Simple prediction of COVID-19 convalescent plasma units with high levels of neutralization antibodies.

Hyperimmune convalescent COVID-19 plasma (CCP) containing anti-SARS-CoV-2 neutralizing antibodies (NAbs) was proposed as a therapeutic option for patients early in the new coronavirus disease pandemic. The efficacy of this therapy depends on the quantity of neutralizing antibodies (NAbs) in the CCP units, with titers ≥ 1:160 being recommended. The standard neutralizing tests (NTs) used for determining appropriate CCP donors are technically demanding and expensive and take several days. We explored whether they could be replaced by high-throughput serology tests and a set of available clinical data. Our study included 1302 CCP donors after PCR-confirmed COVID-19 infection. To predict donors with high NAb titers, we built four (4) multiple logistic regression models evaluating the relationships of demographic data, COVID-19 symptoms, results of various serological testing, the period between disease and donation, and COVID-19 vaccination status. The analysis of the four models showed that the chemiluminescent microparticle assay (CMIA) for the quantitative determination of IgG Abs to the RBD of the S1 subunit of the SARS-CoV-2 spike protein was enough to predict the CCP units with a high NAb titer. CCP donors with respective results > 850 BAU/ml SARS-CoV-2 IgG had a high probability of attaining sufficient NAb titers. Including additional variables such as donor demographics, clinical symptoms, or time of donation into a particular predictive model did not significantly increase its sensitivity and specificity. A simple quantitative serological determination of anti-SARS-CoV-2 antibodies alone is satisfactory for recruiting CCP donors with high titer NAbs.

Jazbec K ，Jež M ，Žiberna K ，Mali P ，Ramšak Ž ，Potokar UR ，Kvrzić Z ，Černilec M ，Gracar M ，Šprohar M ，Jovanovič P ，Vuletić S ，Rožman P ... -  《Virology Journal》

Screening for SARS-CoV-2 antibodies in convalescent plasma in Brazil: Preliminary lessons from a voluntary convalescent donor program.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CCP) collection began in two Brazilian hospitals for treatment of severe/critical patients. Mild/moderate COVID-19 convalescents were selected as CCP donors after reverse transcription polymerase chain reaction (RT-PCR) confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and absence of symptoms for ≥14 days plus (a) age (18-60 years), body weight greater than 55 kg; (b) immunohematological studies; (c) no infectious markers of hepatitis B virus, hepatitis C virus, human immunodeficiency virus, human T-lymphotropic virus-1/2, Chagas and syphilis infection; (d) no HLA antibodies (multiparous); (e) second RT-PCR (nasopharyngeal swab and/or blood) negativity; (f) virus neutralization test (cytopathic effect-based virus neutralization test neutralizing antibody) and anti-nucleocapsid protein SARS-CoV-2 IgM, IgG, and IgA enzyme-linked immunosorbent assays. Among 271 donors (41 females, 230 males), 250 presented with neutralizing antibodies. Final RT-PCR was negative on swab (77.0%) or blood (88.4%; P = .46). Final definition of RT-PCR was only defined at more than 28 days after full recovery in 59 of 174 (33.9%) RT-PCR -ve, and 25/69 RT-PCR +ve (36.2%; 13 between 35 and 48 days). Neutralizing antibody titers of 160 or greater were found in 63.6%. Correlation between IgG signal/cutoff of 5.0 or greater and neutralizing antibody of 160 or greater was 82.4%. Combination of final RT-PCR -ve with neutralizing antibody ≥160 was 41.3% (112/271). Serial plasma collection showed decline in neutralizing antibody titers and IgA levels (P < .05), probably denoting a "golden period" for CCP collection (≤28 days after joining the program); IgA might have an important role as neutralizing antibody. Donor's weight, days between disease onset and serial plasma collection, and IgG and IgM levels are important predictors for neutralizing antibody titer. RT-PCR +ve cases are still detected in 36.2% within 28 to 48 days after recovery. High anti-nucleocapsid protein IgG levels may be used as a surrogate marker to neutralizing antibody.

Wendel S ，Kutner JM ，Machado R ，Fontão-Wendel R ，Bub C ，Fachini R ，Yokoyama A ，Candelaria G ，Sakashita A ，Achkar R ，Hamerschlak N ，Scuracchio P ，Amaral M ，Dal Ben M ，Araujo D ，Soares C ，Camargo A ，Kallás E ，Durigon E ，Reis LF ，Rizzo LV ... -  《-》

Surrogate test performance for SARS-CoV-2 neutralizing antibodies (nAbs) for convalescent plasma (CCP): How useful could they be?

COVID-19 high-titer CCP selection is a concern, because neutralizing antibody (nAb) testing requires sophisticated labs and methods. Surrogate tests are an alternative for measuring nAb levels in plasma bags, including those that are pathogen-reduced. We studied a panel consisting of 191 samples from convalescent donors tested by nAb (CPE-VNT), obtained from 180 CCP donations (collection: March 20-January 21) and 11 negative controls, with a total of 80 and 111 serum and plasma samples (71 amotosalen/UV treated), with nAb titers ranging from negative to 10,240. Samples were blindly tested for several surrogates: one anti-RBD, two anti-spike, and four anti-nucleocapsid tests, either isolated or combined to improve their positive predictive values as predictors of the presence of high-titer nAbs, defined as those with titers ≥160. Except for combined and anti-IgA/M tests, all isolated surrogate tests showed excellent performance for nAb detection: sensitivity (98.3%-100%), specificity (85.7%-100%), PPV (98.9%-100%), NPV (81.3%-100%), and AUC (0.93-0.96), with a variable decrease in sensitivity and considerably lower specificity when using FDA authorization and concomitant nAb titers ≥160. All surrogates had AUCs that were statistically different from CPE-VNT if nAb≥160, including when using combined, orthogonal approaches. Surrogate tests (isolated or in combination) have an indirect good performance in detecting the presence of nAb, with lower sensitivity and specificity when high nAb titer samples are used, possibly accepting a considerable number of donors whose nAb titers are actually low, which should be evaluated by each laboratory responsible for CCP collection.

Wendel S ，Fachini R ，Fontão-Wendel RCL ，Mello R ，Velasquez CV ，Machado RRG ，Brito MA ，Amaral M ，Soares CP ，Achkar R ，Scuracchio P ，Miyaji SC ，Erdens MS ，Durigon EL ... -  《-》

Selecting COVID-19 convalescent plasma for neutralizing antibody potency using a high-capacity SARS-CoV-2 antibody assay.

Efficacy of COVID-19 convalescent plasma (CCP) is hypothesized to be associated with the concentration of neutralizing antibodies (nAb) to SARS-CoV-2. High capacity serologic assays detecting binding antibodies (bAb) have been developed; nAb assays are not adaptable to high-throughput testing. We sought to determine the effectiveness of using surrogate bAb signal-to-cutoff ratios (S/Co) in predicting nAb titers using a pseudovirus reporter viral particle neutralization (RVPN) assay. CCP donor serum collected by three US blood collectors was tested with a bAb assay (Ortho Clinical Diagnostics VITROS Anti-SARS-CoV-2 Total, CoV2T) and a nAb RVPN assay. Prediction effectiveness of various CoV2T S/Co criteria was evaluated for RVPN nAb NT50 titers using receiver operating characteristics. Seven hundred and fifty-three CCPs were tested with median CoV2T S/Co and NT50 of 71.2 of 527.5. Proportions of donors with NT50 over target nAb titers were 86% ≥1:80, 76% ≥1:160, and 62% ≥1:320. Increasing CoV2T S/Co criterion reduced the sensitivity to predict NT50 titers, while specificity to identify those below increased. As target NT50 titers increase, the CoV2T assay becomes less accurate as a predictor with a decline in positive predictive value and rise in negative predictive value. Selection of a clinically effective nAb titer will impact availability of CCP. Product release with CoV2T assay S/Co criterion must balance the risk of releasing products below target nAb titers with the cost of false negatives. A two-step testing scheme may be optimal, with nAb testing on CoV2T samples with S/Cos below criterion.

Goodhue Meyer E ，Simmons G ，Grebe E ，Gannett M ，Franz S ，Darst O ，Di Germanio C ，Stone M ，Contestable P ，Prichard A ，Reik R ，Vassallo R ，Young P ，Busch MP ，Williamson P ，Dumont LJ ... -  《-》

Feasibility of a pilot program for COVID-19 convalescent plasma collection in Wuhan, China.

A novel coronavirus has caused an international outbreak. Currently, there are no specific therapeutic agents for coronavirus infections. Convalescent plasma (CP) therapy is a potentially effective treatment option. Patients who had recovered from COVID-19 and had been discharged from the hospital for more than 2 weeks were recruited. COVID-19 convalescent plasma (CCP)-specific donor screening and selection were performed based on the following criteria: 1) aged 18-55 years; 2) eligible for blood donation; 3) diagnosed with COVID-19; 4) had two consecutive negative COVID-19 nasopharyngeal swab tests based on PCR (at least 24 hr apart) prior to hospital discharge; 5) had been discharged from the hospital for more than 2 weeks; and 6) had no COVID-19 symptoms prior to convalescent plasma donation. In addition, preference was given to CCP donors who had a fever lasting more than 3 days or a body temperature exceeding 38.5°C (101.3°F), and who donated 4 weeks after the onset of symptoms. CCP collection was performed using routine plasma collection procedures via plasmapheresis. In addition to routine donor testing, the CCP donors' plasma was also tested for SARS-CoV-2 nucleic acid and S-RBD-specific IgG antibody. Of the 81 potential CCP donors, 64 (79%) plasma products were collected. There were 18 female donors and 46 male donors. There were 34 first-time blood donors and 30 repeat donors. The average time between CCP collection and initial symptom onset was 49.1 days, and the average time between CCP collection and hospital discharge was 38.7 days. The average volume of CCP collected was 327.7 mL. All Alanine transaminase (ALT) testing results met blood donation requirements. HIV Ag/Ab, anti-HCV, anti-syphilis, and HBsAg were all negative; NAT for HIV, HBV, and HCV were also negative. In addition, all of the CCP donors' plasma units were negative for SARS-CoV-2 RNA. Of the total 64 CCP donors tested, only one had an S-RBD-specific IgG titer of 1:160, all others had a titer of ≥1:320. Based on a feasibility study of a pilot CCP program in Wuhan, China, we demonstrated the success and feasibility of CCP collection. In addition, all of the CCP units collected had a titer of ≥1:160 for S-RBD-specific IgG antibody, which met the CCP quality control requirements based on the Chinese national guidelines for CCP.

Li L ，Yang R ，Wang J ，Lv Q ，Ren M ，Zhao L ，Chen H ，Xu H ，Xie S ，Xie J ，Lin H ，Li W ，Fang P ，Gong L ，Wang L ，Wu Y ，Liu Z ... -  《-》