COVID-19). We included adult paramedics from an observational cohort study who received 2 mRNA vaccines but did not have COVID-19 before the blood collection. Higher postvaccination antibody levels to wild-type SARS-CoV-2 antigens were associated with a reduced risk of COVID-19. Further research into clinical utility of antibody levels, to inform a threshold for protection and timing of boosters, should be prioritized.

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.

Canadian Blood Services traceback investigation of a suspected case of transfusion-transmitted malaria.

BACKGROUND: A 4-month-old infant hospitalized since birth received multiple blood transfusions. In March 2022, Plasmodium falciparum was confirmed with nucleic acid testing. As the mother was assessed as unlikely to be the source of infection, the blood operator initiated a traceback investigation for a potential blood donor source. The patient had received 13 red blood cell (RBC) transfusions (aliquoted from 11 donors), 4 apheresis platelet (PLT) transfusions and 16 buffy coat pooled PLT transfusions. The blood operator medical team developed a supplementary malaria infection risk questionnaire to identify donors at highest risk of life-time malaria infection, based on birthplace, residence, or travel in malaria-endemic regions. RESULTS: With 79 donors initially implicated, initial focus was on donors of RBC components. The 11 RBC donors were contacted and assessed using the supplementary questionnaire. Three donors, all of whom met current malaria-related donor eligibility criteria, were deemed high risk of prior malaria infection. These donors consented to P. falciparum serology and nucleic acid testing (NAT). One donor who was born and had resided in an endemic West African country for 14 years, was positive for P. falciparum by serology (indirect fluorescent antibody test) and NAT-(Ct ≥32). Lookback of this donor's transfused fresh co-components and prior donation identified no other malaria cases. CONCLUSION: This was a probable transfusion-transmitted malaria (TTM) case from an eligible donor who in retrospect was found to have unrecognized, asymptomatic, semi-immune malaria infection, and who was potentially infectious. Blood donor lack of recall of prior malaria infection does not negate the risk of TTM from those who have lived in malaria-endemic countries.

Monitoring viral genomic sequences in transfusion-transmitted viruses.

BACKGROUND AND OBJECTIVES: Monitoring genomic sequences of blood-borne viruses infecting blood donors enables blood operators to undertake molecular epidemiology, confirm transfusion transmission and assess and characterize molecular and serological screening assays. The purpose of the study was to determine how blood operators globally value viral diversity surveillance and to assess its impact. MATERIALS AND METHODS: An electronic questionnaire was developed and circulated to members of the International Society of Blood Transfusion-transmitted infectious diseases working party. Responses were compiled and complete data sets were analysed. RESULTS: Ninety-seven percent of respondents agreed that monitoring viral genomic sequences was important to blood operators and the transfusion community. However, only 47% of respondents are currently doing this monitoring. The main limitations reported were a lack of financial resources and expertise. Sequencing techniques, primarily next-generation sequencing and also Sanger sequencing, were considered most appropriate, with the preferred option for testing being regional or national reference centres. Respondents agreed that engagement with public health authorities needs to be enhanced. CONCLUSION: Monitoring genomic sequences of blood-borne viruses is widely considered important by the transfusion community because of its direct applications for transfusion safety, and beyond for public health in general. Therefore, there is a need to strengthen collaboration between blood operators and public health authorities. While national and regional reference centres may be the most appropriate structure for such testing, international collaborations should not be overlooked. Overcoming financial barriers will be an important hurdle for many.

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.

Molecular Screening of Blood Donors for Babesia in Tyrol, Austria.

Introduction: Babesia is a tick-borne intraerythrocytic parasite that is globally ubiquitous, yet understudied. Several species of Babesia have been shown to be transfusion-transmissible. Babesia has been reported in blood donors, animals, and ticks in the Tyrol (Western Austria), and regional cases of human babesiosis have been described. We sought to characterize the risk of Babesia to the local blood supply. Methods: Prospective molecular testing was performed on blood donors who presented to regional, mobile blood collection drives in the Tyrol, Austria (27 May to October 4, 2021). Testing was conducted using the cobas® Babesia assay (Roche Molecular Systems, Inc.), a commercial PCR assay approved for blood donor screening that is capable of detecting the 4 primary species causing human babesiosis (i.e., B. microti, B. divergens, B. duncani, and B. venatorum). A confirmatory algorithm to manage initial PCR-reactive samples was developed, as were procedures for donor and product management. Results: A total of 7,972 donors were enrolled and screened; 4,311 (54.1%) were male, with a median age of 47 years (IQR = 34-55). No positive cases of Babesia were detected, corresponding with an overall prevalence of 0.00% (95% CI: 0.00%, 0.05%). Discussion: The findings suggest that the prevalence of Babesia is low in Austrian blood donors residing in the Tyrol, even during months of peak tick exposure. Although one cannot conclude the absence of Babesia in this population given the limited sample size, the findings suggest that the regional risk of transfusion-transmitted babesiosis is low.

Influenza Vaccine Effectiveness by A(H3N2) Phylogenetic Subcluster and Prior Vaccination History: 2016-2017 and 2017-2018 Epidemics in Canada.

BACKGROUND: The influenza A(H3N2) vaccine was updated from clade 3C.3a in 2015-2016 to 3C.2a for 2016-2017 and 2017-2018. Circulating 3C.2a viruses showed considerable hemagglutinin glycoprotein diversification and the egg-adapted vaccine also bore mutations. METHODS: Vaccine effectiveness (VE) in 2016-2017 and 2017-2018 was assessed by test-negative design, explored by A(H3N2) phylogenetic subcluster and prior season's vaccination history. RESULTS: In 2016-2017, A(H3N2) VE was 36% (95% confidence interval [CI], 18%-50%), comparable with (43%; 95% CI, 24%-58%) or without (33%; 95% CI, -21% to 62%) prior season's vaccination. In 2017-2018, VE was 14% (95% CI, -8% to 31%), lower with (9%; 95% CI, -18% to 30%) versus without (45%; 95% CI, -7% to 71%) prior season's vaccination. In 2016-2017, VE against predominant clade 3C.2a1 viruses was 33% (95% CI, 11%-50%): 18% (95% CI, -40% to 52%) for 3C.2a1a defined by a pivotal T135K loss of glycosylation; 60% (95% CI, 19%-81%) for 3C.2a1b (without T135K); and 31% (95% CI, 2%-51%) for other 3C.2a1 variants (with/without T135K). VE against 3C.2a2 viruses was 45% (95% CI, 2%-70%) in 2016-2017 but 15% (95% CI, -7% to 33%) in 2017-2018 when 3C.2a2 predominated. VE against 3C.2a1b in 2017-2018 was 37% (95% CI, -57% to 75%), lower at 12% (95% CI, -129% to 67%) for a new 3C.2a1b subcluster (n = 28) also bearing T135K. CONCLUSIONS: Exploring VE by phylogenetic subcluster and prior vaccination history reveals informative heterogeneity. Pivotal mutations affecting glycosylation sites, and repeat vaccination using unchanged antigen, may reduce VE.

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.

How do we decide how representative our donors are for public health surveillance?

BACKGROUND: Surveillance of blood donors is fundamental to safety of the blood supply. Such data can also be useful for public health policy but tend to be underutilized. When the COVID-19 pandemic arrived, blood centers around the world measured blood donor SARS-CoV-2 seroprevalence to inform public health policy. There is now a movement toward blood centers becoming more involved in public health research and surveillance post-pandemic. However, blood donors are a healthy population and not representative of all segments of the general population. In this article, we explain how blood centers can evaluate their donor base to understand which part of the general population they are representative of. STUDY DESIGN AND METHODS: Methodologic approaches for evaluating samples relative to the target population were reviewed. Blood donor data that are available to most blood centers were identified and application to assess representativeness of blood donors was evaluated. RESULTS: Key aspects of blood donor data to compare with general population data include donor selection criteria, health indicators, geography, and demographics. In some cases, statistical adjustment can improve representativeness. DISCUSSION: Comparing key blood donor data with corresponding general population data can define the subset of the general population for which a particular blood center's donors may be representative of. We suggest that donors are an ideal convenience population for surveillance of infectious agents which are frequently asymptomatic and main routes of transmission are not deferrable, for studying the natural history of disease in an initially well population, and for vaccination serology surveillance.

Resistance of SARS-CoV-2 beta and gamma variants to plasma collected from Canadian blood donors during the spring of 2020.

BACKGROUND: This pilot study assesses the ability of plasma collected from Canadian blood donors in the first wave of the SARS-CoV-2 pandemic to neutralize later SARS-CoV-2 variants of concern (VOCs). STUDY DESIGN AND METHODS: A repeated cross-sectional design was used, and a random cross-sectional sample of all available Canadian Blood Services retention samples (n = 1500/month) was drawn monthly for April and May of 2020. Qualitative IgG analysis was performed on aliquots of specimens using anti-spike, anti-receptor binding domain, and anti-nucleocapsid protein enzyme-linked immunosorbent assays as well as the Abbott Architect SARS CoV-2 IgG assay (Abbott Laboratories) against the anti-nucleocapsid protein. Selected plasma specimens were then assessed for neutralization against VOCs using pseudotyped lentivirus inhibition assays as well as plaque reduction neutralization test 50% (PRNT50 ). RESULTS: Six specimens with a high neutralizing titer against wild-type SARS-CoV-2 and three specimens with a low neutralizing titer against wild-type SARS-CoV-2 were chosen for further analysis against VOCs. Four of six high neutralizing titer specimens had a reduced neutralizing capacity against beta VOCs by both neutralization methods. Three of six high neutralizing titer specimens had reduced neutralization capacity against gamma VOCs. CONCLUSIONS: This preliminary data can be used as a justification for limiting the use of first wave plasma products in upcoming clinical trials but cannot be used to speculate on general trends in the immunity of Canadian blood donors to SARS-CoV-2.