Casadevall, Arturo

ABSTRACT Anti‐Spike monoclonal antibodies (mAbs) progressively lost efficacy during the COVID‐19 pandemic due to the emergence and predominance of resistant SARS‐CoV‐2 variants. By contrast, high‐titre COVID‐19 convalescent plasma (CCP) collected from vaccinated donors recently recovered from infection provides a polyclonal source of antibodies that remains effective in clearing SARS‐CoV‐2 in immunosuppressed patients, unable to mount an adequate immune response against the virus. We conducted a systematic review and individual participant data meta‐analysis to examine the effect of CCP in immunocompromised patients persistently positive for SARS‐CoV‐2 viraemia following mAb therapy, and to evaluate possible biological factors associated with a favourable outcome. Electronic databases were searched for studies published from January 2020 to January 2026. All studies including eligible cases were considered in the systematic review. Unpublished cases were also collected from investigators of the selected studies. The protocol was registered at PROSPERO (CRD420251142891). Forty‐seven cases (30 cases from 12 published studies and 17 unpublished cases) were included. In 33 out of 47 patients (70.2%) with a mAb‐resistant infection, SARS‐CoV‐2 clearance occurred following CCP transfusion, with a mean of 2.7 CCP units administered. In logistic regression, total CCP volume transfused was positively associated with SARS‐CoV‐2 clearance. In conclusion, CCP transfusion was associated with SARS‐CoV‐2 clearance in persistently positive immunocompromised patients following failure of anti‐Spike mAb therapy.

SUMMARY COVID-19 convalescent plasma (CCP) was the first specific therapy deployed for treating SARS-CoV-2 infection. CCP was successfully deployed in both resource-poor and resource-rich countries, establishing that convalescent plasma (CP) is a feasible option for combating the next pandemic. CCP reduced mortality and progression to hospitalization when used early in the disease with high-titer units. This knowledge was gained from a worldwide effort that included more than 50 countries. However, the deployment of CCP was haphazard and varied among countries. Clinical studies suffered from a lack of standardization regarding study design, CCP antibody dosing, timing of administration, and participant disease severity. Unfortunately, the hard-won knowledge from the serum therapy era in the early 20th century, which indicated that effective antibody therapy requires early use in the disease with a sufficient antibody dose, was largely forgotten. Many studies tested CCP late in the disease or without sufficient antibody titer and thus reported negative findings. Trial heterogeneity made it difficult to combine the results of studies. However, despite tremendous heterogeneity in study design and participant populations, meta-analysis revealed strong signals of efficacy when given early with high antiviral-specific antibody levels. When the next pandemic occurs, humanity is likely to resort to CP again. To avoid another chaotic rollout, planning for CP use should begin well before that emergency arrives and must involve both physician education on the principles of antibody therapy and clinical trial designs that test its efficacy in optimal conditions, which include early use with sufficient antibody doses.

In the Spring of 2020, the United States of America (USA) deployed COVID-19 convalescent plasma (CCP) to treat hospitalized patients. Over 500,000 patients were treated with CCP during the first year of the pandemic. In this study, we estimated the number of actual inpatient lives saved by CCP treatment in the United States of America based on CCP weekly use, weekly national mortality data, and CCP mortality reduction data from meta-analyses of randomized controlled trials and real-world data. We also estimate the potential number of lives saved if CCP had been deployed for 100% of hospitalized patients or used in 15 to 75% of outpatients. Depending on the assumptions modeled in stratified analyses, we estimated that CCP saved between 16,476 and 66,296 lives. The CCP ideal use might have saved as many as 234,869 lives and prevented 1,136,133 hospitalizations. CCP deployment was a successful strategy for ameliorating the impact of the COVID-19 pandemic in the USA. This experience has important implications for convalescent plasma use in future infectious disease emergencies.

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.

AbstractInfluenzavirus is among the most relevant candidates for a next pandemic. We review here the phylogeny of former influenza pandemics, and discuss candidate lineages. After briefly reviewing the other existing antiviral options, we discuss in detail the evidences supporting the efficacy of passive immunotherapies against influenzavirus, with a focus on convalescent plasma.

Plasma collected from people recovered from COVID-19 (COVID-19 convalescent plasma, CCP) was the first antibody-based therapy employed to fight the pandemic. CCP was, however, often employed in combination with other drugs, such as the antiviral remdesivir and glucocorticoids. The possible effect of such interaction has never been investigated systematically. To assess the safety and efficacy of CCP combined with other agents for treatment of patients hospitalized for COVID-19, a systematic literature search using appropriate Medical Subject Heading (MeSH) terms was performed through PubMed, EMBASE, Cochrane central, medRxiv and bioRxiv. The main outcomes considered were mortality and safety of CCP combined with other treatments versus CCP alone. This review was carried out in accordance with Cochrane methodology including risk of bias assessment and grading of the quality of evidence. Measure of treatment effect was the risk ratio (RR) together with 95% confidence intervals (CIs). A total of 11 studies (8 randomized controlled trials [RCTs] and 3 observational) were included in the systematic review, 4 studies with CCP combined with remdesivir and 6 studies with CCP combined with corticosteroids, all involving hospitalized patients. One RCT reported information on both remdesivir and steroids use with CCP. The use of CCP combined with remdesivir was associated with a significantly reduced risk of death (RR 0.74; 95% CI 0.56–0.97; p = 0.03; moderate certainty of evidence), while the use of steroids with CCP did not modify the mortality risk (RR 0.72; 95% CI 0.34–1.51; p = 0.38; very low certainty of evidence). Not enough safety data were retrieved form the systematic literature analysis. The current evidence from the literature suggests a potential beneficial effect on mortality of combined CCP plus remdesivir compared to CCP alone in hospitalized COVID-19 patients. No significant clinical interaction was found between CCP and steroids.

ABSTRACT In the United States (US), biosafety and biosecurity oversight of research on viruses is being reappraised. Safety in virology research is paramount and oversight frameworks should be reviewed periodically. Changes should be made with care, however, to avoid impeding science that is essential for rapidly reducing and responding to pandemic threats as well as addressing more common challenges caused by infectious diseases. Decades of research uniquely positioned the US to be able to respond to the COVID-19 crisis with astounding speed, delivering life-saving vaccines within a year of identifying the virus. We should embolden and empower this strength, which is a vital part of protecting the health, economy, and security of US citizens. Herein, we offer our perspectives on priorities for revised rules governing virology research in the US.