Trial design and supervision
We conducted a randomized, double-blind, placebo-controlled trial between 4 June 2020 and 25 October 2020 (when the last patient completed the follow-up) at clinical sites and geriatric units in Argentina. The trial was approved by the institutional review boards of the participating institutions and the state of Buenos Aires and is overseen by an independent data and security monitoring board. The authors who designed the essay and wrote the manuscript are listed in Table S15 in the supplementary appendix, with the full text of this article available at NEJM.org. All authors compiled the data and voted for the accuracy and completeness of the data and compliance with the trial by protocol, available on NEJM.org. Three of the authors analyzed the data. The last author wrote the first draft of the manuscript. No one who is not an author contributed to the writing of the manuscript. There are no confidentiality agreements regarding the information between the sponsors and the authors or their institutions.
Hearing patients
Patients who were 75 years or older, regardless of current coexisting conditions, or between 65 and 74 years of age with at least one concurrent condition, were identified and assessed for suitability. Coexisting conditions, as described in Table S1, included hypertension or diabetes for which the patient was currently receiving pharmacological treatment, obesity, chronic renal failure, cardiovascular disease, and COPD. At the time of screening for SARS-CoV-2 by reverse transcription polymerase chain reaction (RT-PCR) test, eligible patients had at least one of each sign or symptom in the following two categories for less than 48 hours: a temperature of at least 37.5 ° C, unexplained sweating, or chills; and dry cough, shortness of breath, fatigue, myalgia, anorexia, sore throat, dysgeusia, anosmia or rhinorrhea. Exclusion criteria included severe respiratory disease (the primary endpoint), any disease in Table S5, or both.
Patients given permission to undergo screening received home visits, and samples of nasopharyngeal and oropharyngeal secretions were obtained for testing with an RT-PCR test (iAMP COVID-19, Atila BioSystems) to detect SARS-CoV-2 track. Patients with detectable SARS-CoV-2 RNA were transported to trial hospitals and were invited to sign the informed consent form. After July 22, 2020, legal guardians granted permission for patients with cognitive impairment. As several geriatric institutions with SARS-CoV-2 outbreaks were transformed on 27 July 2020 into low-complexity inpatient units for mildly ill residents infected with SARS-CoV-2, we selected residents who met the trial requirements and invited to participate. in the trial on the spot.
Randomization and intervention
Eligible patients who gave written informed consent were randomly assigned to receive 250 ml recovery plasma with an IgG titer greater than 1: 1000 against SARS-CoV-2 spike (S) protein (COVIDAR IgG, Instituto Leloir, Argentina ) or 250 ml of placebo (0.9% normal saline). The restorative plasma is arbitrarily defined as ‘high titer’ and contains antibody concentrations in the upper 28th percentile. A computer-generated randomization series with a balanced permuted block design (block size 2) was prepared at the data center.
Recovery plasma or placebo was administered less than 72 hours after the onset of symptoms, and the infusions were given over a period of 1.5 to 2.0 hours. Both the recovery plasma and placebo were concealed with opaque bags and tape to cover the infusion catheter. Patients were monitored for adverse events up to 12 hours after the intervention.
A total of 479 potential plasma donors who had SARS-CoV-2 infection for a minimum of 10 days and who were asymptomatic for 3 days or longer and had two negative RT-PCR tests17 was identified through hospital listings and an online campaign. Potential donors who gave written informed consent were visited at home and screened for SARS-CoV-2 S IgG at a titer greater than 1: 1000 in serum. Each of the 135 candidates (28%) with sufficient titers donated 750 ml of plasma (see Fig. S6).
Clinical and laboratory monitoring
A total of 24 hours after the end of the infusion, a sample of venous blood (5 ml) was obtained from the patients. Serum samples were stored at -20 ° C until the experiment was completed. We tested anti-S IgG SARS-CoV-2 using the COVIDAR IgG test. In addition, we examined samples using the SARS-CoV-2 Spike S1-RBD IgG enzyme-linked immunosorbent detection kit (GenScript) and the SARS-CoV-2 surrogate virus neutralization test kit (GenScript).
The clinical status of the patients was monitored daily until day 15 by trial physicians to determine if the primary endpoint events were in the hospital, in participating geriatric institutions, or at home when the patients were discharged (Figs. S7 and S8). Patients who had persistent symptoms for which medical care was warranted were followed up until the resolution of the symptoms or for a maximum of 25 days to determine for secondary endpoint events. The trial physicians used pre-designed questionnaires to gather clinical information. None of the patients had any experimental therapy for Covid-19 except for recovery plasma. Data were recorded on paper forms and then duplicated in an electronic database.
Test endpoints
The primary endpoint of the trial was the development of severe respiratory illness, defined as a respiratory rate of 30 breaths per minute or more, an oxygen saturation of less than 93% while the patient inhales the air, or both. Patients were assessed for this endpoint event between 12 hours after infusion of recovery plasma or placebo and day 15 of the trial.
Predefined secondary clinical endpoints were life-threatening respiratory disease (defined as oxygen supplementation at a fraction of inspired oxygen [Fio2] of 100%, non-invasive or invasive ventilation, admission to an intensive care unit, or any combination thereof), critical systemic disease (respiratory failure with a ratio of the partial pressure of oxygen to Fio2 ≤200 mm Hg, shock, multiple organ dysfunction syndrome, or any combination thereof), and death associated with Covid-19. Patients in whom the disease did not resolve were assessed for these endpoint events until day 25 of participating in the trial. On July 22, 2020, we amended the protocol to include a fourth secondary endpoint that describes one of the three secondary endpoints above, alone or in combination.
Early trial termination
The trial began when the number of Covid-19 cases in Buenos Aires was high. However, as the number of cases decreased, it became clear that it would take about 5 months to reach the enrollment goal. Consequently, after discussions with the Data and Security Monitoring Board and the enrollment of 76% of the target population, we decided that it would be logistically impossible and ethically questionable, given the daily cost of the pandemic in lives and diseases, to continue the trial. sat, and we stopped to examine the results.
Statistical analysis
Given the complexity of implementing this intervention, the minimal clinically significant difference was determined at a 40% relative reduction for an expected 50% of patients in the placebo group and 30% of patients in the restorative plasma group receiving a primary end would have -point event. We estimate that a total sample size of 210 patients (105 per trial group) would provide the trial with 80% power to detect a difference between groups, at a significance level of α = 0.05. We use a two-sided z-test of relationships with continuity correction and one planned interim analysis with the O’Brien – Fleming spending function to determine the test limits.
In the analysis of the intention to treat, the endpoints were assessed from the time of randomization. Continuous variables are presented as averages and standard deviations or median and interquartile ranges, as appropriate, and categorical variables are presented as percentages.
In the primary analysis strategy, we used the Kaplan-Meier product limit estimates to compare the time to reach the primary endpoint in the experimental groups. An estimate of the relative risk and 95% confidence interval was also reported. A modified intention-for-treatment analysis excluded patients who were not eligible between randomization and the administration of recovery plasma or placebo.
The protocol proposed an evaluation of IgG protection correlates and a subgroup analysis proposed by the Data and Security Monitoring Board and approved by the Institutional Review Boards on 2 November 2020. This analysis included an evaluation of endpoint events in patients 75 years of age or older, regardless of existing conditions, and in those between 65 and 74 years of age who had at least one cohabiting condition.