Marshall, Christi E.

BACKGROUND COVID-19 convalescent plasma (CCP) virus-specific antibody levels that translate into recipient posttransfusion antibody levels sufficient to prevent disease progression are not defined. METHODS This secondary analysis correlated donor and recipient antibody levels to hospitalization risk among unvaccinated, seronegative CCP recipients within the outpatient, double-blind, randomized clinical trial that compared CCP to control plasma. The majority of COVID-19 CCP arm hospitalizations (15/17, 88%) occurred in this unvaccinated, seronegative subgroup. A functional cutoff to delineate recipient high versus low posttransfusion antibody levels was established by 2 methods: (i) analyzing virus neutralization–equivalent anti–Spike receptor-binding domain immunoglobulin G (anti-S-RBD IgG) responses in donors or (ii) receiver operating characteristic (ROC) curve analysis. RESULTS SARS-CoV-2 anti–S-RBD IgG antibody was volume diluted 21.3-fold into posttransfusion seronegative recipients from matched donor units. Virus-specific antibody delivered was approximately 1.2 mg. The high-antibody recipients transfused early (symptom onset within 5 days) had no hospitalizations. A CCP-recipient analysis for antibody thresholds correlated to reduced hospitalizations found a statistical significant association between early transfusion and high antibodies versus all other CCP recipients (or control plasma), with antibody cutoffs established by both methods-donor-based virus neutralization cutoffs in posttransfusion recipients (0/85 [0%] versus 15/276 [5.6%]; P = 0.03) or ROC-based cutoff (0/94 [0%] versus 15/267 [5.4%]; P = 0.01). CONCLUSION In unvaccinated, seronegative CCP recipients, early transfusion of plasma units in the upper 30% of study donors’ antibody levels reduced outpatient hospitalizations. High antibody level plasma units, given early, should be reserved for therapeutic use. TRIAL REGISTRATION ClinicalTrials.gov NCT04373460. FUNDING Department of Defense (W911QY2090012); Defense Health Agency; Bloomberg Philanthropies; the State of Maryland; NIH (3R01AI152078-01S1, U24TR001609-S3, 1K23HL151826NIH); the Mental Wellness Foundation; the Moriah Fund; Octapharma; the Healthnetwork Foundation; the Shear Family Foundation; the NorthShore Research Institute; and the Rice Foundation.

AbstractBackgroundCOVID‐19 convalescent plasma (CCP) is an important therapeutic option for outpatients at high risk of hospitalization from SARS‐CoV‐2 infection. We assessed the safety of outpatient CCP transfusions administered during clinical trials.Study Design and MethodsWe analyzed data pertaining to transfusion‐related reactions from two randomized controlled trials in the U.S. that evaluated the efficacy of CCP versus control plasma in various ambulatory settings. Multivariable logistic regression was used to assess whether CCP was associated with transfusion reactions, after adjusting for potential confounders.ResultsThe combined study reported 79/1351 (5.9%) adverse events during the transfusion visit, with the majority 62/1351 (4.6%) characterized by mild, allergic‐type findings of urticaria, and/or pruritus consistent with minor allergic transfusion reactions; the other reported events were attributed to the patients' underlying disease, COVID‐19, or vasovagal in nature. We found no difference in the likelihood of allergic transfusion reactions between those receiving CCP versus control plasma (adjusted odds ratio [AOR], 0.75; 95% CI, 0.43–1.31). Risk of urticaria and/or pruritus increased with a pre‐existing diagnosis of asthma (AOR, 2.33; 95% CI, 1.16–4.67). We did not observe any CCP‐attributed antibody disease enhancement in participants with COVID‐19 or increased risk of infection. There were no life‐threatening severe transfusion reactions and no patients required hospitalization related to transfusion‐associated complications.DiscussionOutpatient plasma administration was safely performed for nearly 1400 participants. CCP is a safe therapeutic option for outpatients at risk of hospitalization from COVID‐19.

AbstractConvalescent plasma, collected from donors who have recovered from a pathogen of interest, has been used to treat infectious diseases, particularly in times of outbreak, when alternative therapies were unavailable. The COVID‐19 pandemic revived interest in the use of convalescent plasma. Large observational studies and clinical trials that were executed during the pandemic provided insight into how to use convalescent plasma, whereby high levels of antibodies against the pathogen of interest and administration early within the time course of the disease are critical for optimal therapeutic effect. Several studies have shown outpatient administration of COVID‐19 convalescent plasma (CCP) to be both safe and effective, preventing clinical progression in patients when administered within the first week of COVID‐19. The United States Food and Drug Administration expanded its emergency use authorization (EUA) to allow for the administration of CCP in an outpatient setting in December 2021, at least for immunocompromised patients or those on immunosuppressive therapy. Outpatient transfusion of CCP and infusion of monoclonal antibody therapies for a highly transmissible infectious disease introduces nuanced challenges related to infection prevention. Drawing on our experiences with the clinical and research use of CCP, we describe the logistical considerations and workflow spanning procurement of qualified products, infrastructure, staffing, transfusion, and associated management of adverse events. The purpose of this description is to facilitate the efforts of others intent on establishing outpatient transfusion programs for CCP and other antibody‐based therapies.

Background and ObjectivesABO blood group may affect risk of SARS‐CoV‐2 infection and/or severity of COVID‐19. We sought to determine whether IgG, IgA and neutralizing antibody (nAb) to SARS‐CoV‐2 vary by ABO blood group.Materials and MethodsAmong eligible convalescent plasma donors, ABO blood group was determined via agglutination of reagent A1 and B cells, IgA and IgG were quantified using the Euroimmun anti‐SARS‐CoV‐2 ELISA, and nAb titres were quantified using a microneutralization assay. Differences in titre distribution were examined by ABO blood group using non‐parametric Kruskal–Wallis tests. Adjusted prevalence ratios (aPR) of high nAb titre (≥1:160) were estimated by blood group using multivariable modified Poisson regression models that adjusted for age, sex, hospitalization status and time since SARS‐CoV‐2 diagnosis.ResultsOf the 202 potential donors, 65 (32%) were blood group A, 39 (19%) were group B, 13 (6%) were group AB, and 85 (42%) were group O. Distribution of nAb titres significantly differed by ABO blood group, whereas there were no significant differences in anti‐spike IgA or anti‐spike IgG titres by ABO blood group. There were significantly more individuals with high nAb titre (≥1:160) among those with blood group B, compared with group O (aPR = 1·9 [95%CI = 1·1–3·3], P = 0·029). Fewer individuals had a high nAb titre among those with blood group A, compared with group B (aPR = 0·6 [95%CI = 0·4‐1·0], P = 0·053).ConclusionEligible CCP donors with blood group B may have relatively higher neutralizing antibody titres. Additional studies evaluating ABO blood groups and antibody titres that incorporate COVID‐19 severity are needed.