Multi-institutional experience with COVID-19 convalescent plasma in children.

BACKGROUND AND OBJECTIVES: Convalescent COVID-19 plasma (CCP) was developed and used worldwide as a treatment option by supplying passive immunity. Adult studies suggest administering high-titer CCP early in the disease course of patients who are expected to be antibody-negative; however, pediatric experience is limited. We created a multi-institutional registry to characterize pediatric patients (<18 years) who received CCP and to assess the safety of this intervention. METHODS: A REDCap survey was distributed. The registry collected de-identified data including demographic information (age, gender, and underlying conditions), COVID-19 disease features and concurrent treatments, CCP transfusion and safety events, and therapy response. RESULTS: Ninety-five children received CCP: 90 inpatients and 5 outpatients, with a median age of 10.2 years (range 0-17.9). They were predominantly Latino/Hispanic and White. The most frequent underlying medical conditions were chronic respiratory disease, immunosuppression, obesity, and genetic syndromes. CCP was primarily given as a treatment (95%) rather than prophylaxis (5%). Median total plasma dose administered and transfusion rates were 5.0 ml/kg and 2.6 ml/kg/h, respectively. The transfusions were well-tolerated, with 3 in 115 transfusions reporting mild reactions. No serious adverse events were reported. Severity scores decreased significantly 7 days after CCP transfusion or at discharge. Eighty-five patients (94.4%) survived to hospital discharge. All five outpatients survived to 60 days. CONCLUSIONS: CCP was found to be safe and well-tolerated in children. CCP was frequently given concurrently with other COVID-19-directed treatments with improvement in clinical severity scores ≥7 days after CCP, but efficacy could not be evaluated in this study.

A Multicenter, Prospective, Observational, Cohort-Controlled Study of Clinical Outcomes Following Coronavirus Disease 2019 (COVID-19) Convalescent Plasma Therapy in Hospitalized Patients With COVID-19.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused high inpatient mortality and morbidity throughout the world. COVID-19 convalescent plasma (CCP) has been utilized as a potential therapy for patients hospitalized with coronavirus disease 2019 (COVID-19) pneumonia. This study evaluated the outcomes of hospitalized patients with COVID-19 treated with CCP in a prospective, observational, multicenter trial. METHODS: From April through August 2020, hospitalized patients with COVID-19 at 16 participating hospitals in Colorado were enrolled and treated with CCP and compared with hospitalized patients with COVID-19 who were not treated with convalescent plasma. Plasma antibody levels were determined following the trial, given that antibody tests were not approved at the initiation of the trial. CCP-treated and untreated hospitalized patients with COVID-19 were matched using propensity scores followed by analysis for length of hospitalization and inpatient mortality. RESULTS: A total of 542 hospitalized patients with COVID-19 were enrolled at 16 hospitals across the region. A total of 468 hospitalized patients with COVID-19 were entered into propensity score matching with 188 patients matched for analysis in the CCP-treatment and control arms. Fine-Gray models revealed increased length of hospital stay in CCP-treated patients and no change in inpatient mortality compared with controls. In subgroup analysis of CCP-treated patients within 7 days of admission, there was no difference in length of hospitalization and inpatient mortality. CONCLUSIONS: These data show that treatment of hospitalized patients with COVID-19 treated with CCP did not significantly improve patient hospitalization length of stay or inpatient mortality.

Evaluation of a multiplexed coronavirus antigen array for detection of SARS-CoV-2 specific IgG in COVID-19 convalescent plasma.

Mitigation of the COVID-19 pandemic requires an understanding of the antibody response to SARS-CoV-2. However, throughout the development of SARS-CoV-2 IgG antibody assays during the past year, cross-reactivity to other coronaviruses remained a question. To address these issues, we evaluated IgG in COVID-19 convalescent plasma samples for reactivity against three SARS-CoV-2 antigens including full-length spike, receptor binding domain, and the proximal extracellular fusion domain, and spike antigens from other coronaviruses (SARS-CoV, MERS-CoV, hCoV-HKU1, hCoV-OC43, hCoV-229E and hCoV-NL63) using the VaxArray Coronavirus SeroAssay which is a multiplexed antigen assay developed by InDevR Inc. These results were compared to two commercial SARS-CoV-2 IgG ELISAs targeting either the SARS-CoV-2 nucleocapsid or spike antigens and a live virus focus reduction neutralizing antibody test (FRNT). The VaxArray platform showed high specificity for detection of SARS-CoV-2 IgG, evident from lack of reactivity to SARS-CoV-2 antigens despite significant reactivity to endemic coronavirus antigens in pre-pandemic samples. SARS-CoV-2 IgG positive samples reacted weakly to SARS-CoV spike but not to MERS-CoV. While the VaxArray platform had overall comparable results to the spike and nucleocapsid IgG ELISAs, results were more similar to the spike antigen ELISA and the platform displayed a higher sensitivity and specificity than both ELISAs. Samples with FRNT titers below 1/23 reported negative on VaxArray, while positive samples on VaxArray had significantly higher neutralizing antibody titers. These results suggest that the VaxArray Coronavirus SeroAssay performs with high sensitivity and specificity for the detection of SARS-CoV-2 IgG, and positive results on the platform indicate SARS-CoV-2 neutralizing activity.

Development and Validation of a Multiplex Microsphere Immunoassay Using Dried Blood Spots for SARS-CoV-2 Seroprevalence: Application in First Responders in Colorado, USA.

Serological testing of large representative populations for antibodies to SARS-CoV-2 is needed to estimate seroprevalence, transmission dynamics, and the duration of antibody responses from natural infection and vaccination. In this study, a high-throughput SARS-CoV-2 multiplex microsphere immunoassay (MMIA) was developed for the receptor binding domain (RBD) and nucleocapsid (N) that was more sensitive than enzyme-linked immunosorbent assay (ELISA) (98% versus 87%). The MMIA was then applied and validated in 264 first responders in Colorado using serum and dried blood spot (DBS) eluates, compared to ELISA, and evaluated for neutralizing antibodies. Four percent (11/264) of first responders were seropositive in July to August 2020. Serum and DBS were highly correlated for anti-RBD and anti-N antibodies (R = 0.83, P < 0.0001 and R = 0.87, P < 0.0001, respectively) by MMIA. The MMIA accurately predicted SARS-CoV-2 neutralizing antibodies using DBS (R = 0.76, P = 0.037). On repeat antibody testing 3 months later, anti-RBD IgG decreased less rapidly than anti-N IgG measured by MMIA, with a median change in geometric median fluorescence intensity of 62% versus 79% (P < 0.01) for anti-RBD and anti-N IgG, respectively. This novel MMIA using DBS could be scalable for rapid and affordable SARS-CoV-2 serosurveillance in the United States and globally.

A New SARS-CoV-2 Dual-Purpose Serology Test: Highly Accurate Infection Tracing and Neutralizing Antibody Response Detection.

Many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology tests have proven to be less accurate than expected and do not assess antibody function as neutralizing, correlating with protection from reinfection. A new assay technology measuring the interaction of the purified SARS-CoV-2 spike protein receptor binding domain (RBD) with the extracellular domain of the human angiotensin-converting enzyme 2 (hACE2) receptor detects these important antibodies. The cPass surrogate virus neutralization test (sVNT), compared directly with eight SARS-CoV-2 IgG serology and two live-cell neutralization tests, gives similar or improved accuracy for qualitative delineation between positive and negative individuals in a fast, scalable, and high-throughput assay. The combined data support the cPass sVNT as a tool for highly accurate SARS-CoV-2 immunity surveillance of infected/recovered and/or vaccinated individuals as well as drug and convalescent-phase donor screening. The data also preview a novel application for the cPass sVNT in calibrating the stringency of live-cell neutralization tests and its use in longitudinal testing of recovered and/or vaccinated patients.

Presence and short-term persistence of SARS-CoV-2 neutralizing antibodies in COVID-19 convalescent plasma donors.

BACKGROUND: In March 2020, the Food and Drug Administration (FDA) approved use of COVID-19 convalescent plasma (CCP) as an investigational new drug for treatment of COVID-19. Since then, collection of CCP from COVID-19-recovered patients has been implemented in donor centers nationwide. Children's Hospital Colorado rapidly put into practice a CCP collection protocol, necessitating development and implementation of assays to evaluate SARS-CoV-2 antibodies in CCP units. STUDY DESIGN AND METHODS: We evaluated 87 units of CCP collected from 36 donors over two to four sequential donations using both antigen-binding assays for SARS-CoV-2 nucleoprotein and spike antigens and a live virus focus reduction neutralization test (FRNT50 ). RESULTS: Our data show that the majority of donors (83%) had a FRNT50 titer of at least 80, and 61% had a titer of at least 160, which met the FDA's criteria for acceptable CCP units. Additionally, our data indicate that analysis of antibodies to a single SARS-CoV-2 antigen is likely to miss a percentage of seroconverters; however, these individuals tend to have neutralizing antibody titers of less than 80. There was considerable variability in the short-term, sustained antibody response, measured by neutralizing antibody titers, among our donor population. CONCLUSION: The correlation of neutralizing activity and antigen-binding assays is necessary to qualify CCP for therapeutic use. Since SARS-CoV-2 antibody levels decline in a percentage of donors, and such a decline is not detectable by current qualitative assays implemented in many laboratories, robust, quantitative assays are necessary to evaluate CCP units best suited for therapeutic infusion in COVID-19 patients.

Analysis of COVID-19 convalescent plasma for SARS-CoV-2 IgG using two commercial immunoassays.

Coronavirus Disease 2019 (COVID-19) convalescent plasma (CCP) was approved by the FDA for use in severe cases of COVID-19 under an emergency Investigational New Drug (IND) protocol. Eligibility criteria for CCP donors includes documentation of evidence of COVID-19 either by viral RNA detection at the time of illness or positive SARS-CoV-2 IgG after recovery if diagnostic testing for COVID-19 was not performed at the time of illness. In addition to analysis of CCP, analysis of SARS-CoV-2 IgG provides information for possible past exposure and may support diagnosis when SARS-CoV-2 PCR is negative and clinical suspicion for COVID-19 is high. Furthermore, assays with high sensitivity and specificity for SARS-CoV-2 IgG are critical for understanding community exposure rates to SARS-CoV-2. Currently, there are several assays that test for antibodies to SARS-CoV-2 using a variety of methods, including point-of-care lateral flow-based devices, high throughput immunoassay analyzers, and manual methods such as ELISA. These assays target a number of SARS-CoV-2 antigens, including the nucleocapsid protein (N), full length spike protein (S), S1 subunit, or receptor binding domain (RBD) of the S protein. Given the heterogeneity among methods for, and antigenic targets used in SARS-CoV-2 antibody assays, it is necessary for careful evaluation of these assays prior to implementation for clinical use. We compared two assays that had received the CE mark of regulatory approval and that used either the N antigen or S1-RBD antigen as the target for analysis of a large set of CCP samples. Our data indicates that sensitivity and specificity vary between these assays and that more than one antigenic target may be required to improve the sensitivity and specificity of IgG detection to SARS-CoV-2.