Why will it never be known if convalescent plasma is effective for COVID-19

Convalescent plasma therapy in COVID-19: Unravelling the data using the principles of antibody therapy

INTRODUCTION

When the COVID-19 pandemic struck no specific therapies were available and many turned to COVID-19 convalescent plasma (CCP), a form of antibody therapy. The literature provides mixed evidence for CCP efficacy.

AREAS COVERED

PubMed was searched using the words COVID-19 and convalescent plasma and individual study designs were evaluated for adherence to the three principles of antibody therapy, i.e. that plasma 1) contain specific antibody; 2) have enough specific antibody to mediate a biological effect; and 3) be administered early in the course of disease. Using this approach, a diverse and seemingly contradictory collection of clinical findings was distilled into a consistent picture whereby CCP was effective when used according to the above principles of antibody therapy. In addition, CCP therapy in immunocompromised patients is useful at any time in the course of disease.

EXPERT OPINION

CCP is safe and effective when used appropriately. Today, most of humanity has some immunity to SARS-CoV-2 from vaccines and infection, which has lessened the need for CCP in the general population. However, COVID-19 in immunocompromised patients is a major therapeutic challenge, and with the deauthorization of all SARS-CoV-2-spike protein-directed monoclonal antibodies, CCP is the only antibody therapy available for this population.

Severe COVID-19: Drugs and Clinical Trials

By January of 2023, the COVID-19 pandemic had led to a reported total of 6,700,883 deaths and 662,631,114 cases worldwide. To date, there have been no effective therapies or standardized treatment schemes for this disease; therefore, the search for effective prophylactic and therapeutic strategies is a primary goal that must be addressed. This review aims to provide an analysis of the most efficient and promising therapies and drugs for the prevention and treatment of severe COVID-19, comparing their degree of success, scope, and limitations, with the aim of providing support to health professionals in choosing the best pharmacological approach. An investigation of the most promising and effective treatments against COVID-19 that are currently available was carried out by employing search terms including "Convalescent plasma therapy in COVID-19" or "Viral polymerase inhibitors" and "COVID-19" in the Clinicaltrials.gov and PubMed databases. From the current perspective and with the information available from the various clinical trials assessing the efficacy of different therapeutic options, we conclude that it is necessary to standardize certain variables-such as the viral clearance time, biomarkers associated with severity, hospital stay, requirement of invasive mechanical ventilation, and mortality rate-in order to facilitate verification of the efficacy of such treatments and to better assess the repeatability of the most effective and promising results.

A comprehensive review on pharmacologic agents, immunotherapies and supportive therapeutics for COVID-19

The emergence of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected many countries throughout the world. As urgency is a necessity, most efforts have focused on identifying small molecule drugs that can be repurposed for use as anti-SARS-CoV-2 agents. Although several drug candidates have been identified using in silico method and in vitro studies, most of these drugs require the support of in vivo data before they can be considered for clinical trials. Several drugs are considered promising therapeutic agents for COVID-19. In addition to the direct-acting antiviral drugs, supportive therapies including traditional Chinese medicine, immunotherapies, immunomodulators, and nutritional therapy could contribute a major role in treating COVID-19 patients. Some of these drugs have already been included in the treatment guidelines, recommendations, and standard operating procedures. In this article, we comprehensively review the approved and potential therapeutic drugs, immune cells-based therapies, immunomodulatory agents/drugs, herbs and plant metabolites, nutritional and dietary for COVID-19.

Systematic reviews of convalescent plasma in COVID-19 continue to be poorly conducted and reported: a systematic review

OBJECTIVES

To suggest possible approaches to combatting the impact of the COVID-19 infodemic to prevent research waste in future health emergencies and in everyday research and practice.

STUDY DESIGN AND SETTING

Systematic review. The Epistemonikos database was searched in June 2021 for systematic reviews on the effectiveness of convalescent plasma for COVID-19. Two reviewers independently screened the retrieved references with disagreements resolved by discussion. Data extraction was completed by one reviewer with a proportion checked by a second. We used the Assessment of Multiple Systematic Reviews to assess the quality of conduct and reporting of included reviews.

RESULTS

Fifty one systematic reviews are included with 193 individual studies included within the systematic reviews. There was considerable duplication of effort; multiple reviews were conducted at the same time with inconsistencies in the evidence included. The reviews were of low methodological quality, poorly reported, and did not adhere to preferred reporting items for systematic reviews and meta-analysis guidance.

CONCLUSION

Researchers need to conduct, appraise, interpret, and disseminate systematic reviews better. All in the research community (researchers, peer-reviewers, journal editors, funders, decision makers, clinicians, journalists, and the public) need to work together to facilitate the conduct of robust systematic reviews that are published and communicated in a timely manner, reducing research duplication and waste, increasing transparency and accessibility of all systematic reviews.

Targeted therapy in Coronavirus disease 2019 (COVID-19): Implication from cell and gene therapy to immunotherapy and vaccine

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) is a highly pathogenic and transmissible virus. Infection caused by SARS-CoV-2 known as Coronavirus disease 2019 (COVID-19) can be severe, especially among high risk populations affected of underlying medical conditions. COVID-19 is characterized by the severe acute respiratory syndrome, a hyper inflammatory syndrome, vascular injury, microangiopathy and thrombosis. Antiviral drugs and immune modulating methods has been evaluated. So far, a particular therapeutic option has not been approved for COVID-19 and a variety of treatments have been studied for COVID-19 including, current treatment such as oxygen therapy, corticosteroids, antiviral agents until targeted therapy and vaccines which are diverse in each patient and have various outcomes. According to the findings of different in vitro and in vivo studies, some novel approach such as gene editing, cell based therapy, and immunotherapy may have significant potential in the treatment of COVID-19. Based on these findings, this paper aims to review the different strategies of treatment against COVID-19 and provide a summary from traditional and newer methods in curing COVID-19.

Safety and efficacy of convalescent plasma for severe COVID-19: a randomized, single blinded, parallel, controlled clinical study

Background

Convalescent plasma (CP) has been widely used to treat COVID-19 and is under study. However, the variability in the current clinical trials has averted its wide use in the current pandemic. We aimed to evaluate the safety and efficacy of CP in severe coronavirus disease 2019 (COVID-19) in the early stages of the disease.

Methods

A randomized controlled clinical study was conducted on 101 patients admitted to the hospital with confirmed severe COVID-19. Most participants had less than 14 days from symptoms onset and less than seven days from hospitalization. Fifty patients were assigned to receive CP plus standard therapy (ST), and 51 were assigned to receive ST alone. Participants in the CP arm received two doses of 250 mL each, transfused 24 h apart. All transfused plasma was obtained from "super donors" that fulfilled the following criteria: titers of anti-SARS-CoV-2 S1 IgG ≥ 1:3200 and IgA ≥ 1:800 antibodies. The effect of transfused anti-IFN antibodies and the SARS-CoV-2 variants at the entry of the study on the overall CP efficacy was evaluated. The primary outcomes were the reduction in viral load and the increase in IgG and IgA antibodies at 28 days of follow-up. The per-protocol analysis included 91 patients.

Results

An early but transient increase in IgG anti-S1-SARS-CoV-2 antibody levels at day 4 post-transfusion was observed (Estimated difference [ED], − 1.36; 95% CI, − 2.33 to − 0.39; P = 0.04). However, CP was not associated with viral load reduction in any of the points evaluated. Analysis of secondary outcomes revealed that those patients in the CP arm disclosed a shorter time to discharge (ED adjusted for mortality, 3.1 days; 95% CI, 0.20 to 5.94; P = 0.0361) or a reduction of 2 points on the WHO scale when compared with the ST group (HR adjusted for mortality, 1.6; 95% CI, 1.03 to 2.5; P = 0.0376). There were no benefits from CP on the rates of intensive care unit admission (HR, 0.82; 95% CI, 0.35 to 1.9; P = 0.6399), mechanical ventilation (HR, 0.66; 95% CI, 0.25 to 1.7; P = 0.4039), or mortality (HR, 3.2; 95% CI, 0.64 to 16; P = 0.1584). Anti-IFN antibodies and SARS-CoV-2 variants did not influence these results.

Conclusion

CP was not associated with viral load reduction, despite the early increase in IgG anti-SARS-CoV-2 antibodies. However, CP is safe and could be a therapeutic option to reduce the hospital length of stay.

Trial registration NCT04332835

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07560-7.

Human Intramuscular Hyperimmune Gamma Globulin (hIHGG) Anti-SARS-CoV-2-Characteristics of Intermediates and Final Product

This study aims to characterize the intermediates, and the final product (FP) obtained during the production of human intramuscular hyperimmune gamma globulin anti-SARS-CoV-2 (hIHGG anti-SARS-CoV-2) and to determine its stability. Material and methods: hIHGG anti-SARS-CoV-2 was fractionated from 270 convalescent plasma donations with the Cohn method. Prior to fractionation, the plasma was inactivated (Theraflex MB Plasma). Samples were defined using enzyme immunoassays (EIA) for anti-S1, anti-RBD S1, and anti-N antibodies, and neutralization assays with SARS-CoV-2 (VN) and pseudoviruses (PVN, decorated with SARS-CoV-2 S protein). Results were expressed as a titer (EIA) or 50% of the neutralization titer (IC50) estimated in a four-parameter nonlinear regression model. Results: Concentration of anti-S1 antibodies in plasma was similar before and after inactivation. Following fractionation, the anti-S1, anti-RBD, and anti-N (total tests) titers in FP were concentrated approximately 15-fold from 1:4 to 1:63 (1800 BAU/mL), 7-fold from 1:111 to 1:802 and from 1:13 to 1:88, respectively. During production, the IgA (anti-S1) antibody titer was reduced to an undetectable level and the IgM (anti-RBD) titer from 1:115 to 1:24. The neutralizing antibodies (nAb) titer increased in both VN (from 1:40 to 1:160) and PVN (IC50 from 63 to 313). The concentration of specific IgG in the FP did not change significantly for 14 months. Conclusions: The hIHGG anti-SARS-CoV-2 was stable, with concentration up to approximately 15-fold nAb compared to the source plasma pool.

Anti-SARS-CoV-2 and anti-cytokine storm neutralizing antibody therapies against COVID-19: Update, challenges, and perspectives

Coronavirus disease 2019 (COVID-19) has been declared by the World Health Organization (WHO) as a pandemic since March 2020. This disease is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The only available tools to avoid contamination and transmission of this virus are physical distancing, the use of N95 and surgical masks, and hand hygiene. Vaccines are another essential tool to reduce the impact of the pandemic, though these present challenges in terms of production and logistics, particularly in underdeveloped and developing countries. One of the critical early research findings is the interaction of the spike virus protein with the angiotensin-converting enzyme 2 (ACE2) human receptor. Developing strategies to block this interaction has therefore been identified as a way to treat this infection. Neutralizing antibodies (nAbs) have emerged as a therapeutic approach since the pandemic started. Infected patients may be asymptomatic or present with mild symptoms, and others may evolve to moderate or severe disease, leading to death. An immunological phenomenon known as cytokine storm has been observed in patients with severe disease characterized by a proinflammatory cytokine cascade response that leads to lung injury. Thus, some treatment strategies focus on anti-cytokine storm nAbs. This review summarizes the latest advances in research and clinical trials, challenges, and perspectives on antibody-based treatments (ABT) as therapies against COVID-19.

Detection of SARS-CoV-2-independent immunoregulatory activity of COVID-19 convalescent plasma

BACKGROUND

Convalescent plasma has emerged as a potential specific treatment for coronavirus disease 2019 (COVID-19), since it contains severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. Several studies are currently investigating the efficacy of convalescent plasma for treatment of COVID-19, with a focus on neutralizing antibodies. However, there is little information on whether convalescent plasma may contain additional immunoregulatory constituents produced by the blood donor during convalescence. Therefore, using a standardized whole blood assay employing synthetic toll-like receptor (TLR) ligands, we have investigated the immunoregulatory capacity of convalescent plasma in direct comparison to ABO-matched allogeneic control plasma.

STUDY DESIGN AND METHODS

Whole blood samples from healthy blood donors were collected, and autologous plasma was replaced by convalescent plasma or ABO-matched control plasma. Standardized innate immune triggering and monitoring was performed by adding different TLR ligands (Pam3CsK4 [TLR1/2], HKLM [TLR2], LPS [TLR4], flagellin [TLR5], ssRNA40 [TLR8], imiquimod [TLR7], and FSL-1 [TLR2/6]) and subsequent quantitative analysis of pro- and anti-inflammatory cytokines (IP-10, IL-1β, TNF-α, MCP-1, IL-6, IL-10, and IFN-γ) by cytometric bead array. Negative controls included unstimulated samples as well as samples spiked with autologous plasma.

RESULTS

COVID-19 convalescent plasma (CCP) significantly decreased pro-inflammatory cytokines production triggered by different TLR ligands in healthy donors as compared with healthy control plasma. IL-6, MCP-1, and IFN-γ represented the cytokines that are most frequently downregulated by convalescent plasma.

CONCLUSION

Our experiments reveal a potential novel, SARS-CoV-2-independent immunomodulatory activity of CCP, which may be beneficial for COVID-19 patients.

Early Convalescent Plasma Therapy and Mortality Among US Veterans Hospitalized With Nonsevere COVID-19: An Observational Analysis Emulating a Target Trial

BACKGROUND

Early convalescent plasma transfusion may reduce mortality in patients with nonsevere coronavirus disease 2019 (COVID-19).

METHODS

This study emulates a (hypothetical) target trial using observational data from a cohort of US veterans admitted to a Department of Veterans Affairs (VA) facility between 1 May and 17 November 2020 with nonsevere COVID-19. The intervention was convalescent plasma initiated within 2 days of eligibility. Thirty-day mortality was compared using cumulative incidence curves, risk differences, and hazard ratios estimated from pooled logistic models with inverse probability weighting to adjust for confounding.

RESULTS

Of 11 269 eligible person-trials contributed by 4755 patients, 402 trials were assigned to the convalescent plasma group. Forty and 671 deaths occurred within the plasma and nonplasma groups, respectively. The estimated 30-day mortality risk was 6.5% (95% confidence interval [CI], 4.0%-9.7%) in the plasma group and 6.2% (95% CI, 5.6%-7.0%) in the nonplasma group. The associated risk difference was 0.30% (95% CI, -2.30% to 3.60%) and the hazard ratio was 1.04 (95% CI, .64-1.62).

CONCLUSIONS

Our target trial emulation estimated no meaningful differences in 30-day mortality between nonsevere COVID-19 patients treated and untreated with convalescent plasma. Clinical Trials Registration. NCT04545047.

Preparedness and activities of the anti-SARS-CoV-2 convalescent plasma bank in the Veneto region (Italy): An organizational model for future emergencies

Background

Convalescent plasma (CP) has been used in the past in various pandemics, in particular in H1N1, SARS and MERS infections. In Spring 2020, when ongoing the SARS-CoV-2 pandemics, the Veneto Region (V-R) has proposed setting-up an anti-SARS-CoV-2 CP (CCP) Bank, with the aim of preparing a supply of CCP immediately available in case of subsequest epidemic waves.

Materials and Methods

Key-points to be developed for a quick set-up of the V-R CCP Bank have been recruitment of donors recovered from COVID-19 infection, laboratory analysis for the biological qualification of the CCP units, including titre of neutralizing antibodies and reduction of pathogens, according to National Blood Centre (CNS) Directives, adaptation of the V-R Information Technology systems and cost analysis. Some activities, including diagnostic and viral inactivation processes, have been centralized in 2 or 3 sites. Laboratory analysis upon preliminary admission of the donor included all tests required by the Italian laws and the CNS directives.

Results

From April to August 2020, 3,298 people have contacted the V-R Blood Transfusion Services: of these, 1,632 have been evaluated and examined as first time donors and those found to be suitable have carried out 955 donations, from which 2,626 therapeutic fractions have been obtained, at a cost around 215,00 Euro. Since October 2020, the number of COVID-19 inpatients has had a surge with a heavy hospital overload. Moreover, the high request of CCP therapy by clinicians has been just as unexpected, showing a wide therapeutic use.

Conclusions

The organizational model here presented, which has allowed the rapid collection of a large amount of CCP, could be useful when facing new pandemic outbreaks, especially in low and middle income countries, with generally acceptable costs.

Immunotherapy for COVID-19: Evolving treatment of viral infection and associated adverse immunological reactions

This review on COVID-19 immunotherapy enables a comparative analysis of the short-list of currently approved major vaccines. These include the Pfizer and Moderna first mRNA vaccines under FDA purview and the Oxford/AstraZeneca simian adenovirus-vectored vaccine (under UK-MHPRA guidance), all produced in record time, being safe and effective. The Pfizer and Moderna double dose vaccines have the clear edge in treatment efficacy, being in the 90% range compared to AstraZeneca in the average 70%. However, the AZ double dose vaccine has significant advantages with respect to lower cost and stability in storage. We enumerate several potential advances in the technology of the manufacturers: (1) combination vaccines such as testing AstraZeneca's product with a component of the Russian's Sputnik V to achieve durable immunity; (2) the potential for single dose vaccines coming on-line, and with Johnson & Johnson/Janssen; and (3) the need for refined thermotolerant formulations obviating the need for cold storage. As an adjunct to vaccinotherapy, affinity adsorption column technology is another facet recruited in the processing of corona convalescent plasma/cryosupernatant to concentrate neutralizing antibodies against the virus. Clinical trials, to date, of infected patients have been indeterminate as to whether plasmapheresis-based products are effective or not. This is due to the failure to standardize the composition of the plasma derived component, ambiguous clinical indications for use in human subjects, and inconsistent timing of administration in the course of the infection. Known T-cell lymphopenia, which is attendant to progressive viral infection and immune driven inflammation, may be a quantitative surrogate biological marker as to when to start treatment. This is not only for initiating plasmapheresis-based therapeutics but also the judicious selection of ancillary pharmaceuticals, ie. monoclonal antibodies, recombinant proteins and anti-viral drugs.

COVID-19 convalescent plasma composition and immunological effects in severe patients

Convalescent plasma (CP) has emerged as a treatment for COVID-19. However, the composition and mechanism of action are not fully known. Therefore, we undertook a two-phase controlled study in which, first the immunological and metabolomic status of recovered and severe patients were evaluated. Secondly, the 28-day effect of CP on the immune response in severe patients was assessed. Nineteen recovered COVID-19 patients, 18 hospitalized patients with severe disease, and 16 pre-pandemic controls were included. Patients with severe disease were treated with CP transfusion and standard therapy (i.e., plasma recipients, n = 9) or standard therapy alone (n = 9). Clinical and biological assessments were done on day 0 and during follow-up on days 4, 7, 14, and 28. Clinical parameters, viral load, total immunoglobulin (Ig) G and IgA anti-S1-SARS-CoV-2 antibodies, neutralizing antibodies (NAbs), autoantibodies, cytokines, T and B cells, and metabolomic and lipidomic profiles were examined. Total IgG and IgA anti-S1-SARS-CoV-2 antibodies were key factors for CP selection and correlated with NAbs. In severe COVID-19 patients, mostly interleukin (IL)-6 (P = <0.0001), IL-10 (P = <0.0001), IP-10 (P = <0.0001), fatty acyls and glycerophospholipids were higher than in recovered patients. Latent autoimmunity and anti-IFN-α antibodies were observed in both recovered and severe patients. COVID-19 CP induced an early but transient cytokine profile modification and increases IgG anti-S1-SARS-CoV-2 antibodies. At day 28 post-transfusion, a decrease in activated, effector and effector memory CD4+ (P < 0.05) and activated and effector CD8+ (P < 0.01) T cells and naïve B cells (P = 0.001), and an increase in non-classical memory B cells (P=<0.0001) and central memory CD4+ T cells (P = 0.0252) were observed. Moreover, IL-6/IFN-γ (P = 0.0089) and IL-6/IL-10 (P = 0.0180) ratios decreased in plasma recipients compared to those who received standard therapy alone. These results may have therapeutic implications and justify further post-COVID-19 studies.

Manufacturing of convalescent plasma of COVID-19 patients: Aspects of quality

The ongoing coronavirus disease 2019 (COVID-19) pandemic emerged in December 2019. Convalescent plasma represents a promising COVID-19 treatment. Here, we report on the manufacturing of a plasma-based product containing antibodies specific to SARS-CoV-2 obtained from recently recovered COVID-19 patients. Convalescent plasma donors were screened as follows: 1) previously confirmed SARS-CoV-2 infection (by real-time PCR (RT-PCR)); 2) a subsequent negative PCR test followed by a 2-week waiting period; 3) an additional negative PCR test prior to plasmapheresis; and 4) confirmation of the presence of SARS-CoV-2 specific antibodies. Convalescent plasma was stored fresh (2-6°C) for up to 5 days or frozen (-30°C) for long-term storage. Donor peripheral blood and final plasma product were assayed for binding antibodies targeting the SARS-CoV-2 S-protein receptor-binding domain (RBD) and their titers measured by an enzyme-linked immunosorbent assay (ELISA). We performed 72 plasmaphereses resulting in 248 final products. Convalescent plasma contained an RBD-specific antibody titer (IgG) ranging from 1:100 to 1:3200 (median 1:800). The titer was congruent to the titer of the blood (n = 34) before collection (1:100-1:6400, median 1:800). Levels of IL-8 and LBP of donors were slightly increased. Therapeutic products derived from a human origin must undergo rigorous testing to ensure uniform quality and patient safety. Whilst previous publications recommended RBD-specific binding antibody titers of ≥ 1:320, we selected a minimum titer of 1:800 in order to maximize antibody delivery. Production of highly standardized convalescent plasma was safe, feasible and was readily implemented in the treatment of severely ill COVID-19 patients.