Plasmapheresis Donors Research Articles

Association of regular plasmapheresis donation with serum protein and electrolyte levels: a multicentre cross-sectional study in China

BackgroundChina’s plasmapheresis donation policy differs from that of Western countries. The association between regular plasmapheresis donation and donor health in China is still unknown.ObjectivesTo investigate the association of regular plasmapheresis...

Repeated apheresis donations cause important iron deficiency in male Japanese donors.

In Japan, apheresis donation of plasma is allowed to a maximum of 24 times a year, and plateletpheresis are counted as two plasmapheresis donations. Diversion of the initial blood flow is conducted for all donations, and additionally, blood remaining in apheresis machine circuit is lost. Here, we aimed to investigate on the health impact of frequent apheresis donations, as measured by the serum ferritin (sFer). A total of 538 male apheresis donors and 538 age-matched whole blood (WB) donors, who gave informed consent to join the study, were enrolled. sFer were compared, according to age. Another group of 19 apheresis donors were followed during four consecutive donations. About half (48%) of repeat male apheresis donors had iron deficiency (sFer < 26 ng/mL), compared with lower rates (13.9%) among male WB donors. It was evident in all age groups, except for teenagers, possibly because of the lower number of donations. Follow-up of the 19 donors for 4 months revealed a progressive decrease in sFer. Blood remaining in the apheresis machine circuit and diversion of the initial blood flow have been implicated in iron deficiency for many years. Taking the present results, the manufacturer of apheresis equipment was requested to improve it to allow rinseback of the remaining blood, which was achieved only for plateletpheresis. Until further improvement, plasmapheresis frequency was reduced to 12 times a year. Additional measures, such as oral supplementation of iron, need to be considered.

A Cross-Sectional Study of Measles-Specific Antibody Levels in Australian Blood Donors-Implications for Measles Post-Elimination Countries.

Passive immunisation with normal human immunoglobulin (NHIG) is recommended as post-exposure prophylaxis (PEP) for higher-risk measles contacts where vaccination is contraindicated. However, the concentration of measles-specific antibodies in NHIG depends on antibody levels within pooled donor plasma. There are concerns that measles immunity in the Australian population may be declining over time and that blood donors' levels will progressively decrease, impacting levels required to produce effective NHIG for measles PEP. A cross-sectional study of Australian plasmapheresis donors was performed using an age-stratified, random sample of recovered serum specimens, collected between October and November 2019 (n = 1199). Measles-specific IgG antibodies were quantified by ELISA (Enzygnost anti-measles virus IgG, Siemens), and negative and equivocal specimens (n = 149) also underwent plaque reduction neutralisation testing (PRNT). Mean antibody levels (optical density values) progressively decreased from older to younger birth cohorts, from 2.09 [±0.09, 95% CI] to 0.58 [±0.04, 95% CI] in donors born in 1940-1959 and 1990-2001, respectively (p < 0.0001). This study shows that mean measles-specific IgG levels are significantly lower in younger Australian donors. While current NHIG selection policies target older donors, as younger birth cohorts become an increasingly larger proportion of contributing donors, measles-specific antibody concentrations of NHIG will progressively reduce. We therefore recommend monitoring measles-specific antibody levels in future donors and NHIG products in Australia and other countries that eliminated measles before the birth of their youngest blood donors.

New tatt? We're ok with that! Relaxing the tattoo deferral for plasmapheresis donors maintains safety and increases donations.

Tattooing is one of the leading donor deferral reasons in Australia. Until September 2020, donors were deferred from all donation types for 4 months after a tattoo. At this time, our guideline changed such that donations of plasma for further manufacture were accepted immediately, provided the tattoo was administered in a licensed or regulated Australian establishment. We examined the effects of this change. Donors with a tattoo deferral in the 2 years before or after the guideline change were identified and followed up until 3 November 2022. Between the two periods, we compared blood-borne virus (BBV) incidence, donor return, and the number of donors and donations regained after deferral. The incidence of BBV infection in donors after a tattoo deferral was zero in both periods. To exceed a residual risk of 1 in 1 million for hepatitis C virus, 190 donors would need to be infected yearly from a tattoo. Donors returned to donate significantly faster after the change (median return 85 days compared with 278 days). An extra 187 donations per 10,000 person-years of observation were gained, yielding a total of 44,674 additional plasma donations nationally 0-4 months after getting a tattoo. Allowing plasma donations immediately post-tattoo resulted in a substantial donation gain with no adverse safety effect. Lifeblood subsequently reduced the deferral for transfusible component donations to 7 days for tattoos in Australian licensed/regulated establishments.

The risks of low hemoglobin deferral in a large retrospective cohort of plasmapheresis donors and the influence factors of return for a subsequent donation in China

Background and ObjectivesSome plasmapheresis donors were deferred from donating when they did not meet hemoglobin (Hb) criteria. The purpose of this retrospective analysis was to explore the characteristics of the low hemoglobin deferral (LHD) in plasmapheresis donors and identify at-risk donors of LHD, so as to enhance donor safety and improve donation service satisfaction of the plasmapheresis centers. Materials and MethodsThis multi-center survey was carried out from 2018 until 2020 on all plasmapheresis donors from 18 plasmapheresis centers in three provinces of China. Donor demographics and information were retrieved. A Cochran-Mantel-Haenszel Method was used to test the association between LHD and risk factors while controlling for difference geographic information of donors. Logistic regression analysis was used to explore the influence factors of return for a subsequent donation. ResultsA total of 497,039 participants were included. The female LHD rate was 0.15%, and male LHD rate was 0.01%. The most important risk factor for predicting the possibility of LHD in females was age between 41 to 50 years old. Donation in the winter was a protective factor from LHD. The number of donations in the previous 12 months were more likely to meet the Hb parameters and continue to donate. ConclusionsWe need to focus on premenopausal women, increase recruitment in winter and take necessary interventions in other seasons. The LHD donors who had more donations in previous 12 months, the more likely they were to meet the Hb conditions again and continue to donate.

Risk prediction of iron deficiency for plasmapheresis donors in China: Development and validation of a prediction model.

The present study aims to evaluate the iron stores in plasmapheresis donors and develop and validate an iron deficiency (ID) risk prediction model for plasmapheresis donors with potential or existing ID. We assessed plasmapheresis donors' serum ferritin (SF) and haemoglobin (Hb) levels. The candidate factors showing significant differences in the multivariate logistic regression analysis were used to establish a risk prediction scoring system. The participants were divided into a training cohort and an internal validation cohort in a 7:3 ratio. Additional plasmapheresis donors from a different station were recruited for external validation. The SF levels in both male and female donors in the high-frequency group were significantly lower than those of new donors (male: p < 0.001; female: p = 0.008). The prevalence of ID in female regular donors with a high frequency was significantly higher than that in new donors (33.1% vs. 24.6%; odds ratio = 1.209 [95% CI: 1.035-1.412]). Donation frequency, age, Hb, body mass index and being pre-menopausal were identified as independent risk factors for ID (p < 0.05). The developed model exhibited good discrimination ability (area under the receiver operating characteristic curve >0.7) and calibration (p > 0.05) in development, internal validation cohorts and external validation cohorts. A higher donation frequency has been associated with reduced SF levels and an increased risk of ID in women. The developed ID risk prediction model demonstrates moderate discriminative power and good model fitting, suggesting its potential clinical utility.

Safety and protection of plasma donors: A scoping review and evidence gap map.

As part of a large-scale project to safely increase plasma collection in Europe, the current scoping review identifies the existing evidence (gaps) on adverse events (AEs) and other health effects in plasmapheresis donors, as well as factors that may be associated with such events/effects. We searched six databases and three registries. Study characteristics (publication type, language, study design, population, outcomes, associated factors, time of assessment, duration of follow-up, number and frequency of donations, convalescent plasma [y/n], setting and location) were synthesized narratively and in an interactive evidence gap map (EGM). Ninety-four research articles and five registrations were identified. Around 90% were observational studies (57 controlled and 33 uncontrolled), and most of them were performed in Europe (55%) or the United States (20%). Factors studied in association with donor health included donor characteristics (e.g., sex, age) (n = 27), cumulative number of donations (n = 21), donation frequency (n = 11), plasma collection device or programme (n = 11), donor status (first time vs. repeat) (n = 10), donation volume per session (n = 8), time in donation programme (n = 3), preventive measures (n = 2) or other (n = 9). The current scoping review provides an accessible tool for researchers and policymakers to identify the available evidence (gaps) concerning plasmapheresis donation safety. Controlled prospective studies with long-term donor follow-up are scarce. Furthermore, additional experimental studies comparing the health effects of different donation frequencies are required to inform a safe upper limit for donation frequency.

P‐BB‐41 | Humoral Response to COVID‐19 Vaccination in Frequent Plasmapheresis Donors

P‐BB‐41 | Humoral Response to COVID‐19 Vaccination in Frequent Plasmapheresis Donors

Effect of Plasma Unit Weight and Donor Sex on Post-Donation Citrate Level: An Experimental Study on Plasmapheresis Donors

Introduction: Plasmapheresis donation is considered safe and well tolerated, although long-term effects need to be clarified. The volumes of anticoagulant (ACD-A) used are variable and depend primarily on hematocrit (HCT), total blood processed, amount of plasma collected, and donor characteristics. To elucidate the effect of the plasma unit weight setting on plasmapheresis efficiency and ACD-A distribution, we enrolled male donors undergoing a controlled apheresis process donating 700 g and 720 g in two different sessions. In parallel, we investigated a possible effect of sex, recruiting women donating 700 g of plasma. Methods: The study was conducted on men donating 720 g and (12 months later) 700 g of plasma, and on women donating 700 g of plasma. The main outcomes were pre-/post-donation delta (Δ) citrate concentration in donor plasma and ACD-A reinfused to the donor. Information concerning the annual check-up and the procedure was also collected. Intergroup comparisons (men donating 720 g vs. men donating 700 g and men vs. women both donating 700 g) and intragroup associations with donor and procedural characteristics were reported. Results: With the procedure set at 720 g, the machine processed around 44 mL more whole blood to collect 20 g more plasma, and 720 g donors received around 12 mL more anticoagulant than 700 g donors. Accordingly, Δ citrate concentration was 1.5 times higher (12 μm), with a greater variability observed for 720 g donations. Citrate concentration in the plasma unit was lower in the 720 g group, although not significantly. Comparing outcomes between women and men donating 700 g, we observed higher (and highly variable) Δ citrate and reinfused ACD-A in women, accompanied by lower anticoagulant levels in the unit. Increased Δ citrate is inversely associated with HCT and age in men and with HCT and triglycerides in women. Reinfused ACD-A correlates with HCT in women but not in men. Conclusion: Unit weight setting and sex influence an ACD-A shift from the estimated values toward an increased reinfusion to donor. In parallel, we observed an impact of age and sex on post-donation citrate metabolism. Altogether, these elements should be taken into account for the development of tailored approaches aimed at maintaining similar safety profiles for all donors using different plasmapheresis settings.

Review and assessment of the donor safety among plasma donors.

Review and assessment of the donor safety among plasma donors.

Source Plasma Donation: The Experience of the Iranian Blood Transfusion Organization.

Background: A declining need for red blood cells coupled with strengthening demand for plasma-derived medicines has led to a strong focus on moving whole blood donors to plasmapheresis. The purpose of this study was to evaluate the four-year policies of the Iranian Blood Transfusion Organization (IBTO) in terms of plasmapheresis recruitment of first-time donors and its effect on plasmapheresis outcome. Materials and Methods: Plasmapheresis data related to 16 centers from 2016 to 2019 was obtained from IBTO software. This information includes; (1) blood donation number, (2) plasmapheresis donation number, (3) number of plasmapheresis donors, (4) plasmapheresis donor demographic data, (5) plasmapheresis donor status, (6) frequency of plasma donation for each donor, (7) volume of plasma and (8) the prevalence of transfusion-transmissible infections (TTIs) in plasmapheresis donors. Results:The result of this study demonstrated thatplasmapheresis collection centers have recruited 85,515 (91%) first-time and 8,595(9%) regular and repeated donors from 2016 to 2019 years. Plasmapheresis to blood donation index was increased from 0.2% in 2016 to 4.9% in 2019. The mean donation number was 2 times per year. The trend of the yearly Whole Blood Donation (WBD) Index decreased from 26.69 to 24.11/1000 for the general population. The total volume of collected source plasma was 49,203 liters during this period. However, 46,000 liters of recovered plasma were decreased due to less WBD. Furthermore, the results indicated that the prevalence of HCV was significantly higher in first-time donors compared to repeated and regular donors (P = 0.000). Conclusion: It is concluded that during four years, the net volume of plasma did not increase and plasmapheresis led to reducing WBD in our country. Moreover, first-time plasmapheresis donors can be associated with challenges such as increasing screening costs and compromising the safety of plasma resources. Therefore IBTO decided to stop the project and focus on its main role to prepare safe and sufficient blood components through WB collection and also single donor platelet and concurrent plasma by plateletpheresis.

Single Donor Plasmapheresis for COVID-19: An Experience from a Tertiary Care Hospital Based Blood Centre

Introduction: Corona Virus Disease-2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) became a global health problem since December 2019. No single treatment was found to be effective against COVID-19. Transfusion of COVID Convalescent Plasma (CCP) was found to be a useful and logistically feasible therapeutic strategy in COVID-19. Aim: To study the feasibility of single donor plasmapheresis for COVID-19, to analyse statistical significance of clinico- demographical data and biochemical parameters of convalescent plasmapheresis donors and to further study the adverse reactions and technical problems that occurred during the procedure of single donor plasmapheresis. Materials and Methods: A prospective observational study was carried out over a period of 10 months from June 2020 to March 2021. The study included 235 screened donors and 50 procedures for single donor plasmapheresis (SDPs). Donors were selected as per the standard criteria given by Indian Council of Medical Research (ICMR). All plasmapheresis procedures were performed on an automated blood cell separator. The results were tabulated and statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) software. Results: Out of 235 prospective CCP donors, 164 (69.78%) were found eligible. The causes of non eligibility donors were unwillingness to donate, absence of SARS-CoV-2 antibody, Transfusion Transmitted Disease (TTD) positivity, and improper haematological parameters. Actual plasma donations were carried out in 50 (21.27%) eligible donors. Therapeutically needed amount of CCP (400 mL) could be collected from most of the donors. Adverse reactions were seen in 4 (8%) donors. Conclusion: Adequate amount of CCP could be collected by single donor plasmapheresis with satisfactory technical support. The procedure was well accepted by the prescreened donors with minimum adverse reactions.

Absence of correlation between ABO Rh(D) blood group and neutralizing antibody titers in SARS-CoV-2 convalescent plasma donors.

Several studies have described associations between ABO blood group and SARS-CoV-2 infection severity in hospitalized patients where group A individuals are over-represented and group O individuals may have a lower infection rate. In convalescent individuals, group B blood donors have higher neutralizing SARS-CoV-2 antibody titers. We analyzed whether there was any correlation of ABO Rh(D) blood group with SARS-CoV-2 infection and with neutralizing antibodies in Australian convalescent plasma (CP) donors. ABO Rh(D) distribution and demographics of CP donors (n=765) were compared with the total blood donor panel (n=488,028), plasmapheresis donors (n=203,176) and whole blood donors (n=282,437) from 2020. The presence of neutralizing antibodies in CP donors was measured using the Vero E6 cell microneutralization assay. The distribution of ABO group in CP donors compared to the total donor panel was not significantly different (p=.177). There were significantly more group AB donors in the plasmapheresis subset (p=.005) and group O individuals were over-represented in the whole blood donor subset (p < .0001). There was no significant difference in neutralizing antibody levels among CP donors with differing ABO blood groups (p=.872). ABO Rh(D) blood group distribution was not found to be significantly different between convalescent plasma donors and general blood donors in our large sample group. Inherent blood donor selection biases associated with clinical demand accounted for some differences within CP donors. The levels of SARS-CoV-2 neutralizing antibodies were also not significantly associated with ABO Rh(D) group.

Hepatitis B seroconversion revisited: new insights into the natural history of acute hepatitis B virus (HBV) infection from quantitative and highly sensitive assays and novel biomarkers

BackgroundHepatitis B virus (HBV) serum markers during typical acute self-limited infection are usually depicted as a composite of traditional HBV markers. The current study updates and expands our knowledge of acute hepatitis B with quantitative molecular and serological data on longitudinal samples from five plasmapheresis donors with acute HBV.Methods137 longitudinal samples from five plasmapheresis donors with acute HBV were tested, four with self-limited infection and one who developed persistent infection. Testing included quantitative hepatitis B surface antigen (HBsAg), antibodies to HBV antigens, quantitative HBV e antigen (HBeAg), HBV DNA, quantitative HBV core-related antigen (HBcrAg), the highly sensitive ARCHITECT HBsAg NEXT (HBsAgNx) assay, and a quantitative research assay for HBV pregenomic RNA (pg RNA).ResultsPeak levels of HBV DNA and HBsAg differed by several orders of magnitude among the panels (2.2 × 105–2.7 × 109 IU/ml for HBV DNA and 7.9–1.1 × 105 IU/ml for HBsAg). HBsAg levels peaked an average of 2.8 days after the HBV DNA peak. The overall duration of observed HBsAg positivity was increased by the more sensitive HBsAgNx assay compared to the quantitative assay in four panels. Intermittently detectable low-level HBV DNA was observed after HBsAg loss in three panels. Peak HBeAg levels occurred 2–20 days after the DNA peak and ranged from 1.1 to 4.5 × 103 IU/ml. In four panels with resolution of infection, anti-HBs levels indicating immunity (≥ 10 mIU/ml) were detected 19–317 days after the HBV DNA peak. Maximum HBcrAg concentrations ranged from 1 × 105 to > 6.4 × 106 U/ml and correlated with HBeAg values (R2 = 0.9495) and with HBV DNA values (R2 = 0.8828). Peak pgRNA values ranged from 1.6 × 103 to 1.4 × 108 U/ml and correlated with HBV DNA (R2 = 0.9013).ConclusionTraditional and new/novel HBV biomarkers were used to generate molecular and serological profiles for seroconversion panels spanning the early to late phases of acute HBV. Seroconversion profiles were heterogeneous and may be instructive in appreciating the spectrum of acute profiles relative to the typical composite representation.

Seroprevalence of SARS-CoV-2 among potential convalescent plasma donors and analysis of their deferral pattern: Experience from tertiary care hospital in western India.

Background and objectivesSeroprevalence estimation of COVID-19 is quite necessary for controlling the transmission of SARS-CoV-2 infection. Seroprevalence rate in recovered COVID-19 patients help us to identify individual with anti-SARS-CoV-2 antibodies and its protective nature. The objective of present study was to evaluate seroprevalence of SARS-CoV-2 among potential convalescent plasma donors and analysis of their deferral reasons.Materials and methodsA total 400 potential convalescent plasma donors were enrolled over five-month period for this prospective study. Inclusion criteria were lab confirmed COVID-19 recovered patients and 14 days of symptoms free period. All prospective plasmapheresis donors were tested for IgG SARS-CoV-2 antibody through chemiluminescent microparticle immunoassay, CBC, serum protein, blood grouping along with other required test for normal blood donation as per Drugs & Cosmetics Act. After pre donation testing and medical examination if donor was found to be ineligible for plasmapheresis was deferred. Seroprevalence rate was calculated by positive IgG antibody test results among the potential plasma donors.ResultsSeroprevalence rate was 87% for IgG SARS-CoV-2 antibodies in prospective convalescent plasma donors (recovered COVID-19 patients). There was no significant difference in seroprevalence rate between different sub-groups with respect to gender, age, blood groups, Rh factor, mode of treatment, day of Ab testing and repeat plasma donation. Most common reason for their deferral was absent IgG SARS-CoV-2 antibodies (13%) followed by absenteeism of eligible screen donors (6.7%), low Hb (1.7%) and poor veins for plasmapheresis (1.7%). Till five-month study period none of the plasmapheresis develop symptoms of reinfection with COVID-19.ConclusionIn all, 13% recovered patients did not develop IgG antibodies after SARS-CoV-2 infection. SARS-CoV-2 IgG antibodies persist for quite some time and are protective against reinfection. More long-term serology studies are needed to understand better antibody response kinetics and duration of persistence of IgG antibodies.

Characteristics of coronavirus disease 19 convalescent plasma donors and donations in the New York metropolitan area

BackgroundConvalescent plasma (CP) is an important initial treatment in pandemics and the New York (NY) metropolitan area is likely to remain a hotspot for collection and distribution of such units. This study reports characteristics of coronavirus disease 19 CP (CCP) donors and their donations to the New York Blood Center (NYBC).Study design and methodsAll CCP data from our first day of collection on March 26th through July 7th, 2020 are included in this retrospective analysis. Donor and donation data were extracted from NYBC electronic databases. SARS‐CoV‐2 antibody testing was initially performed by the NY State Department of Health, and later by NYBC using Ortho and Abbott platforms.ResultsCCP donor age and ABO distributions were consistent with reported lower COVID‐19 susceptibility in O blood types. CCP versus whole blood donors had similar on‐site deferrals, but higher post‐donation deferral rates. CCP versus routine plasmapheresis donations had higher vasovagal reactions but similar product rejection rates. Changes in antibody (Ab) test platforms resulted in significant changes in the percent of donors regarded as antibody positive. Donor correlates with higher anti‐spike total Ig S/CO ratios were Hispanic ethnicity, overweight body mass index, and longer symptom duration; and with higher anti‐nucleocapsid IgG S/CO ratios were male gender, older age, Hispanic ethnicity, and fewer days between symptom onset and first donation.DiscussionWe identify donor characteristics not previously reported to correlate with Ab titer. Our analysis should assist with donor outreach strategies, blood center operating logistics, and recruitment of high titer donors.

Seroprevalence of SARS-CoV-2-specific antibodies in Sydney after the first epidemic wave of 2020.

ObjectivesTo estimate SARS‐CoV‐2‐specific antibody seroprevalence after the first epidemic wave of coronavirus disease 2019 (COVID‐19) in Sydney.Setting, participantsPeople of any age who had provided blood for testing at selected diagnostic pathology services (general pathology); pregnant women aged 20–39 years who had received routine antenatal screening; and Australian Red Cross Lifeblood plasmapheresis donors aged 20–69 years.DesignCross‐sectional study; testing of de‐identified residual blood specimens collected during 20 April – 2 June 2020.Main outcome measureEstimated proportions of people seropositive for anti‐SARS‐CoV‐2‐specific IgG, adjusted for test sensitivity and specificity.ResultsThirty‐eight of 5339 specimens were IgG‐positive (general pathology, 19 of 3231; antenatal screening, 7 of 560; plasmapheresis donors, 12 of 1548); there were no clear patterns by age group, sex, or location of residence. Adjusted estimated seroprevalence among people who had had general pathology blood tests (all ages) was 0.15% (95% credible interval [CrI], 0.04–0.41%), and 0.29% (95% CrI, 0.04–0.75%) for plasmapheresis donors (20–69 years). Among 20–39‐year‐old people, the age group common to all three collection groups, adjusted estimated seroprevalence was 0.24% (95% CrI, 0.04–0.80%) for the general pathology group, 0.79% (95% CrI, 0.04–1.88%) for the antenatal screening group, and 0.69% (95% CrI, 0.04–1.59%) for plasmapheresis donors.ConclusionsEstimated SARS‐CoV‐2 seroprevalence was below 1%, indicating that community transmission was low during the first COVID‐19 epidemic wave in Sydney. These findings suggest that early control of the spread of COVID‐19 was successful, but efforts to reduce further transmission remain important.

Development of a SARS-CoV-2 Total Antibody Assay and the Dynamics of Antibody Response over Time in Hospitalized and Nonhospitalized Patients with COVID-19.

Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infections often cause only mild disease that may evoke relatively low Ab titers compared with patients admitted to hospitals. Generally, total Ab bridging assays combine good sensitivity with high specificity. Therefore, we developed sensitive total Ab bridging assays for detection of SARS-CoV-2 Abs to the receptor-binding domain (RBD) and nucleocapsid protein in addition to conventional isotype-specific assays. Ab kinetics was assessed in PCR-confirmed, hospitalized coronavirus disease 2019 (COVID-19) patients (n = 41) and three populations of patients with COVID-19 symptoms not requiring hospital admission: PCR-confirmed convalescent plasmapheresis donors (n = 182), PCR-confirmed hospital care workers (n = 47), and a group of longitudinally sampled symptomatic individuals highly suspect of COVID-19 (n = 14). In nonhospitalized patients, the Ab response to RBD is weaker but follows similar kinetics, as has been observed in hospitalized patients. Across populations, the RBD bridging assay identified most patients correctly as seropositive. In 11/14 of the COVID-19-suspect cases, seroconversion in the RBD bridging assay could be demonstrated before day 12; nucleocapsid protein Abs emerged less consistently. Furthermore, we demonstrated the feasibility of finger-prick sampling for Ab detection against SARS-CoV-2 using these assays. In conclusion, the developed bridging assays reliably detect SARS-CoV-2 Abs in hospitalized and nonhospitalized patients and are therefore well suited to conduct seroprevalence studies.

Frequent platelet donation is associated with lymphopenia and risk of infections: A nationwide cohort study.

BackgroundRecently, plateletpheresis donations using a widely used leukoreduction system (LRS) chamber have been associated with T‐cell lymphopenia. However, clinical health consequences of plateletpheresis‐associated lymphopenia are still unknown.Study Design and MethodsA nationwide cohort study using the SCANDAT3‐S database was conducted with all platelet‐ and plasmapheresis donors in Sweden between 1996 and 2017. A Cox proportional hazards model, using donations as time‐dependent exposures, was used to assess the risk of infections associated with plateletpheresis donations using an LRS chamber.ResultsA total of 74 408 apheresis donors were included. Among donors with the same donation frequency, plateletpheresis donors using an LRS chamber were at an increased risk of immunosuppression‐related infections and common bacterial infections in a dose‐dependent manner. While very frequent donors and infections were rare in absolute terms resulting in wide confidence intervals (CIs), the increased risk was significant starting at one‐third or less of the allowed donation frequency in a 10‐year exposure window, with hazard ratios reaching 10 or more. No plateletpheresis donors that used an LRS chamber experienced a Pneumocystis jirovecii, aspergillus, disseminated mycobacterial, or cryptococcal infection. In a subcohort (n = 42), donations with LRS were associated with low CD4+ T‐cell counts (Pearson's R = −0.41; 95% CI, − 0.63 to −0.12).ConclusionFrequent plateletpheresis donation using an LRS chamber was associated with CD4+ T‐cell lymphopenia and an increased risk of infections. These findings suggest a need to monitor T‐lymphocyte counts in frequent platelet donors and to conduct future investigations of long‐term donor health and for regulators to consider steps to mitigate lymphodepletion in donors.

Long-term return and donation pattern of those who begin donating at different ages: A retrospective cohort analysis of blood donors in Australia.

This study compared the likelihood of return to donate and donation rate ratio by age of donors at their first donation when followed up to 12 years. Donation history of two cohorts of first-time donors (those donating in 2007 and 2013) was extracted until March 2019 from Australian Red Cross Lifeblood's national database. Poisson regression analyses compared donor return and negative-binomial regression estimated the rate ratio of donations. A total of 120 469 and 95 381 donors were included in the 2007 and 2013 cohorts, respectively. Compared to donors aged 20-24 years, the likelihood of return in both cohorts increased consistently as age at first donation increased from 30-years and above. Average number of whole-blood and plasmapheresis donations increased as the age at first donation increased from 30-years onward. The whole-blood donation rate was highest for donors ≥60 years, while plasmapheresis donation rate was highest for donors aged 50-59 years. These patterns were largely consistent when stratified by sex. To continuously ensure the short- to mid-term sufficiency of blood supply in Australia, targeted recruitment of donors aged 30-years and above may be considered, however its feasibility and impact should be explored further given relatively smaller proportion of new donors are middle-aged and older under current policies. Future studies with a longer follow-up period are needed to examine whether the frequency of donation among those who start donating at a younger age increases later in their life when they are 30-years or over.