Updated Guidance Regarding The Risk ofAllergic Reactions to COVID-19 Vaccines and Recommended Evaluation and Management: A GRADE Assessment, and International Consensus Approach.

This guidance updates 2021 GRADE recomendations regarding immediate allergic reactions following COVID-19 vaccines and addresses re-vaccinating individuals with 1st dose allergic reactions and allergy testing to determine re-vaccination outcomes. Recent meta-analyses assessed the incidence of severe allergic reactions to initial COVID-19 vaccination, risk of mRNA-COVID-19 re-vaccination after an initial reaction, and diagnostic accuracy of COVID-19 vaccine and vaccine excipient testing in predicting reactions. GRADE methods informed rating the certainty of evidence and strength of recommenations. A modified Delphi panel consisting of experts in allergy, anaphylaxis, vaccinology, infectious diseases, emergency medicine, and primary care from Australia, Canada, Europe, Japan, South Africa, the UK, and the US formed the recommendations. We recommend vaccination for persons without COVID-19 vaccine excipient allergy, and re-vaccination after a prior immediate allergic reaction. We suggest against >15-minute post-vaccination observation. We recommend against mRNA vaccine or excipient skin testing to predict outcomes. We suggest re-vaccination of persons with an immediate allergic reaction to the mRNA vaccine or excipients be performed by a person with vaccine allergy expertise, in a properly equipped setting. We suggest against pre-medication, split-dosing, or special precautions because of a comorbid allergic history.

Lessons learned from the CONCOR-1 trial.

Faced with an evolving pandemic and a lack of clarity of the role of convalescent plasma for patients with COVID-19, the CONCOR-1 trial was launched. In 14 months the trial was designed, launched, completed, and submitted for publication. In total, 72 sites in three countries served by four blood suppliers randomised 940 patients. Many enablers facilitated the trial including: three study principal investigators to distribute the trial workload, diverse steering committee members, an international data safety monitoring committee, multiple statisticians and methodologists, virtual meeting platforms, REDCap data platform, pausing of non-COVID-19 trials, rapid approval pathways for institutional review boards and regulators, centralised institutional review boards in many locations, restriction of use of convalescent plasma to trial participants and the incredible dedication by research personnel. In future pandemics, we need to be prepared for rapid launch of trials. The protocols, consent forms, data collection tools, and procedures need to be in draft form ready for use at all times. We were well-prepared for blood shortages but should have anticipated the need to conduct trials with convalescent plasma. In this short article, we detail our lessons learned to inform researchers faced with the next pandemic pathogen.

Vaccine confidence among those living with allergy during the COVID pandemic (ACCORD): A scoping review.

Background: Reports of allergic reactions to coronavirus disease 2019 (COVID-19) vaccines, coupled with an "infodemic" of misinformation, carry the potential to undermine confidence in the COVID-19 vaccines. However, no attempts have been made to comprehensively synthesize the literature on how allergic disease and fear of allergic reactions to the vaccines contribute to hesitancy. Objectives: Our aim was to review the academic and gray literature on COVID-19 vaccine hesitancy and allergic reactions. Methods: We searched 4 databases (CINAHL, PsycINFO, MEDLINE, and Embase) using a search strategy developed by content and methodologic experts. No restrictions were applied regarding COVID-19 vaccine type, country of study, or patient age. Eligible articles were restricted to 10 languages. Results: Of the 1385 unique records retrieved from our search, 60 articles (4.3%) were included. Allergic reactions to the COVID-19 vaccine were rare but slightly more common in individuals with a history of allergic disease. A fifth of the studies (13 of 60 [22%]) discussed vaccine hesitancy due to possibility of an allergic reaction. Additionally, the present review identified research on details of vaccine-related anaphylaxis (eg, a mean and median [excluding clinical trial data] of 12.4 and 5 cases per million doses, respectively) and allergic reactions (eg, a mean and median [excluding clinical trial data] of 489 and 528 cases per million doses, respectively). Conclusion: COVID-19 vaccine acceptance among individuals living with allergy and among those with no history of allergic disease may be affected by fear of an allergic reaction. Despite the low incidence of allergic reactions to the COVID-19 vaccine, fear of such reactions is one of the most commonly cited concerns reported in the literature.

The Fc-effector function of COVID-19 convalescent plasma contributes to SARS-CoV-2 treatment efficacy in mice.

COVID-19 convalescent plasmas (CCPs) are chosen for plasma therapy based on neutralizing titers and anti-Spike immunoglobulin levels. However, CCP characteristics that promote SARS-CoV-2 control are complex and incompletely defined. Using an in vivo imaging approach, we demonstrate that CCPs with low neutralizing (ID50 ≤ 1:250), but moderate to high Fc-effector activity, in contrast to those with poor Fc function, delay mortality and/or improve survival of SARS-CoV-2-challenged K18-hACE2 mice. The impact of innate immune cells on CCP efficacy depended on their residual neutralizing activity. Fractionation of a selected CCP revealed that IgG and Ig(M + A) were required during therapy, but the IgG fraction alone sufficed during prophylaxis. Finally, despite reduced neutralization, ancestral SARS-CoV-2-elicited CCPs significantly delayed Delta and Beta-induced mortality suggesting that Fc-effector functions contribute to immunity against VOCs. Thus, Fc activity of CCPs provide a second line of defense when neutralization is compromised and can serve as an important criterion for CCP selection.

Multisystem inflammatory syndrome in adults: Comparison with other inflammatory conditions during the Covid-19 pandemic.

BACKGROUND: Multisystem inflammatory syndrome in adults (MIS-A) is an increasingly recognized complication of Covid-19. We assessed risk factors, clinical characteristics, and outcomes of patients with MIS-A compared with other inflammatory conditions. METHODS: We analyzed a cohort of patients ≥21 years hospitalized with MIS-A in Quebec, Canada between February 2020 and March 2021. We included comparison groups that share symptomatology or pathophysiology with MIS-A, including Kawasaki disease, toxic shock syndrome, and other Covid-19 complications. We examined characteristics of men and women at admission, and identified preexisting factors associated with MIS-A through odds ratios (OR) and 95% confidence intervals (CI) from adjusted logistic regression models. RESULTS: Among 22,251 patients in this study, 52 had MIS-A, 90 Kawasaki disease, 500 toxic shock syndrome, and 21,609 other Covid-19 complications. MIS-A was associated with an elevated risk of respiratory failure compared with Kawasaki disease (OR 7.22, 95% CI 1.26-41.24), toxic shock syndrome (OR 4.41, 95% CI 1.73-11.23), and other Covid-19 complications (OR 3.03, 95% CI 1.67-5.50). Patients with MIS-A had a greater risk of cardiac involvement, renal failure, and mortality. The data pointed towards sex-specific differences in presentation, with more respiratory involvement in women and cardiac involvement in men compared with patients that had other Covid-19 complications. Except for allergic disorders and cancer, prior medical risk factors were not associated with a greater likelihood of MIS-A. CONCLUSIONS: Patients with MIS-A have an elevated risk of mortality compared with other inflammatory conditions, with women having a predominance of respiratory complications and men cardiovascular complications.

Blood Endothelial-Cell Extracellular Vesicles as Potential Biomarkers for the Selection of Plasma in COVID-19 Convalescent Plasma Therapy.

Despite the advancement of vaccination and therapies currently available, deaths due to the coronavirus disease 2019 (COVID-19) are still heavily documented. Severely infected individuals experience a generalized inflammatory storm, caused by massive secretion of pro-inflammatory cytokines that can lead to endothelial dysfunction, cardiovascular disease, multi-organ failure, and even death. COVID-19 convalescent plasma (CCP) therapy, selected primarily based on anti-SARS-CoV-2 antibody levels, has not been as convincing as expected in the fight against COVID-19. Given the consequences of a dysfunctional endothelium on the progression of the disease, we propose that the selection of plasma for CCP therapy should be based on more specific parameters that take into consideration the effect on vascular inflammation. Thus, in the present study, we have characterized a subset of CCP that have been used for CCP therapy and measured their anti- or pro-inflammatory effect on human coronary artery endothelial cells (HCAECs). Our data revealed that the longer the time lapse between the onset of symptoms and the plasma donation, the more mitochondrial dysfunction can be evidenced. The concentration of blood endothelial cell extracellular vesicles (BEC-EVs) was increased in the plasma of young individuals with mild symptoms. This type of selected convalescent plasma promoted the activation of the blood vascular endothelium, as reflected by the overexpression of ICAM1 and NFκB1 and the downregulation of VE-Cadherin. We propose this mechanism is a warning signal sent by the injured endothelium to trigger self-defense of peripheral blood vessels against excessive inflammation. Therefore, these results are in line with our previous data. They suggest that a more specific selection of COVID-19 convalescent plasma should be based on the time of donation following the onset of the clinical symptoms of the donor, the severity of the symptoms, and the age of the donor. These characteristics are relatively easy to identify in any hospital and would reflect the concentration of plasma BEC-EVs and be optimal in CCP therapy.

vACcine COnfidence amongst those living with alleRgy during the COVID pandemic (ACCORD): a scoping review protocol.

BACKGROUND: Reports of allergic reactions to the COVID-19 vaccines have been documented, which may also contribute to hesitancy. Despite the low likelihood that the COVID-19 vaccine will trigger an allergic reaction, we and others have reported that families with allergy remain vaccine hesitant due to concerns of COVID-19-vaccine-triggered anaphylaxis. OBJECTIVE: To present our scoping review protocol, that will inform a forthcoming living scoping review in which we will investigate the peer-reviewed and grey literature on COVID-19 vaccine hesitancy and allergic disease and/or allergic reactions following a COVID-19 vaccine. METHODS: Informed by Arksey and O'Malley framework for methodological review, we have developed a search strategy with content and methodological experts, and which has undergone Peer Review of Electronic Search Strategies review. A search of four scientific databases, as well as gray literature, will be performed without restriction to articles by type of COVID-19 vaccine, or country of study, and will include publications in the ten languages our team can handle. Bi-monthly search alerts based on the search strategy will be generated. RESULTS: The first search will result in a stand alone peer reviewed scoping review. Bi-monthly updates will be posted on a pre-print server. Depending on the volume of literature, these updates will be synthesized and submitted for peer-review at 6 and/or 12 months. CONCLUSION: COVID-19 vaccine hesitancy amongst individuals with allergy persists, despite very low risk of serious adverse reactions. Our living scoping review, which includes multiple forms of knowledge translation, will be a rigorous way to address hesitancy.

Changes in food-related costs during the COVID-19 pandemic among families managing food allergy.

Background: The COVID-19 pandemic has affected the supply, cost, and demand for certain foods, but it is not clear how these changes have affected food-allergic households. Objective: To describe the changes in food-related costs that have followed COVID-19, as reported by higher- and lower-income households with a food-allergic member. Methods: Between May 1-June 30, 2020, Canadian households, with at least one food-allergic member, completed an online survey on food shopping and preparation habits before and during the COVID-19 pandemic. The sample was divided into binary groups, either higher or lower than the sample median income. Data were analyzed using descriptive statistics and multiple regression. Results: The sample was comprised of 102 participants (i.e., 51/ income group). The three most common food allergies amongst both groups were peanuts, tree nuts and milk. Since the start of the pandemic, both groups reported greater monthly direct grocery costs, although costs amongst the higher-income group were twice as high as the lower-income group ($212.86 vs. $98.89, respectively). Indirect food preparation costs were similarly elevated. Higher-income households with food procurement difficulties reported increased indirect shopping costs following the outbreak of COVID-19, whereas those without such difficulties reported decreased costs. Lower-income households with allergies to milk, wheat, or eggs (i.e., staple allergy) experienced a larger change in indirect food preparation costs following the outbreak of COVID-19 relative to those with other food allergies ($244.58 vs. -$20.28, respectively; p = 0.03). Conclusion: Both higher and lower income households with food allergy reported greater direct food costs and indirect food preparation costs following the COVID-19. Households with staple allergy and those with difficulties finding their typical food items were particularly affected.

Use of Early Donated COVID-19 Convalescent Plasma Is Optimal to Preserve the Integrity of Lymphatic Endothelial Cells.

Convalescent plasma therapy (CPT) has gained significant attention since the onset of the coronavirus disease 2019 (COVID-19) pandemic. However, clinical trials designed to study the efficacy of CPT based on antibody concentrations were inconclusive. Lymphatic transport is at the interplay between the immune response and the resolution of inflammation from peripheral tissues, including the artery wall. As vascular complications are a key pathogenic mechanism in COVID-19, leading to inflammation and multiple organ failure, we believe that sustaining lymphatic vessel function should be considered to define optimal CPT. We herein sought to determine what specific COVID-19 convalescent plasma (CCP) characteristics should be considered to limit inflammation-driven lymphatic endothelial cells (LEC) dysfunction. CCP donated 16 to 100 days after the last day of symptoms was characterized and incubated on inflammation-elicited adult human dermal LEC (aHDLEC). Plasma analysis revealed that late donation correlates with higher concentration of circulating pro-inflammatory cytokines. Conversely, extracellular vesicles (EVs) derived from LEC are more abundant in early donated plasma (r = -0.413, p = 0.004). Thus, secretion of LEC-EVs by an impaired endothelium could be an alarm signal that instigate the self-defense of peripheral lymphatic vessels against an excessive inflammation. Indeed, in vitro experiments suggest that CCP obtained rapidly following the onset of symptoms does not damage the aHDLEC junctions as much as late-donated plasma. We identified a particular signature of CCP that would counteract the effects of an excessive inflammation on the lymphatic endothelium. Accordingly, an easy and efficient selection of convalescent plasma based on time of donation would be essential to promote the preservation of the lymphatic and immune system of infected patients.

Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial.

IMPORTANCE: The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive. OBJECTIVE: To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19. DESIGN, SETTING, AND PARTICIPANTS: The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021. INTERVENTIONS: The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916). MAIN OUTCOMES AND MEASURES: The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority >99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility >95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events. RESULTS: Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (OR <1.2) was 99.4% for the convalescent plasma group compared with the no convalescent plasma group. The treatment effects were consistent across the primary outcome and the 11 secondary outcomes. Serious adverse events were reported in 3.0% (32/1075) of participants in the convalescent plasma group and in 1.3% (12/905) of participants in the no convalescent plasma group. CONCLUSIONS AND RELEVANCE: Among critically ill adults with confirmed COVID-19, treatment with 2 units of high-titer, ABO-compatible convalescent plasma had a low likelihood of providing improvement in the number of organ support-free days. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02735707.

Convalescent plasma for hospitalized patients with COVID-19: an open-label, randomized controlled trial.

The efficacy of convalescent plasma for coronavirus disease 2019 (COVID-19) is unclear. Although most randomized controlled trials have shown negative results, uncontrolled studies have suggested that the antibody content could influence patient outcomes. We conducted an open-label, randomized controlled trial of convalescent plasma for adults with COVID-19 receiving oxygen within 12 d of respiratory symptom onset ( NCT04348656 ). Patients were allocated 2:1 to 500 ml of convalescent plasma or standard of care. The composite primary outcome was intubation or death by 30 d. Exploratory analyses of the effect of convalescent plasma antibodies on the primary outcome was assessed by logistic regression. The trial was terminated at 78% of planned enrollment after meeting stopping criteria for futility. In total, 940 patients were randomized, and 921 patients were included in the intention-to-treat analysis. Intubation or death occurred in 199/614 (32.4%) patients in the convalescent plasma arm and 86/307 (28.0%) patients in the standard of care arm-relative risk (RR) = 1.16 (95% confidence interval (CI) 0.94-1.43, P = 0.18). Patients in the convalescent plasma arm had more serious adverse events (33.4% versus 26.4%; RR = 1.27, 95% CI 1.02-1.57, P = 0.034). The antibody content significantly modulated the therapeutic effect of convalescent plasma. In multivariate analysis, each standardized log increase in neutralization or antibody-dependent cellular cytotoxicity independently reduced the potential harmful effect of plasma (odds ratio (OR) = 0.74, 95% CI 0.57-0.95 and OR = 0.66, 95% CI 0.50-0.87, respectively), whereas IgG against the full transmembrane spike protein increased it (OR = 1.53, 95% CI 1.14-2.05). Convalescent plasma did not reduce the risk of intubation or death at 30 d in hospitalized patients with COVID-19. Transfusion of convalescent plasma with unfavorable antibody profiles could be associated with worse clinical outcomes compared to standard care.

Evaluation of Adverse Reactions to Vaccines.

The development and widespread use of vaccination over the past centuries has been the single most impactful intervention in public health, by effectively preventing morbidity and mortality from infectious diseases. Vaccination is generally well tolerated in the vast majority of the population, and the benefits of vaccination largely outweigh the risk of severe adverse events in the majority of patients. Vaccine hesitancy can be a significant concern and lead to infectious disease outbreaks. All health care providers play an important role in maintaining public confidence in vaccines because their attitude and knowledge is often critical in facilitating acceptance of a vaccine. The purpose of this review is to first, provide an understanding of the basic concepts that are relevant to vaccine pharmacovigilance, and secondly, to provide an overview and discuss management of both immune and nonimmune adverse events after vaccination.

Longitudinal analysis of humoral immunity against SARS-CoV-2 Spike in convalescent individuals up to 8 months post-symptom onset.

With the recent approval of highly effective coronavirus disease 2019 (COVID-19) vaccines, functional and lasting immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently under investigation as antibody levels in plasma were shown to decline during convalescence. Since the absence of antibodies does not equate to absence of immune memory, we evaluate the presence of SARS-CoV-2-specific memory B cells in convalescent individuals. Here, we report a longitudinal assessment of humoral immune responses on 32 donors up to 8 months post-symptom onset. Our observations indicate that anti-Spike and anti-receptor binding domain (RBD) immunoglobulin M (IgM) in plasma decay rapidly, whereas the reduction of IgG is less prominent. Neutralizing activity also declines rapidly when compared to Fc-effector functions. Concomitantly, the frequencies of RBD-specific IgM+ B cells wane significantly when compared to RBD-specific IgG+ B cells, which remain stable. Our results add to the current understanding of immune memory following SARS-CoV-2 infection, which is critical for secondary infection prevention and vaccine efficacy.

Convalescent plasma for adults with acute COVID-19 respiratory illness (CONCOR-1): study protocol for an international, multicentre, randomized, open-label trial.

BACKGROUND: Convalescent plasma has been used for numerous viral diseases including influenza, severe acute respiratory syndrome, Middle East respiratory syndrome and Ebola virus; however, evidence to support its use is weak. SARS-CoV-2 is a novel coronavirus responsible for the 2019 global pandemic of COVID-19 community acquired pneumonia. We have undertaken a randomized controlled trial to assess the efficacy and safety of COVID-19 convalescent plasma (CCP) in patients with SARS-CoV-2 infection. METHODS: CONCOR-1 is an open-label, multicentre, randomized trial. Inclusion criteria include the following: patients > 16 years, admitted to hospital with COVID-19 infection, receiving supplemental oxygen for respiratory complications of COVID-19, and availability of blood group compatible CCP. Exclusion criteria are : onset of respiratory symptoms more than 12 days prior to randomization, intubated or imminent plan for intubation, and previous severe reactions to plasma. Consenting patients are randomized 2:1 to receive either approximately 500 mL of CCP or standard of care. CCP is collected from donors who have recovered from COVID-19 and who have detectable anti-SARS-CoV-2 antibodies quantified serologically. The primary outcome is intubation or death at day 30. Secondary outcomes include ventilator-free days, length of stay in intensive care or hospital, transfusion reactions, serious adverse events, and reduction in SARS-CoV-2 viral load. Exploratory analyses include patients who received CCP containing high titre antibodies. A sample size of 1200 patients gives 80% power to detect a 25% relative risk reduction assuming a 30% baseline risk of intubation or death at 30 days (two-sided test; α = 0.05). An interim analysis and sample size re-estimation will be done by an unblinded independent biostatistician after primary outcome data are available for 50% of the target recruitment (n = 600). DISCUSSION: This trial will determine whether CCP will reduce intubation or death non-intubated adults with COVID-19. The trial will also provide information on the role of and thresholds for SARS-CoV-2 antibody titres and neutralization assays for donor qualification. TRIAL REGISTRATION: Clinicaltrials.gov NCT04348656 . Registered on 16 April 2020.

Efficacité et innocuité du plasma de convalescent en cas de forme grave de COVID-19, extrapolée de données relatives à d'autres formes graves d'infections respiratoires virales : revue systématique et méta-analyse.

CONTEXTE: On ne connaît pas encore avec certitude l'innocuité et l'efficacité du plasma de convalescent comme traitement de la forme grave de la maladie à coronavirus 2019 (COVID-2019). Afin d'appuyer la conception de lignes directrices sur la prise en charge de la COVID-19, nous avons effectué une revue systématique et une méta-analyse sur l'utilisation du plasma de convalescent pour le traitement de cette maladie et d'autres formes graves d'infections respiratoires virales. MÉTHODES: En mars 2020, nous avons effectué des recherches dans des bases de données biomédicales internationales et chinoises, des registres d'essais cliniques et des sources prépubliées afin de recenser des essais randomisés et contrôlés (ERC) et des études non randomisées comparant les issues de patients ayant reçu du plasma de convalescent à celles de patients n'en ayant pas reçu. Ont été inclus les patients ayant une infection aiguë attribuable à un coronavirus, au virus de l'influenza ou au virus Ebola. Nous avons également réalisé une méta-analyse à l'aide d'un modèle à effets aléatoires et évalué la qualité des données probantes au moyen de l'approche GRADE (Grading of Recommendations Assessment, Development, and Evaluation). RÉSULTATS: Sur les 1099 études uniques initialement repérées, 6 étaient admissibles, et aucune d'entre elles ne portait sur des patients atteints de la COVID-19. Une étude non randomisée (n = 40) sur l'administration de plasma de convalescent à des patients atteints du coronavirus du syndrome respiratoire aigu sévère (SRAS-CoV) a fourni des données peu concluantes sur le taux de mortalité (risque relatif [RR] 0,10; intervalle de confiance [IC] de 95 % 0,01 à 1,70). Des estimations regroupées provenant de 4 ERC sur l'influenza (n = 572) n'ont pas montré d'effet manifeste sur le taux de mortalité (4 ERC; RR 0,94; IC de 95 % 0,49 à 1,81), le rétablissement complet (2 ERC; rapports de cotes [RC] 1,04; IC de 95 % 0,69 à 1,64) et la durée d'hospitalisation (3 ERC; différence moyenne [DM] −1,62; IC de 95 % −3,82 à 0,58 jours). La qualité des données était très faible pour tous les paramètres relatifs à l'efficacité. Dans les ERC sur l'influenza, aucun ou peu d'événements indésirables graves ont été associés au plasma de convalescent (RR 0,85; IC de 95 % 0,56 à 1,29; données de faible qualité). INTERPRÉTATION: Les études portant sur des formes graves d'infections respiratoires virales autres que la COVID-19 ont fourni des données indirectes de très faible qualité semblant indiquer que le plasma de convalescent n'offre aucun bénéfice ou offre des bénéfices minimes pour le traitement de la COVID-19, de même que des données de faible qualité montrant qu'il n'entraîne pas d'événements indésirables graves.

Decline of Humoral Responses against SARS-CoV-2 Spike in Convalescent Individuals.

In the absence of effective vaccines and with limited therapeutic options, convalescent plasma is being collected across the globe for potential transfusion to coronavirus disease 2019 (COVID-19) patients. The therapy has been deemed safe, and several clinical trials assessing its efficacy are ongoing. While it remains to be formally proven, the presence of neutralizing antibodies is thought to play a positive role in the efficacy of this treatment. Indeed, neutralizing titers of ≥1:160 have been recommended in some convalescent plasma trials for inclusion. Here, we performed repeated analyses at 1-month intervals on 31 convalescent individuals to evaluate how the humoral responses against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike glycoprotein, including neutralization, evolve over time. We observed that the levels of receptor-binding-domain (RBD)-specific IgG and IgA slightly decreased between 6 and 10 weeks after the onset of symptoms but that RBD-specific IgM levels decreased much more abruptly. Similarly, we observed a significant decrease in the capacity of convalescent plasma to neutralize pseudoparticles bearing wild-type SARS-CoV-2 S or its D614G variant. If neutralization activity proves to be an important factor in the clinical efficacy of convalescent plasma transfer, our results suggest that plasma from convalescent donors should be recovered rapidly after resolution of symptoms.IMPORTANCE While waiting for an efficient vaccine to protect against SARS-CoV-2 infection, alternative approaches to treat or prevent acute COVID-19 are urgently needed. Transfusion of convalescent plasma to treat COVID-19 patients is currently being explored; neutralizing activity in convalescent plasma is thought to play a central role in the efficacy of this treatment. Here, we observed that plasma neutralization activity decreased a few weeks after the onset of the symptoms. If neutralizing activity is required for the efficacy of convalescent plasma transfer, our results suggest that convalescent plasma should be recovered rapidly after the donor recovers from active infection.

Efficacy and safety of convalescent plasma for severe COVID-19 based on evidence in other severe respiratory viral infections: a systematic review and meta-analysis.

BACKGROUND: The safety and efficacy of convalescent plasma in severe coronavirus disease 2019 (COVID-19) remain uncertain. To support a guideline on COVID-19 management, we conducted a systematic review and meta-analysis of convalescent plasma in COVID-19 and other severe respiratory viral infections. METHODS: In March 2020, we searched international and Chinese biomedical literature databases, clinical trial registries and prepublication sources for randomized controlled trials (RCTs) and nonrandomized studies comparing patients receiving and not receiving convalescent plasma. We included patients with acute coronavirus, influenza and Ebola virus infections. We conducted a meta-analysis using random-effects models and assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. RESULTS: Of 1099 unique records, 6 studies were eligible, and none of these included patients with COVID-19. One nonrandomized study (n = 40) on convalescent plasma in severe acute respiratory syndrome coronavirus (SARS-CoV) provided uninformative results regarding mortality (relative risk [RR] 0.10, 95% confidence interval [CI] CI 0.01 to 1.70). Pooled estimates from 4 RCTs on influenza (n = 572) showed no convincing effects on deaths (4 RCTs, RR 0.94, 95% CI 0.49 to 1.81), complete recovery (2 RCTs, odds ratio 1.04, 95% CI 0.69 to 1.64) or length of stay (3 RCTs, mean difference -1.62, 95% CI -3.82 to 0.58, d). The quality of evidence was very low for all efficacy outcomes. Convalescent plasma caused few or no serious adverse events in influenza RCTs (RR 0.85, 95% CI 0.56 to 1.29, low-quality evidence). INTERPRETATION: Studies of non-COVID-19 severe respiratory viral infections provide indirect, very low-quality evidence that raises the possibility that convalescent plasma has minimal or no benefit in the treatment of COVID-19 and low-quality evidence that it does not cause serious adverse events.