Convalescent plasma donors show enhanced cross-reactive neutralizing antibody response to antigenic variants of SARS-CoV-2 following immunization.

BACKGROUND: The therapeutic benefit of convalescent plasma (CP) therapy to treat COVID-19 may derive from neutralizing antibodies (nAbs) to SARS-CoV-2. To investigate the effects of antigenic variation on neutralization potency of CP, we compared nAb titers against prototype and recently emerging strains of SARS-CoV-2, including Delta and Omicron, in CP donors previously infected with SARS-CoV-2 before and after immunization. METHODS AND MATERIALS: Samples were assayed from previously SARS-CoV-2 infected donors before (n = 17) and after one (n = 43) or two (n = 71) doses of Astra-Zeneca or Pfizer vaccinations. Ab titers against Wuhan/wild type (WT), Alpha, Beta, and Delta SARS-CoV-2 strains were determined by live virus microneutralization assay while titers to Omicron used a focus reduction neutralization test. Anti-spike antibody was assayed by Elecsys anti-SARS-CoV-2 quantitative spike assay (Roche). RESULTS: Unvaccinated donors showed a geometric mean titer (GMT) of 148 against WT, 80 against Alpha but mostly failed to neutralize Beta, Delta, and Omicron strains. Contrastingly, high GMTs were observed in vaccinated donors against all SARS-CoV-2 strains after one vaccine dose (WT:703; Alpha:692; Beta:187; Delta:215; Omicron:434). By ROC analysis, reactivity in the Roche quantitative Elecsys spike assay of 20,000 U/mL was highly predictive of donations with nAb titers of ≥1:640 against Delta (90% sensitivity; 97% specificity) and ≥1:320 against Omicron (89% sensitivity; 81% specificity). DISCUSSION: Vaccination of previously infected CP donors induced high levels of broadly neutralizing antibodies against circulating antigenic variants of SARS-CoV-2. High titer donations could be reliably identified by automated quantitative anti-spike antibody assay, enabling large-scale preselection of high-titer convalescent plasma.

How donor selection criteria can be evaluated with limited scientific evidence: lessons learned from the TRANSPOSE project.

BACKGROUND AND OBJECTIVE: Donor selection criteria (DSC) are a vital link in the chain of supply of Substances of Human Origin (SoHO) but are also subject to controversy and differences of opinion. Traditionally, DSC have been based on application of the precautionary principle. MATERIALS AND METHODS: From 2017 to 2020, TRANSPOSE (TRANSfusion and transplantation PrOtection and SElection of donors), a European research project, aimed to identify discrepancies between current DSC by proposing a standardized risk assessment method for all SoHO (solid organs excluded) and all levels of evidence. RESULTS: The current DSC were assessed using a modified risk assessment method based on the Alliance of Blood Operators' Risk-based decision-making framework for blood safety. It was found that with limited or diverging scientific evidence, it was difficult to reach consensus and an international standardized method for decision-making was lacking. Furthermore, participants found it hard to disregard their local guidelines when providing expert opinion, which resulted in substantial influence on the consensus-based decision-making process. CONCLUSIONS: While the field of donation-safety research is expanding rapidly, there is an urgent need to formalize the decision-making process regarding DSC. This includes the need for standardized methods to increase transparency in the international decision-making process and to ensure that this is performed consistently. Our framework provides an easy-to-implement approach for standardizing risk assessments, especially in the context of limited scientific evidence.

Putting the spotlight on donation-related risks and donor safety - are we succeeding in protecting donors?

BACKGROUND AND OBJECTIVE: The European consortium project TRANSPOSE (TRANSfusion and transplantation: PrOtection and SElection of donors) aimed to assess and evaluate the risks to donors of Substances of Human Origin (SoHO), and to identify gaps between current donor vigilance systems and perceived risks. MATERIALS AND METHODS: National and local data from participating organizations on serious and non-serious adverse reactions in donors were collected from 2014 to 2017. Following this, a survey was performed among participants to identify risks not included in the data sets. Finally, participants rated the risks according to severity, level of evidence and prevalence. RESULTS: Significant discrepancies between anticipated donor risks and the collected data were found. Furthermore, many participants reported that national data on adverse reactions in donors of stem cells, gametes, embryos and tissues were not routinely collected and/or available. CONCLUSIONS: These findings indicate that there is a need to further develop and standardize donor vigilance in Europe and to include long-term risks to donors, which are currently underreported, ensuring donor health and securing the future supply of SoHO.

A randomized noninferiority crossover trial of corrected count increments and bleeding in thrombocytopenic hematology patients receiving 2- to 5- versus 6- or 7-day-stored platelets.

BACKGROUND: Bacterial screening offers the possibility of extending platelet (PLT) storage to Day 7. We conducted a noninferiority, crossover trial comparing PLTs stored for 6 or 7 days versus 2 to 5 days. STUDY DESIGN AND METHODS: Stable hematology patients were allocated to receive blocks of 2- to 5- and 6- or 7-day PLTs in random order. The primary outcome was the proportion of successful transfusions during the first block, defined as a corrected count increment (CCI) of more than 4.5 at 8 to 24 hours posttransfusion. RESULTS: Of 122 patients with an evaluable first block, 87 (71%) and 84 (69%) had successful transfusions after 2- to 5- and 6- or 7-day PLTs of mean (SD) ages of 3.8 (1.0) and 6.4 (0.5) days, respectively. Six- or 7-day PLTs were declared noninferior to 2- to 5-day PLTs since the upper confidence interval (CI) limit was less than the predefined noninferiority margin of 10% (95% CI, -14.0% to 9.1%; p = 0.766). Logistic regression analysis gave an adjusted odds ratio of 0.86 (95% CI, 0.47-1.58; p = 0.625). Mean (SD) 8- to 24-hour CCIs were 9.4 (7.9) and 7.7 (7.1) after transfusion with 2- to 5- or 6- or 7-day PLTs (95% CI, -3.31 to 0.03; p = 0.054). The proportions of days with bleeding scores of WHO Grade 2 or higher were 13% (38/297 days) and 11% (32/296 days; 95% CI, -3.2 to 7.2; p = 0.454). Median interval to next PLT transfusion (2 days) was unaffected (95% CI, -10.5 to 5.4; p = 0.531). CONCLUSION: In hematology patients, there was no evidence that 6- or 7-day PLTs were inferior to 2- to 5-day PLTs, as measured by proportion of patients with successful transfusions, bleeding events, or interval to next transfusion.

Selection strategies for newly registered blood donors in European countries.

BACKGROUND: Two selection strategies for newly-registered blood donors are available: a single-visit selection called the standard selection procedure (SSP), and a two-stage selection named predonation and donation screening (PDS). This study reviews the selection strategies for newly-registered donors currently applied in European countries. MATERIAL AND METHODS: We collected data on donor selection procedures, blood donation, laboratory screening and HIV, HCV and HBV positive donors/donations from 2010 to 2013 in 30 European countries by using questionnaires. We grouped the countries according to the applied selection strategy, and for each country, we calculated the 4-year prevalence of confirmed positive results indicating the presence of overall and recent HIV, HCV and HBV infections among first-time and repeat donations and among newly-registered donors. RESULTS: Most of the 24 countries (80%) apply the SSP strategy for selection of newly-registered donors. Twenty-two countries (73.3%) employ a nucleic acid amplification testing in addition to the mandatory serological screening. The survey confirms a higher overall prevalence of HIV, HCV and HBV infections among first-time donations and newly-registered donors than among repeat donations. In contrast, the prevalence of recently acquired HIV and HCV infections was lower among first-time donations and newly-registered donors than among repeat donations, but higher for recent HBV infections (6.7/105 vs 2.6/105 in the SSP setting and 4.3/105 vs 0.5/105 in one country using PDS). The relatively low numbers of infected donors selected by PDS impeded accurate assessment of the prevalence of recent infections in first-time donations. DISCUSSION: The data from European countries provide inconclusive evidence that applying PDS reduces the risk of donations being made in the diagnostic window of first-time donors. The impact of PDS on the risk of window-period donations and blood donor management needs further investigation.

Risks and side effects of therapy with plasma and plasma fractions.

Transfusion of plasma can lead to adverse reactions or events. Immune-mediated reactions are most common--these include allergic and anaphylactic reactions, transfusion-related acute lung injury (TRALI) and haemolysis. They can range in severity from mild to fatal. Fluid overload and citrate toxicity can occur after rapid or massive transfusion. In developed countries, microbial transmission rates are low because of donor selection and testing. Pathogen reduction processes can be applied to either single-unit components (methylene blue) or plasma pools (solvent-detergent). They have the unwanted effect of reducing some coagulation factors but reduce viral transmission risk even further. Reactions associated with plasma products or fractions also include allergic reactions, although TRALI is rare. Viral transmission risk is very low because of the use of two independent viral inactivation steps. Different products have particular specific unwanted effects: intravenous immunoglobulin has been associated with thrombotic events, renal toxicity and aseptic meningitis; coagulation factors are associated with development of inhibitors and thrombotic events. The risk of transmission of variant Creutzfeldt-Jakob disease in both plasma components and pooled plasma products is as yet unknown. If anything, the low titre of prion infectivity in the blood of an infected individual (approximately 10 infectious units/ml) will be massively diluted by the thousands of units of plasma in the pool. Subsequent manufacturing processes also remove prions from the final product.

Focus on fresh frozen plasma - facilitating optimal management of bleeding through collaboration between clinicians and transfusion specialists on component specifications.

BACKGROUND: A symposium on plasma for direct clinical use was held in September 2015 by the European directorate for the quality of medicines and healthcare (EDQM) in order to consider changes to the Council of Europe guide to the preparation, use and quality assurance of blood components monographs on plasma components. METHODS: The programme reviewed use of plasma in various settings, novel components, adverse reactions, manufacturing and quality monitoring issues. RESULTS: The main requirement identified was that plasma should be made available to support early transfusion in the trauma/massive haemorrhage setting. Further guidance on component manufacturing and reviewing of quality monitoring requirements will also be addressed. CONCLUSION: A working group has been established to review component monographs and other advice in the guide relating to plasma components, with the aim of providing optimal components to support clinical management of patients requiring plasma.

Risks of fresh frozen plasma and platelets.

Both fresh frozen plasma (FFP) and platelets are heavily used in massive transfusion. Although FFP can partially correct abnormal coagulation, a recent systematic review revealed no randomized trials showing clinical benefit. Although the overall risks of FFP and platelets are low, they are the least safe blood components, due to immunologic reactions such as allergy/anaphylaxis, transfusion-related acute lung injury (TRALI) and hemolysis due to anti-A or anti-B if transfused across ABO groups. TRALI, an acute syndrome of dyspnoea, hypoxia and pulmonary 'white-out' is now a major cause of transfusion-related death. Since it is usually triggered by donor HLA antibodies, selecting non- immune donors for FFP production may be beneficial. For platelet components, risks may be reduced by platelet additive solution, allowing removal of 70% of plasma. Platelets have the additional hazard of bacterial contamination, with donor skin the predominant source. Improved arm cleansing, divert pouches for the first 30-50 mL blood and bacterial screening have been adopted internationally. Virus risks are now vanishingly low, although new agents e.g. West Nile virus can still appear. Pathogen reduction for FFP is now well established in Europe, with solvent detergent and methylene blue methods licensed, and the psoralen amotosalen in trial. Loss of clotting factors and natural anti-coagulants are recognized side effects. Amotosalen is also licensed for platelet concentrates, with the added benefit of bacterial killing. In the UK, concern regarding vCJD has led to importation of US FFP for children.

Reference intervals for serum proteins: similarities and differences between adult Caucasian and Asian Indian males in Yorkshire, UK.

The aim of this study was to investigate similarities and differences in the distribution of serum concentrations of nine proteins in two racial groups (Caucasian and Asian Indian) of adult males living in the same geographical area (Leeds, Bradford, UK) for at least two generations. This is part of a larger study to determine the need for separating reference intervals for racial and ethnic groups worldwide. The distributions of concentrations for all proteins evaluated in the Indians fit In-Gaussian distributions, indicating probable homogeneity. However, for the Caucasians, the distributions for alpha1-antitrypsin and possibly haptoglobin were not In-Gaussian. In the former case, this is undoubtedly due to the number of Caucasians with lower-concentration phenotypes (Pi MS and MZ). Although haptoglobin differences may be due to genetic variants as well, this is not a complete explanation. In addition, the Indians have lower serum concentrations of orosomucoid (alpha1-acid glycoprotein), as has been reported by others. It is apparent that for some proteins, including alpha1-antitrypsin, orosomucoid, and possibly haptoglobin, the populations show differences that require the use of separate reference intervals. In addition to genetic influences, environmental differences cannot be ruled out as partial causes for some of the differences noted.