scholarly journals 1000. Serotype 3 pneumococci evade activation of the classical complement pathway

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S591-S591
Author(s):  
Rotem Lapidot ◽  
Mario Ramirez ◽  
Dayeun Lee ◽  
Ingrid L Scully ◽  
Bradford D Gessner ◽  
...  

Abstract Background Complement classical pathway (CCP) activation is the major mechanism leading to opsonophagocytic pneumococcal killing. Following immunization with 13-valent pneumococcal conjugate vaccine (PCV13), opsonophagocytic titers are lowest against serotype 3 among the 13 vaccine serotypes. Post licensure surveillance indicated early declines in serotype 3 invasive pneumococcal disease (IPD) were not sustained over time Methods Using flow cytometry, we measured C3 and C4 deposition on serotype 3 strains from children with IPD or nasopharyngeal [NP] carriage, and analyzed by clade. C4 deposition is an indicator of CCP, while C3 deposition is common to all complement pathways. We measured C3/C4 deposition on serotype 3 pneumococcal strains incubated with antibody depleted complement alone or with complement and the following antibodies: mouse monoclonal anti-capsular IgG or IgM, rabbit polyclonal serotype 3 antisera (IgG + IgM) [RPS3A] and RPS3A combined with anti-rabbit IgM, which blocks IgM function, leaving only polyclonal IgG Results Serotype 3 strains demonstrated high variability in C3 binding when incubated with complement alone. RPS3A (containing both IgM+IgG) and monoclonal IgM activated CCP in all strains. Anti- serotype 3 monoclonal IgG and polyclonal IgG demonstrated absent or limited CCP activation; but activated alternative pathway in some strains. When analyzing complement deposition by clade, a lower proportion of clade II NP serotype 3 strains bound C3 when incubated with complement or monoclonal IgG, compared to clade Ia NP strains. Differences between clade Ia and II IPD strains were not apparent. Conclusion Serotype 3 strains did not demonstrate activation of the CCP in the presence IgG and varied in C3 deposition. Pneumococcal strains that evade CCP activation may be less sensitive to opsonophagocytosis. Our findings suggest a mechanism by which serotype 3 carriage and disease may persist despite immunization with conjugate vaccine containing serotype 3 polysaccharide. Disclosures Rotem Lapidot, MD MSCI, Pfizer (Consultant, Grant/Research Support, Advisor or Review Panel member) Mario Ramirez, PhD, GlaxoSmithKline (Advisor or Review Panel member)Merck Sharp & Dohme (Advisor or Review Panel member)Pfizer (Speaker’s Bureau) Ingrid L. Scully, PhD, Pfizer (Employee, Shareholder) Bradford D. Gessner, MD, MPH, Pfizer Inc. (Employee) stephen pelton, MD, Merck Vaccines (Advisor or Review Panel member, Research Grant or Support)Pfizer, Inc. (Consultant, Advisor or Review Panel member, Research Grant or Support)Sanofi pasteur (Advisor or Review Panel member, Research Grant or Support, DSMB)Seqirus (Consultant)

2001 ◽  
Vol 194 (6) ◽  
pp. 747-756 ◽  
Author(s):  
Anthony P. Manderson ◽  
Matthew C. Pickering ◽  
Marina Botto ◽  
Mark J. Walport ◽  
Christopher R. Parish

There is evidence that the classical complement pathway may be activated via a “C1-tickover” mechanism, analogous to the C3-tickover of the alternative pathway. We have quantitated and characterized this pathway of complement activation. Analysis of freshly collected mouse and human plasma revealed that spontaneous C3 activation rapidly occurred with the generation of C3 fragments in the plasma. By the use of complement- and Ig-deficient mice it was found that C1q, C4, C2, and plasma Ig were all required for this spontaneous C3 activation, with the alternative complement pathway further amplifying C3 fragment generation. Study of plasma from a human with C1q deficiency before and after therapeutic C1q infusion confirmed the existence of a similar pathway for complement activation in humans. Elevated levels of plasma C3 were detected in mice deficient in complement components required for activation of either the classical or alternative complement pathways, supporting the hypothesis that there is continuous complement activation and C3 consumption through both these pathways in vivo. Blood stasis was found to stimulate C3 activation by classical pathway tick-over. This antigen-independent mechanism for classical pathway activation may augment activation of the complement system at sites of inflammation and infarction.


2008 ◽  
Vol 76 (8) ◽  
pp. 3761-3770 ◽  
Author(s):  
Jose Yuste ◽  
Ashwin Sen ◽  
Lennart Truedsson ◽  
Göran Jönsson ◽  
Liang-Seah Tay ◽  
...  

ABSTRACT Results from studies using mice deficient in specific complement factors and clinical data on patients with an inherited deficiency of the classical complement pathway component C2 suggest that the classical pathway is vital for immunity to Streptococcus pneumoniae. However, the consequences of defects in classical pathway activity for opsonization with C3b and the phagocytosis of different S. pneumoniae serotypes in human serum are not known, and there has not been a systematic analysis of the abilities of sera from subjects with a C2 deficiency to opsonize S. pneumoniae. Hence, to investigate the role of the classical pathway in immunity to S. pneumoniae in more detail, flow cytometry assays of opsonization with C3b and the phagocytosis of three capsular serotypes of S. pneumoniae were performed using human sera depleted of the complement factor C1q or B or sera obtained from C2-deficient subjects. The results demonstrate that, in human serum, the classical pathway is vital for C3b-iC3b deposition onto cells of all three serotypes of S. pneumoniae and seems to be more important than the alternative pathway for phagocytosis. Compared to the results for sera from normal subjects, C3b-iC3b deposition and total anti-S. pneumoniae antibody activity levels in sera obtained from C2−/− subjects were reduced and the efficiency of phagocytosis of all three S. pneumoniae strains was impaired. Anticapsular antibody levels did not correlate with phagocytosis or C3b-iC3b deposition. These data confirm that the classical pathway is vital for complement-mediated phagocytosis of S. pneumoniae and demonstrate why subjects with a C2 deficiency have a marked increase in susceptibility to S. pneumoniae infections.


1998 ◽  
Vol 66 (12) ◽  
pp. 6027-6029 ◽  
Author(s):  
Mason X. Zhang ◽  
Jim E. Cutler ◽  
Yongmoon Han ◽  
Thomas R. Kozel

ABSTRACT Polyclonal antimannan immunoglobulin G (IgG) activates the classical complement pathway and accelerates initiation of the alternative pathway by Canidida albicans. This dual role was assessed for two antimannan IgM monoclonal antibodies (MAbs). MAb B6.1 is specific for an epitope on the acid-labile portion of C. albicans phosphomannan; MAb B6 is specific for an epitope on the acid-stable region. Both MAbs were potent activators of the classical pathway but poor facilitators of alternative pathway initiation.


2007 ◽  
Vol 75 (8) ◽  
pp. 4071-4081 ◽  
Author(s):  
Sanjay Ram ◽  
Jutamas Ngampasutadol ◽  
Andrew D. Cox ◽  
Anna M. Blom ◽  
Lisa A. Lewis ◽  
...  

ABSTRACT Lipooligosaccharide (LOS) heptose (Hep) glycan substitutions influence gonococcal serum resistance. Several gonococcal strains bind the classical complement pathway inhibitor, C4b-binding protein (C4BP), via their porin (Por) molecule to escape complement-dependent killing by normal human serum (NHS). We show that the proximal glucose (Glc) on HepI is required for C4BP binding to Por1B-bearing gonococcal strains MS11 and 1291 but not to FA19 (Por1A). The presence of only the proximal Glc on HepI (lgtE mutant) permitted maximal C4BP binding to MS11 but not to 1291. Replacing 1291 lgtE Por with MS11 Por increased C4BP binding to levels that paralleled MS11 lgtE, suggesting that replacement of the Por1B molecule dictated the effects of HepI glycans on C4BP binding. The remainder of the strain background did not affect C4BP binding; replacing the Por of strain F62 with MS11 Por (F62 PorMS11) and truncating HepI mirrored the findings in the MS11 background. C4BP binding correlated with resistance to killing by NHS in most instances. F62 PorMS11 and its lgtE mutant were sensitive to NHS despite binding C4BP, secondary to kinetically overwhelming classical pathway activation and possibly increased alternative pathway activation (measured by factor Bb binding) by the F62 background. FA19 lgtF (HepI unsubstituted) resisted killing by only 10% NHS, not 50% NHS, despite binding levels of C4BP similar to those of FA19 and FA19 lgtE (both resistant to 50% serum), suggesting a role for the proximal Glc in serum resistance independently of C4BP binding. This study provides mechanistic insights into how HepI LOS substitutions affect the serum resistance of N. gonorrhoeae.


2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S582-S583
Author(s):  
Eleni Karantoni ◽  
Yiqi Su ◽  
Anat Stern ◽  
Phaedon D Zavras ◽  
Sergio Giralt ◽  
...  

Abstract Background The epidemiology of CMV end-organ disease (EOD) after Hematopoietic Cell Transplant (HCT) in the era of preemptive therapy (PET) is defined. In contrast, less data exists on refractory and/or resistant (R/R) CMV. We report on 1) the incidence; 2) risk factors and outcomes of R/R CMV by 1-year post HCT. Methods Retrospective review of 167 CMV seropositive (R+) recipients of first marrow or peripheral blood HCT from 1/2014 - 12/2017 managed by PET. Refractory CMV was defined as failure to achieve >1 log10 decrease in CMV viral load (VL) and having VL >1,000 IU/mL after ≥14 day of PET. Resistant CMV required genotypic confirmation of resistance mutation(s) in UL54 and/or UL97 genes. End organ disease (EOD) was defined by standard criteria. Patients (pts) were followed through 1-year post HCT and were categorized in two mutually exclusive groups as R/R and no R/R. Demographics, clinical characteristics and outcomes were extracted from medical records and hospital databases. Univariable and multivariable logistic models were used to identify risk factors for R/R CMV. Results Of 167 PET recipients, 91 (54.5%) received ex vivo T cell depleted (TCD) HCT; 40 (24.0%) had mismatched donor; and 26 (15.6%) had multiple myeloma. 66/167 (39.5%) pts developed refractory CMV (6 pts also had resistant CMV). Time from HCT to CMV viremia was shorter in R/R group: median (IQR) 21.5 (17.2-27.8) days compared to no R/R group: 26 (19-32) days (p=0.031). Maximum VL was higher for R/R compared to no R/R: median (IQR) 9,118 (2,849-18,456) and 868 (474-1,908), respectively (p< 0.001). In multivariable model, risk factors for R/R included TCD HCT (p< 0.0001) and higher VL at PET initiation (p=0.0002). In contrast, CMV seropositive donor (p=0.035) was protective (Figure 1). CMV EOD developed in 28.2% of R/R and 16.2% of no R/R groups (p=0.085) (Figure 2). Overall survival at 1 year was 59.1% for R/R compared to 83.1% for no R/R group (p=0.00027) (Figure 3). Figure 1. Adjusted odds ratio (OR) and 95% confidence interval (CI) from multivariable model evaluating risk factors of refractory/resistant (R/R) CMV. Figure 2. Cumulative incidence curves of CMV end-organ disease (EOD) at 1-year post HCT Figure 3. Kaplan-Meier survival curves of overall survival (OS) at 1-year post HCT Conclusion 1) Refractory and/or resistant CMV occurred in 39,5% of PET recipients. 2) T-cell depletion and higher CMV VL at PET initiation were risk factors for R/R CMV in multivariable models. 3) R/R CMV was associated with more EOD and worse overall survival. Disclosures Sergio Giralt, MD, Amgen (Advisor or Review Panel member, Research Grant or Support, Served an advisory board for Amgen, Actinuum, Celgene, Johnson & Johnson, JAZZ pharmaceutical, Takeda, Novartis, KITE, and Spectrum pharma and has received research support from Amgen, Actinuum, Celgene, Johnson & Johnson, and Miltenyi, Takeda.) Miguel-Angel Perales, MD, Abbvie (Other Financial or Material Support, Honoraria from Abbvie, Bellicum, Celgene, Bristol-Myers Squibb, Incyte, Merck, Novartis, Nektar Therapeutics, Omeros, and Takeda.)ASTCT (Other Financial or Material Support, Volunteer member of the Board of Directors of American Society for Transplantation and Cellular Therapy (ASTCT), Be The Match (National Marrow Donor Program, NMDP), and the CIBMTR Cellular Immunotherapy Data Resource (CIDR) Committee)Cidara Therapeutics (Advisor or Review Panel member, Other Financial or Material Support, Serve on DSMBs for Cidara Therapeutics, Servier and Medigene, and the scientific advisory boards of MolMed and NexImmune.)Kite/Gilead (Research Grant or Support, Other Financial or Material Support, Received research support for clinical trials from Incyte, Kite/Gilead and Miltenyi Biotec.) Genovefa Papanicolaou, MD, Chimerix (Research Grant or Support)Merck&Co (Research Grant or Support, Investigator and received funding and consulting fees from Merck, Chimerix, Shire and Astellas)


2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S739-S739
Author(s):  
Allison McGeer

Abstract Background Herd immunity from pediatric pneumococcal conjugate vaccine (PCV) programs has resulted in substantial reductions in IPD due to PCV serotypes (ST). We assessed whether similar changes in ST distribution occur in non-bacteremic pneumococcal pneumonia (NBPP). Methods The Toronto Invasive Bacterial Diseases Network performs population-based surveillance for IPD and hospitalized, culture-confirmed NBPP in Toronto/Peel Region, Canada (Pop 4.5M). Patient data are collected by interview/chart review; illness associated with respiratory isolates is categorized using Musher criteria. Results Since 2002, 6627 episodes of IPD, and 7323 non-bacteremic episodes with a respiratory isolate of S. pneumoniae (2180 meeting modified Musher criteria for NBPP) have occurred in adults. Distributions of vaccine-type serotypes in IPD and NBPP pre-PCV7 (2002-2004), post-PCV7 (2006-2009) and late post-PCV13 (2014-2019) are shown in the Figure. There were no significant changes in distribution of vaccine serotype groups from 2014-2019 in IPD or NBPP. From 2014-2019, serotypes included in PCV13 and PCV20 were associated with 33% and 59% of IPD cases, and 29% and 49% of NBPP cases in adults.. Figure. distribution of serotype groups included in different pneumococcal vaccines in cases of IPD and non-bacteremic pneumonia Conclusion Eight years post routine infant PCV13 implementation, PCV13 type IPD and NBPP persists in adults. The distribution of vaccine-type strains is similar in IPD and NBPP; although non-vaccine-type strains are more common in NBPP. Disclosures Allison McGeer, MD, FRCPC, GlaxoSmithKline (Advisor or Review Panel member, Research Grant or Support)Merck (Advisor or Review Panel member, Research Grant or Support)Pfizer (Research Grant or Support)


2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S183-S183
Author(s):  
Rajesh Gandhi ◽  
Joshua Cyktor ◽  
Ronald Bosch ◽  
Hanna Mar ◽  
Gregory Laird ◽  
...  

Abstract Background HIV-1 proviruses persist in people on antiretroviral therapy (ART) but most are defective and do not constitute a replication-competent reservoir. The decay of infected cells carrying intact compared with defective HIV-1 proviruses has not been well-defined in people on ART. Methods We separately quantified intact and defective proviruses (using an intact proviral DNA assay), residual plasma viremia, and markers of inflammation and activation in people on long-term ART. Longitudinal measurements were done at three timepoints: timepoint 1 was a median of 7.1 years on ART; timepoint 2 was a median of 3.7 years later; timepoint 3 was a median of 5.5 years after timepoint 1 and a median 12 years after starting ART (Figure 1). Figure 1: Study timepoints Results Among 40 participants tested longitudinally from a median of 7.1 years to 12 years after ART initiation, intact provirus levels declined significantly over time (median half-life 7.1 years; 95% confidence interval [CI], 3.9, 18), whereas defective provirus levels did not decrease. The median half-life of total HIV-1 DNA was 41.6 years (95% CI, 13.6, 75). When we evaluated the change in proviral DNA per year, intact proviral DNA declined significantly more (p< 0.001) than defective proviral DNA (the latter did not change) (Figure 2). The proportion of all proviruses that were intact diminished over time on ART, from about 10% at the first on-ART timepoint to about 5% at the last timepoint (Figure 3). At timepoint 1, intact provirus levels on ART correlated with total HIV-1 DNA and residual plasma viremia, but there was no evidence for associations between intact provirus levels and inflammation or immune activation. Figure 2: Percent change in HIV-1 proviral DNA per year Figure 3: Total HIV-1 proviruses (grey bars) and the percentage of intact proviruses (red lines, displaying median, Q1, Q3) by timepoint. Conclusion Cells containing intact, replication-competent proviruses are selectively lost during suppressive ART. Defining the mechanisms involved should inform strategies to accelerate HIV-1 reservoir depletion. Disclosures Rajesh Gandhi, MD, Merck (Advisor or Review Panel member) Gregory Laird, PhD, Accelevir Diagnostics (Shareholder, Other Financial or Material Support, Employee) Albine Martin, PhD, Accelevir Diagnostics (Shareholder, Other Financial or Material Support, Employee) Bernard Macatangay, MD, Gilead (Grant/Research Support) Joseph J. Eron, MD, Gilead Sciences (Consultant, Research Grant or Support)Janssen (Consultant, Research Grant or Support)Merck (Consultant)ViiV Healthcare (Consultant, Research Grant or Support) Janet Siliciano, PhD, Gilead (Advisor or Review Panel member)US Military HIV Research Program (Advisor or Review Panel member) John Mellors, MD, Abound Bio (Shareholder)Accelevir Diagnostics (Consultant)Co-Crystal Pharmaceuticals (Shareholder)Gilead (Consultant, Grant/Research Support)Merck (Consultant)


2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S52-S52
Author(s):  
Pegah Shakeraneh ◽  
Jeffrey Steele ◽  
Robert Seabury ◽  
Stephen J Thomas ◽  
Kristopher M Paolino ◽  
...  

Abstract Background Ceftriaxone and azithromycin are common empiric antibiotics for community-acquired pneumonia (CAP). Despite low suspicion for atypical infection, azithromycin is often continued for a full course. Negative laboratory data for atypical bacteria may assist with azithromycin de-escalation. Thus, a pharmacist-driven azithromycin de-escalation protocol was implemented for immunocompetent, non-intensive care unit (ICU) patients treated for CAP. The primary outcome was to compare azithromycin duration before and after protocol implementation. Secondary outcomes included hospital length of stay (LOS) and all-cause 30-day readmission. Methods This was a single-center, quasi-experimental study of hospitalized, non-ICU patients treated with azithromycin and a beta-lactam for CAP. The pre- and post-intervention cohorts were from 07/01/2018–04/30/2019 and 07/01/2019–04/30/2020, respectively. Patients were included if they were ≥18 years old, diagnosed with CAP, and had a negative Legionella pneumophila urinary antigen and negative nasopharyngeal swab PCR for Mycoplasma pneumoniae and Chlamydia pneumoniae. Patients were excluded if they were immunocompromised, admitted to an ICU, prescribed azithromycin for an alternative indication, or had evidence of atypical bacteria. Results After exclusion criteria were applied, 90 and 100 patients were included in the pre- and post-intervention cohorts, respectively. Demographic and clinical characteristics were mostly similar between cohorts. This initiative was associated with a statistically significant decrease in azithromycin duration (2 days (IQR 1–2.75) vs. 5 days (IQR 3–6), p < 0.001) and hospital LOS (3 days (IQR 2–5) vs. 5 days (IQR 3–8.25), p < 0.001). No statistically significant difference was observed for all-cause 30-day readmission (14 days (15.6%) vs 13 days (13.0%), p=0.614). Conclusion Implementation of a pharmacist-driven azithromycin de-escalation protocol for CAP was associated with reduced azithromycin duration and hospital LOS, but not all-cause 30-day readmission. Disclosures Jeffrey Steele, PharMD, Paratek Pharmaceuticals (Advisor or Review Panel member) Wesley D. Kufel, PharmD, Melinta (Research Grant or Support)Merck (Research Grant or Support)Theratechnologies, Inc. (Advisor or Review Panel member)


2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S72-S72
Author(s):  
Peter G Pappas ◽  
Andrej Spec ◽  
Marisa Miceli ◽  
Gerald McGwin ◽  
Rachel McMullen ◽  
...  

Abstract Background C-itra is the drug of choice for treatment of most non-CNS, non-life-threatening forms of endemic mycoses (EM), including histoplasmosis, blastomycosis, coccidioidomycosis, sporotrichosis and talaromycosis. SUBA represents a new formulation of itraconazole that utilizes nanotechnology to improve bioavailability when administered orally. SUBA is formulated as nanoparticles allowing for absorption in the small bowel while not relying on gastric acidity for optimal absorption. MSG-15 is an open-label, comparative clinical trial comparing SUBA to c-itra for the treatment of EM. Herein we report the final PK and AE profiles of these two compounds. Methods Subjects with proven and probable EM were eligible this open-label comparative study. The protocol allowed up to 14 d of prior therapy with any antifungal for this episode of EM. Subjects were randomized to receive either SUBA 130 mg po bid or c-itra 200 mg po bid for up to 6 months. Follow up occurred at 7, 14, 28, 42, 84 and 180 d post-enrollment. PK samples were obtained at 7, 14, and 42 d. Clinical assessment, including symptom assessment, AEs, overall drug tolerance, and quality of life were assessed at each visit. We used descriptive statistics for this analysis. Results 89 subjects with EM entered the trial, including 43 on SUBA and 46 on c-itra. We measured PK serum levels of itra and hydroxyl-itra at days 7, 14, and 42 and these data are depicted in Figures 1-3. There were no significant differences in these levels, including combined itra/hydroxyl-itra levels, among the two study arms. AUC for itra and hydroxyl-itra were similar for both arms. AEs as assessed at each study evaluation were also quite similar among the two study arms. Overall, any AE occurred in 74% vs 85% of SUBA and c-itra recipients, respectively (NS). Drug-related AEs occurred in 35% vs 41% of SUBA and itra recipients, respectively (NS). Most common drug-related AEs included cardiovascular (edema and hypertension), nausea and loss of appetite. Combined Itraconazole and Hydroxy-itraconazole Concentration Over Time Conclusion Compared to c-itra, SUBA demonstrates almost identical serum levels despite being dosed at roughly 60% standard dosing for c-itra (130 mg po bid vs 200 mg po bid). SUBA is slightly better tolerated than c-itra, although the specific AEs are similar. Disclosures Peter G. Pappas, MD, Astellas (Research Grant or Support)Cidara (Research Grant or Support)F2G (Consultant)Matinas (Consultant, Scientific Research Study Investigator)Mayne Pharma (Research Grant or Support)Scynexis (Research Grant or Support) Andrej Spec, MD, MSCI, Mayne Pharma (Grant/Research Support) Marisa Miceli, MD, SCYNEXIS, Inc. (Advisor or Review Panel member) George R. R. Thompson III, III, MD, Amplyx (Consultant, Grant/Research Support)Appili (Consultant)Astellas (Consultant, Grant/Research Support)Avir (Grant/Research Support)Cidara (Consultant, Grant/Research Support)F2G (Consultant, Grant/Research Support)Mayne (Consultant, Grant/Research Support)Merck (Scientific Research Study Investigator)Pfizer (Advisor or Review Panel member)


2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S340-S340
Author(s):  
Antonella Castagna ◽  
David Shu Cheong Hui ◽  
Kathleen M Mullane ◽  
Kathleen M Mullane ◽  
Mamta Jain ◽  
...  

Abstract Background Remdesivir (RDV) has been shown to shorten recovery time and was well tolerated in patients with severe COVID-19. Here we report baseline characteristics associated with clinical improvement at day (d) 14. Methods We enrolled hospitalized patients with confirmed SARS-CoV-2 infection, oxygen saturation >94% on room air, and radiological evidence of pneumonia. Patients were randomized 1:1:1 to receive 5d or 10d of intravenous RDV once daily plus standard of care (SoC), or SoC only. For this analysis, patients were followed through discharge, d14, or death. Baseline demographic and disease characteristics associated with clinical improvement in oxygen support (≥2-point improvement on a 7-category ordinal scale ranging from discharge to death) were evaluated using multivariable logistic regression methods. Results 584 patients were randomized and treated (5/10d RDV, n=384; SoC: n=200). 159 (27%) were ≥65y, 227 (39%) female, 328 (61%) white, 102 (19%) Asian, and 99 (19%) Black. 252 participants (43%) were enrolled in Europe, 260 (45%) North America (NA), and 72 (12%) in Asia. Most patients (483 [83%]) were not on supplemental oxygen but required medical care at baseline. In a multivariable model, 5/10d RDV was significantly positively associated with clinical improvement (adjusted odds ratio [OR] 1.69, 95% CI: 1.08, 2.65; p=0.0226). Significant covariables positively associated with clinical improvement included age < 65y (p< 0.0001) and region of treatment (Europe and NA vs Asia, p< 0.0001 each; Table); other examined factors were not significantly associated with clinical improvement, including gender, race, ethnicity, baseline oxygen support, duration of symptoms and hospitalization, obesity, and baseline transaminase levels. Table 1. Conclusion In moderate COVID-19 patients, after adjusting for treatment arm, age < 65y and region (NA vs Asia; Europe vs Asia) were associated with higher rates of clinical improvement. These observations recapitulate younger age as positive prognostic factor, and highlight the differences in the impact of the pandemic globally. Disclosures Antonella Castagna, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) David Shu Cheong Hui, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) Kathleen M. Mullane, DO, PharmD, Gilead Sciences Inc. (Grant/Research Support, Scientific Research Study Investigator) Mamta Jain, MD, Gilead Sciences Inc. (Scientific Research Study Investigator, Research Grant or Support)GlaxoSmithKline (Advisor or Review Panel member)Janssen (Research Grant or Support)Merck (Research Grant or Support) Massimo Galli, MD, Gilead Sciences Inc. (Grant/Research Support, Scientific Research Study Investigator, Advisor or Review Panel member, Other Financial or Material Support, Personal fees) Shan-Chwen Chang, MD, PhD, Gilead Sciences Inc. (Scientific Research Study Investigator) Robert H. Hyland, MD, Gilead Sciences Inc. (Employee, Shareholder) Devi SenGupta, MD, Gilead Sciences Inc. (Employee, Shareholder) Huyen Cao, MD, Gilead Sciences Inc. (Employee, Shareholder) Hailin Huang, PhD, Gilead Sciences Inc. (Employee, Shareholder) Anand Chokkalingam, PhD, Gilead Sciences (Employee) Anu Osinusi, MD, Gilead Sciences (Employee) Diana M. Brainard, MD, Gilead Sciences (Employee) Christoph Lübbert, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) David Chien Boon Lye, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) David Chien Boon Lye, MD, NO DISCLOSURE DATA Judith A. Aberg, MD, Theratechnology (Consultant) Enrique Navas Elorza, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) Karen T. Tashima, MD, Bristol-Myers Squibb (Research Grant or Support)Gilead Sciences Inc. (Grant/Research Support, Scientific Research Study Investigator)GlaxoSmithKline (Research Grant or Support)Merck (Research Grant or Support)Tibotec (Research Grant or Support)Viiv Healthcare (Research Grant or Support) Mark McPhail, MD, Gilead Sciences Inc. (Scientific Research Study Investigator)


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