Early Outpatient Treatment for Covid-19 with Convalescent Plasma.

BACKGROUND: Polyclonal convalescent plasma may be obtained from donors who have recovered from coronavirus disease 2019 (Covid-19). The efficacy of this plasma in preventing serious complications in outpatients with recent-onset Covid-19 is uncertain. METHODS: In this multicenter, double-blind, randomized, controlled trial, we evaluated the efficacy and safety of Covid-19 convalescent plasma, as compared with control plasma, in symptomatic adults (≥18 years of age) who had tested positive for severe acute respiratory syndrome coronavirus 2, regardless of their risk factors for disease progression or vaccination status. Participants were enrolled within 8 days after symptom onset and received a transfusion within 1 day after randomization. The primary outcome was Covid-19-related hospitalization within 28 days after transfusion. RESULTS: Participants were enrolled from June 3, 2020, through October 1, 2021. A total of 1225 participants underwent randomization, and 1181 received a transfusion. In the prespecified modified intention-to-treat analysis that included only participants who received a transfusion, the primary outcome occurred in 17 of 592 participants (2.9%) who received convalescent plasma and 37 of 589 participants (6.3%) who received control plasma (absolute risk reduction, 3.4 percentage points; 95% confidence interval, 1.0 to 5.8; P = 0.005), which corresponded to a relative risk reduction of 54%. Evidence of efficacy in vaccinated participants cannot be inferred from these data because 53 of the 54 participants with Covid-19 who were hospitalized were unvaccinated and 1 participant was partially vaccinated. A total of 16 grade 3 or 4 adverse events (7 in the convalescent-plasma group and 9 in the control-plasma group) occurred in participants who were not hospitalized. CONCLUSIONS: In participants with Covid-19, most of whom were unvaccinated, the administration of convalescent plasma within 9 days after the onset of symptoms reduced the risk of disease progression leading to hospitalization. (Funded by the Department of Defense and others; CSSC-004 ClinicalTrials.gov number, NCT04373460.).

Passive immunotherapies for the next influenza pandemic.

Influenzavirus 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.

Analysis of SARS-CoV-2 mutations associated with resistance to therapeutic monoclonal antibodies that emerge after treatment.

The mutation rate of the Omicron sublineage has led to baseline resistance against all previously authorized anti-Spike monoclonal antibodies (mAbs). Nevertheless, in case more antiviral mAbs will be authorized in the future, it is relevant to understand how frequently treatment-emergent resistance has emerged so far, under different combinations and in different patient subgroups. We report the results of a systematic review of the medical literature for case reports and case series for treatment-emergent immune escape, which is defined as emergence of a resistance-driving mutation in at least 20% of sequences in a given host at a given timepoint. We identified 32 publications detailing 216 cases that included different variants of concern (VOC) and found that the incidence of treatment emergent-resistance ranged from 10% to 50%. Most of the treatment-emergent resistance events occurred in immunocompromised patients. Interestingly, resistance also emerged against cocktails of two mAbs, albeit at lower frequencies. The heterogenous therapeutic management of those cases doesn't allow inferences about the clinical outcome in patients with treatment-emergent resistance. Furthermore, we noted a temporal correlation between the introduction of mAb therapies and a subsequent increase in SARS-CoV-2 sequences across the globe carrying mutations conferring resistance to that mAb, raising concern as to whether these had originated in mAb-treated individuals. Our findings confirm that treatment-emergent immune escape to anti-Spike mAbs represents a frequent and concerning phenomenon and suggests that these are associated with mAb use in immunosuppressed hosts.

Plasmodium berghei Purified Hemozoin Associated with DNA Strongly Inhibits P. berghei Liver-Stage Development in BALB/c Mice after Intravenous Inoculation.

In the acidic lysosome-like digestive vacuole, Plasmodium parasites crystallize heme from hemoglobin into hemozoin, or malaria pigment. Upon release of progeny merozoites, the residual hemozoin is phagocytized by macrophages principally in the liver and spleen where the heme crystals can persist for months to years, as heme oxygenase does not readily degrade the crystal. Previous studies demonstrated hemozoin modulation of monocytes and macrophages. Hemozoin modulates immune function activity of monocytes/macrophages. Here, we used purified/washed hemozoin (W-Hz) isolated from murine Plasmodium berghei infections and intravenously (i.v.) injected it back into naive mice. We characterized the modulating effect of W-Hz on liver-stage replication. Purified washed hemozoin decreases P. berghei liver levels both at 1 week and 1 month after i.v. injection in a dose and time dependent fashion. The injected hemozoin fully protected in nine out of 10 mice given a 50 sporozoite inoculum, and in 10 out of 10 mice against 2,000 sporozoites when they were infected an hour or a day after hemozoin inoculation. DNase treatment at the hemozoin reversed the observed liver load reduction. The liver load reduction was similar in mature B- and T-cell-deficient RAG-1 knockout (KO) mice suggesting an innate immune protection mechanism. This work indicates a role for residual hemozoin in down modulation of Plasmodium liver stages.

Coronavirus Disease 2019 Convalescent Plasma Utilization in the United States: Data From the National Inpatient Sample.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CCP) use between October and December 2020 was characterized using the National Inpatient Sample database. CCP was administered in 18.0% of COVID-19-associated hospitalizations and was strongly associated with older age and increased disease severity. There were disparities in the receipt of CCP by race and ethnicity, geography, and insurance.

Guidance on the Use of Convalescent Plasma to Treat Immunocompromised Patients With Coronavirus Disease 2019.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CCP) is a safe and effective treatment for COVID-19 in immunocompromised (IC) patients. IC patients have a higher risk of persistent infection, severe disease, and death from COVID-19. Despite the continued clinical use of CCP to treat IC patients, the optimal dose, frequency/schedule, and duration of CCP treatment has yet to be determined, and related best practices guidelines are lacking. A group of individuals with expertise spanning infectious diseases, virology and transfusion medicine was assembled to render an expert opinion statement pertaining to the use of CCP for IC patients. For optimal effect, CCP should be recently and locally collected to match circulating variant. CCP should be considered for the treatment of IC patients with acute and protracted COVID-19; dosage depends on clinical setting (acute vs protracted COVID-19). CCP containing high-titer severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies, retains activity against circulating SARS-CoV-2 variants, which have otherwise rendered monoclonal antibodies ineffective.

Coronavirus Disease 2019 Convalescent Plasma Outpatient Therapy to Prevent Outpatient Hospitalization: A Meta-Analysis of Individual Participant Data From 5 Randomized Trials.

BACKGROUND: Outpatient monoclonal antibodies are no longer effective and antiviral treatments for coronavirus disease 2019 (COVID-19) disease remain largely unavailable in many countries worldwide. Although treatment with COVID-19 convalescent plasma (CCP) is promising, clinical trials among outpatients have shown mixed results. METHODS: We conducted an individual participant data meta-analysis from outpatient trials to assess the overall risk reduction for all-cause hospitalizations by day 28 in transfused participants. Relevant trials were identified by searching Medline, Embase, medRxiv, World Health Organization COVID-19 Research Database, Cochrane Library, and Web of Science from January 2020 to September 2022. RESULTS: Five included studies from 4 countries enrolled and transfused 2620 adult patients. Comorbidities were present in 1795 (69%). The virus neutralizing antibody dilutional titer levels ranged from 8 to 14 580 in diverse assays. One hundred sixty of 1315 (12.2%) control patients were hospitalized, versus 111 of 1305 (8.5%) CCP-treated patients, yielding a 3.7% (95% confidence interval [CI], 1.3%-6.0%; P = .001) absolute risk reduction and 30.1% relative risk reduction for all-cause hospitalization. The hospitalization reduction was greatest in those with both early transfusion and high titer with a 7.6% absolute risk reduction (95% CI, 4.0%-11.1%; P = .0001) accompanied by at 51.4% relative risk reduction. No significant reduction in hospitalization was seen with treatment >5 days after symptom onset or in those receiving CCP with antibody titers below the median titer. CONCLUSIONS: Among outpatients with COVID-19, treatment with CCP reduced the rate of all-cause hospitalization and may be most effective when given within 5 days of symptom onset and when antibody titer is higher.

Plasma after both SARS-CoV-2 boosted vaccination and COVID-19 potently neutralizes BQ.1.1 and XBB.1.

Recent 2022 SARS-CoV-2 Omicron variants, have acquired resistance to most neutralizing anti-Spike monoclonal antibodies authorized, and the BQ.1.* sublineages are notably resistant to all authorized monoclonal antibodies. Polyclonal antibodies from individuals both vaccinated and recently recovered from Omicron COVID-19 (VaxCCP) could retain new Omicron neutralizing activity. Here we reviewed BQ.1.* virus neutralization data from 920 individual patient samples from 43 separate cohorts defined by boosted vaccinations (Vax) with or without recent Omicron COVID-19, as well as infection without vaccination (CCP) to determine level of BQ.1.* neutralizing antibodies and percent of plasma samples with neutralizing activity. More than 90 % of the plasma samples from individuals in the recently (within 6 months) boosted VaxCCP study cohorts neutralized BQ.1.1, and BF.7 with 100 % neutralization of WA-1, BA.4/5, BA.4.6 and BA.2.75. The geometric mean of the geometric mean 50 % neutralizing titres (GM (GMT50) were 314, 78 and 204 for BQ.1.1, XBB.1 and BF.7, respectively. Compared to VaxCCP, plasma sampled from COVID-19 naïve subjects who also recently (within 6 months) received at least a third vaccine dose had about half of the GM (GMT50) for all viral variants. Boosted VaxCCP characterized by either recent vaccine dose or infection event within 6 months represents a robust, variant-resilient, neutralizing antibody source against the new Omicron BQ.1.1, XBB.1 and BF.7 variants.

Outpatient randomized controlled trials to reduce COVID-19 hospitalization: Systematic review and meta-analysis.

This COVID-19 outpatient randomized controlled trials (RCTs) systematic review compares hospitalization outcomes amongst four treatment classes over pandemic period, geography, variants, and vaccine status. Outpatient RCTs with hospitalization endpoint were identified in Pubmed searches through May 2023, excluding RCTs <30 participants (PROSPERO-CRD42022369181). Risk of bias was extracted from COVID-19-NMA, with odds ratio utilized for pooled comparison. Searches identified 281 studies with 61 published RCTs for 33 diverse interventions analyzed. RCTs were largely unvaccinated cohorts with at least one COVID-19 hospitalization risk factor. Grouping by class, monoclonal antibodies (mAbs) (OR = 0.31 [95% CI = 0.24-0.40]) had highest hospital reduction efficacy, followed by COVID-19 convalescent plasma (CCP) (OR = 0.69 [95% CI = 0.53-0.90]), small molecule antivirals (OR = 0.78 [95% CI = 0.48-1.33]), and repurposed drugs (OR = 0.82 [95% CI: 0.72-0.93]). Earlier in disease onset interventions performed better than later. This meta-analysis allows approximate head-to-head comparisons of diverse outpatient interventions. Omicron sublineages (XBB and BQ.1.1) are resistant to mAbs Despite trial heterogeneity, this pooled comparison by intervention class indicated oral antivirals are the preferred outpatient treatment where available, but intravenous interventions from convalescent plasma to remdesivir are also effective and necessary in constrained medical resource settings or for acute and chronic COVID-19 in the immunocompromised.

A second mechanism employed by artemisinins to suppress Plasmodium falciparum hinges on inhibition of hematin crystallization.

Malaria is a pervasive disease that affects millions of lives each year in equatorial regions of the world. During the erythrocytic phase of the parasite life cycle, Plasmodium falciparum invades red blood cells, where it catabolizes hemoglobin and sequesters the released toxic heme as innocuous hemozoin crystals. Artemisinin (ART)-class drugs are activated in vivo by newly released heme, which creates a carbon-centered radical that markedly reduces parasite density. Radical damage to parasite lipids and proteins is perceived to be ARTs' dominant mechanism of action. By contrast, quinoline-class antimalarials inhibit the formation of hemozoin and in this way suppress heme detoxification. Here, we combine malaria parasite assays and scanning probe microscopy of growing ß-hematin crystals to elucidate an unexpected mechanism employed by two widely administered antimalarials, ART, and artesunate to subdue the erythrocytic phase of the parasite life cycle. We demonstrate that heme-drug adducts, produced after the radical activation of ARTs and largely believed to be benign bystanders, potently kills P. falciparum at low exogenous concentrations. We show that these adducts inhibit ß-hematin crystallization and heme detoxification, a pathway which complements the deleterious effect of radicals generated via parent drug activation. Our findings reveal an irreversible mechanism of heme-ART adduct inhibition of heme crystallization, unique among antimalarials and common crystal growth inhibitors, that opens new avenues for evaluating drug dosing regimens and understanding growing resistance of P. falciparum to ART.

Calibrating COVID-19 susceptible-exposed-infected-removed models with time-varying effectivecontact rates.

We describe the population-based susceptible-exposed-infected-removed (SEIR) model developed by the Irish Epidemiological Modelling Advisory Group (IEMAG), which advises the Irish government on COVID-19 responses. The model assumes a time-varying effective contact rate (equivalently, a time-varying reproduction number) to model the effect of non-pharmaceutical interventions. A crucial technical challenge in applying such models is their accurate calibration to observed data, e.g. to the daily number of confirmed new cases, as the history of the disease strongly affects predictions of future scenarios. We demonstrate an approach based on inversion of the SEIR equations in conjunction with statistical modelling and spline-fitting of the data to produce a robust methodology for calibration of a wide class of models of this type. This article is part of the theme issue 'Data science approaches to infectious disease surveillance'.

Lactic Acid Supplementation Increases Quantity and Quality of Gametocytes in Plasmodium falciparum Culture.

Malaria infection by Plasmodium falciparum continues to afflict millions of people worldwide, with transmission being dependent upon mosquito ingestion of the parasite gametocyte stage. These sexually committed stages develop from the asexual stages, yet the factors behind this transition are not completely understood. Here, we found that lactic acid increases gametocyte quantity and quality in P. falciparum culture. Low-passage-number NF54 parasites exposed to 8.2 mM lactic acid for various times were monitored using blood film gametocyte counts and RNA analysis throughout 2 weeks of gametocyte development in vitro for a total of 5 biological cohorts. We found that daily continuous medium exchange and 8.2 mM lactic acid supplementation increased gametocytemia approximately 2- to 6-fold relative to controls after 5 days. In membrane feeding mosquito infection experiments, we found that gametocytes continuously exposed to 8.2 mM lactic acid supplementations were more infectious to Anopheles stephensi mosquitoes, essentially doubling prevalence of infected midguts and oocyst density. Supplementation on days 9 to 16 did not increase the quantity of gametocytes but did increase quality, as measured by oocyst density, by 2.4-fold. Lactic acid did not impact asexual growth, as measured by blood film counts and luciferase quantification, as well as radioactive hypoxanthine incorporation assays. These data indicate a novel role for lactic acid in sexual development of the parasite.

In vivo compartmental kinetics of Plasmodium falciparum histidine-rich protein II in the blood of humans and in BALB/c mice infected with a transgenic Plasmodium berghei parasite expressing histidine-rich protein II.

BACKGROUND: The Plasmodium falciparum histidine-rich protein II (PfHRP2) is a common biomarker used in malaria rapid diagnostic tests (RDTs), but can persist in the blood for up to 40 days following curative treatment. The persistence of PfHRP2 presents a false positive limitation to diagnostic interpretation. However, the in vivo dynamics and compartmentalization underlying PfHRP2 persistence have not been fully characterized in the plasma and erythrocyte (RBC) fraction of the whole blood. METHODS: The kinetics and persistence of PfHRP2 in the plasma and RBC fractions of the whole blood were investigated post-treatment in human clinical samples and samples isolated from BALB/c mice infected with a novel transgenic Plasmodium berghei parasite engineered to express PfHRP2 (PbPfHRP2). RESULTS: PfHRP2 levels in human RBCs were consistently 20-40 times greater than plasma levels, even post-parasite clearance. PfHRP2 positive, DNA negative, once-infected RBCs were identified in patients that comprised 0.1-1% of total RBCs for 6 and 12 days post-treatment, even post-atovaquone-proguanil regimens. Transgenic PbPfHRP2 parasites in BALB/c mice produced and exported tgPfHRP2 to the RBC cytosol similar to P. falciparum. As in humans, tgPfHRP2 levels were found to be approximately 20-fold higher within the RBC fraction than the plasma post-treatment. RBC localized tgPfHRP2 persisted longer than tgPfHRP2 in the plasma after curative treatment. tgPfHRP2 positive, but DNA negative once-infected RBCs were also detected in mouse peripheral blood for 7-9 days after curative treatment. CONCLUSIONS: The data suggest that persistence of PfHRP2 is due to slower clearance of protein from the RBC fraction of the whole blood. This appears to be a result of the presence PfHRP2 in previously infected, pitted cells, as opposed to PfHRP2 binding naïve RBCs in circulation post-treatment. The results thus confirm that the extended duration of RDT positivity after parasite clearance is likely due to pitted, once-infected RBCs that remain positive for PfHRP2.

The impact on malaria of biannual treatment with azithromycin in children age less than 5 years: a prospective study.

BACKGROUND: The MORDOR study, a cluster randomized clinical trial, showed that single-dose azithromycin (20 mg/kg) administered biannually for 2 years to preschool children reduced mortality; a study was conducted to determine its effect on clinical symptomatic episodes of malaria as a potential mechanism for mortality benefit. METHODS: A randomized control trial (RCT) was conducted, whereby 30 randomly selected communities in Kilosa District, Tanzania were randomized to receive 6-monthly treatment of children ages 1-59 months with single-dose azithromycin (20 mg/kg) vs. placebo. A prospective cohort study was nested within the RCT: children, aged 1 to 35 months at baseline, were randomly selected in each community and evaluated at 6-monthly intervals for 2 years. At each visit, the children were assessed for recent or ongoing fever and anti-malarial treatment; a rapid diagnostic test (RDT) for malaria was performed. The two major outcomes of interest were prevalence of RDT positivity and clinical malaria. The latter was defined as RDT-positivity with fever at time of evaluation and/or reported fever in the 3 days prior to evaluation. Methods that account for correlations at community level and within individuals over time were used to evaluate associations. RESULTS: At baseline, the prevalence rates in the children in the azithromycin and placebo arms were 17.6% vs. 15.5% for RDT positivity (p = 0.76) and 6.1% vs. 4.3% (p = 0.56) for clinical malaria. There was a decline in both RDT-positivity and clinical malaria over time in both arms. The difference by treatment assignment was not significant for clinical malaria; it was significant for RDT-positivity with greater odds of decline in the placebo arm (p = 0.01). CONCLUSIONS: Lack of evidence for a significant difference in the prevalence of clinical malaria in children at any visit following treatment suggests that the effect of single-dose azithromycin on malaria is at best transient and limited in scope. Chance overrepresentation of non-seasonal transmission in the communities in the azithromycin arm may account for higher rates of RDT-positivity and less decline over time. Trial registration Clinicaltrials.gov NCT02047981.

Superior Pyronaridine Single-Dose Pharmacodynamics Compared to Artesunate, Chloroquine, and Amodiaquine in a Murine Malaria Luciferase Model.

Many previous in vitro and in vivo preclinical malaria drug studies have relied on low-parasite-number drug inhibition numerically compared to the untreated controls. In contrast, human malaria drug studies measure the high-parasite-density killing near 100 million/ml. Here we compared the in vivo single-dose pharmacodynamic properties of artesunate and the 4-aminoquinolines pyronaridine, chloroquine, and amodiaquine in a Plasmodium berghei ANKA-green fluorescent protein GFP-luciferase-based murine malaria blood-stage model. Pyronaridine exhibited dose-dependent killing, achieving parasite reductions near 5 to 6 logs at 48 h, with complete cure at 10 mg/kg of body weight compared to artesunate, which exhibited a 48-h dose-dependent killing with a 2-log drop at the noncurative 250-mg/kg dose. Chloroquine, which was noncurative, and amodiaquine, which was partially curative, had nearly the same initial dose-independent killing, with a lag phase of minimal parasite reduction at all doses between 6 and 24 h, followed by a 2.5-log reduction at 48 h. In experiments with drug-treated, washed infected blood transfer to naive mice, chloroquine and amodiaquine showed fewer viable parasites at the 24-h transfer than at the 8-h transfer, measured by a prolonged return to parasitemia, despite a similar parasite log reduction at these time points, in contrast to the correlation of the parasite log reduction to viable parasites with artesunate and pyronaridine. Artesunate in combination with pyronaridine exhibited an initial parasite reduction similar to that achieved with pyronaridine, while with chloroquine or amodiaquine, the reduction was similar to that achieved with artesunate. Single-oral-dose pyronaridine was much more potent in vivo than artesunate, chloroquine, and amodiaquine during the initial decline in parasites and cure.