Convalescent Levels Research Articles

2623. Persistence of SARS-CoV-2 S IgG Antibodies in Children that suffered from COVID-19 and Association of Antibody Levels with Vaccination Status

Abstract Background Serum levels of IgG antibodies against SARS-CoV-2 spike protein (S) in children who suffered COVID-19 have been found to last between 4 to 12 months. We aimed to characterize the antibody response against SARS-CoV-2 after 1 year of COVID-19 in unvaccinated and vaccinated children. Methods A cohort study included unvaccinated and vaccinated children (< 18 years) with a previous SARS-CoV-2 infection. Blood samples were collected during the acute phase, in convalescence and 1 year after suffering the disease. For comparative purposes, vaccinated adult relatives who suffered COVID-19 in the same period were included. SARS-CoV-2 S IgG serum levels were determined by immunoassay. Neutralizing activity was determined by the decrease of GFP expression in SARS-CoV-2 S-pseudotyped lentivirus infected HEK-293T cells. Results Eighty-four children were included, median age 8 years (IQR 2-12), 54% (n=45) were females; 38% (n=32) were vaccinated. Also, 50 adults were studied, median age 35 years (IQR 29-44), 76% (n=38) were females. SARS-CoV-2 S IgG levels 1 year after COVID-19 decreased 2.2- to 10.8- fold compared to convalescent levels in unvaccinated children. SARS-CoV-2 S IgG titers positively correlated with neutralizing antibody titers in convalescence and 1 year after COVID-19 (p< 0.05). SARS-CoV-2 S IgG levels were significantly higher in children with incomplete (p=0.0088) and complete/booster (p< 0.0001) vaccination as compared to unvaccinated children. Children that received mRNA vaccines showed higher SARS-CoV-2 IgG titers than children that received an inactivated vaccine (p< 0.0001). SARS-CoV-2 S IgG titers positively correlated with age in vaccinated children (rS=0.4303, p=0.014). SARS-CoV-2 IgG titers 1 year after COVID-19 did not associate with disease severity or the presence of comorbidities. No significant differences in SARS-CoV-2 S IgG levels were found between vaccinated children and adults, at the same vaccination level. Conclusion These findings highlight the importance of child vaccination to maintain a long-term humoral immune response against SARS-CoV-2 despite having been infected. Also, mRNA vaccines elicited a higher antibody response than inactivated vaccines against SARS-CoV-2 in children. Disclosures All Authors: No reported disclosures

Differences in mRNA-1273 (Moderna) and BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 vaccine immunogenicity among patients undergoing dialysis.

Background:Differences in immunogenicity between mRNA SARS-CoV-2 vaccines have not been well characterized in patients undergoing dialysis. We compared the serologic response in patients undergoing maintenance hemodialysis after vaccination against SARS-CoV-2 with BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna).Methods:We conducted a prospective observational cohort study at 2 academic centres in Toronto, Canada, from Feb. 2, 2021, to July 20, 2021, which included 129 and 95 patients who received the BNT162b2 and mRNA-1273 SARS-CoV-2 vaccines, respectively. We measured SARS-CoV-2 immunoglobulin G antibodies to the spike protein (anti-spike), receptor binding domain (anti-RBD) and nucleocapsid protein (anti-NP) at 6–7 and 12 weeks after the second dose of vaccine and compared those levels with the median convalescent serum antibody levels from 211 controls who were previously infected with SARS-CoV-2.Results:At 6–7 weeks after 2-dose vaccination, we found that 51 of 70 patients (73%) who received BNT162b2 and 83 of 87 (95%) who received mRNA-1273 attained convalescent levels of anti-spike antibody (p < 0.001). In those who received BNT162b2, 35 of 70 (50%) reached the convalescent level for anti-RBD compared with 69 of 87 (79%) who received mRNA-1273 (p < 0.001). At 12 weeks after the second dose, anti-spike and anti-RBD levels were significantly lower in patients who received BNT162b2 than in those who received mRNA-1273. For anti-spike, 70 of 122 patients (57.4%) who received BNT162b2 maintained the convalescent level versus 68 of 71 (96%) of those who received mRNA-1273 (p < 0.001). For anti-RBD, 47 of 122 patients (38.5%) who received BNT162b2 maintained the anti-RBD convalescent level versus 45 of 71 (63%) of those who received mRNA-1273 (p = 0.002).Interpretation:In patients undergoing hemodialysis, mRNA-1273 elicited a stronger humoral response than BNT162b2. Given the rapid decline in immunogenicity at 12 weeks in patients who received BNT162b2, a third dose is recommended in patients undergoing dialysis as a primary series, similar to recommendations for other vulnerable populations.

Evolution of cytokines/chemokines in cases with community-acquired pneumonia and distinct etiologies.

To compare the systemic cytokines/chemokines levels over time during the evolution of children hospitalized with community-acquired pneumonia (CAP) with and without pneumococcal infection. Children less than 5-years-old hospitalized with CAP were prospectively investigated in Salvador, Brazil. Clinical data and biological samples were collected to investigate 20 etiological agents and to determine serum cytokines/chemokines levels on admission and 2 to 4 weeks later. Cases with pneumococcal infection received this diagnosis irrespective of also having other etiologies. A total of 277 patients were enrolled, however, serum sample was unavailable for cytokine measurement upon admission (n = 61) or upon follow-up visit (n = 36), etiology was undetected (n = 50) and one patient did not attend the follow-up visit. Therefore, this study group comprised of 129 cases with established etiology. The median (interquartile range) age and sampling interval was 18 (9-27) months and 18 (16-21) days, respectively. Established etiology was viral (52.0%), viral-bacterial (30.2%), and bacterial (17.8%). Pneumococcal infection was found in 31 (24.0%) patients. Overall, median interleukin-6 (IL-6; 10.6 [4.7-30.6] vs 21.0 [20.2-21.7]; P = .03), IL-10 (3.5 [3.1-4.5] vs 20.1 [19.8-20.4]; P < .001), and CCL2 (19.3 [12.4-23.2] vs 94.0 [67.2-117.8]; P < .001) were significantly higher in convalescent serum samples, whereas median CXCL10 (83.6 [36.4-182.9] vs 14.6 [0-116.6]; P < .001) was lower. Acute vs convalescent levels evolution of IL-10, CCL2, and CXCL10 did not differ among patients with or without pneumococcal infection. However, IL-6 decreased (27.8 [12.3-48.6] vs 20.8 [20.2-22.6]; P = .1) in patients with pneumococcal infection and increased (9.0 [4.2-22.6] vs 21.0 [20.2-21.7]; P = .001) in patients without it. The marked increase of IL-6 serum levels during the acute phase makes it a potential biomarker of pneumococcal infection among children with CAP.

Brain Natriuretic Peptide, Troponin and D-Dimer Levels in Relation to Long-Term Functional Outcome after a First Episode of Pulmonary Embolism: Results from the E.L.O.P.E. Study

Background: Biomarkers such as brain natriuretic peptide (BNP), high-sensitivity cardiac troponin (hsTnT) and d-dimer (DD) are useful for acute or short-term risk stratification after pulmonary embolism (PE) to predict right ventricular dysfunction, recurrent PE or death. However, whether acute or convalescent levels of these biomarkers predict longterm functional limitation after PE has not been evaluated. To address this knowledge gap, we performed the ELOPE (Evaluation of Longterm Outcomes after PE) Study, a prospective, observational, multicenter cohort study of long-term outcomes after acute PE (www.clinicaltrials.gov NCT01174628).Objectives: To describe levels of NT-proBNP, hsTnT and d-dimer at baseline and 6 months in patients with acute PE, and to assess the relationship between biomarker levels and functional status at 1 year.Methods: Patients ³ 18 years old with a 1st episode of acute PE diagnosed within the previous 10 days screened at 5 Canadian recruiting centers were potentially eligible to participate. Exclusion criteria were subsegmental-only PE, preexisting severe cardiopulmonary comorbidity, previous proximal DVT, contraindication to CT pulmonary angiography (CTPA), life expectancy <1 year, unable to read questionnaire in English and French or to attend follow-up visits, and unable or unwilling to consent.Patients attended study visits at baseline, 1, 3, 6 and 12 months. Blood samples to assay NT-proBNP (serum), hsTnT (serum) and DD (plasma) were obtained at baseline and 6 months. NT-proBNP and hsTnT were measured using the cobas® 8000 modular analyzer (Roche Diagnostics, Laval, Quebec); cut-off for normal is <300pg/mL and <15ng/mL, respectively. DD was measured with the immune-turbidimetric STA®-Liatest® assay run on a STA® analyser (DiagnosticaStago, Asnieres, France); cut off for normal is <500ug FEU/L.The primary outcome for the ELOPE Study was maximal aerobic capacity as defined by peak oxygen uptake (VO2) as a percent of predicted maximal VO2 (VO2max) on a cardiopulmonary exercise test (CPET) performed at the 1-year visit, with <80% predicted VO2max considered abnormal, as per American Thoracic Society guidelines.For each biomarker at baseline and 6 months, we calculated median (IQR) values, % of values above the cutoff, and univariate relative risk (RR) for VO2max <80% predicted on 1-year CPET (see Table). Multivariate logistic regression analysis (multiple log-binomial regression) was done, adjusted for age and sex, to assess the relationship between NT-proBNP, hsTnT, DD and 1-year CPET result.Results: 984 patients were screened for participation; of these, 150 were eligible and 100 (67%) consented to participate. Mean (SD) age was 50 (15) years, 57% were male, 80% were outpatients, and 33% had concomitant DVT. PE was provoked in 21% and unprovoked in 79%; none were cancer-related.TableMedian biomarker values, % of values above cutoff, and univariate RR for VO2max <80% predicted on 1-year CPETVariableNT-proBNP (pg/mL)hsTroponin T (ng/L)D-Dimer (ug FEU/L)Visit DateBaseline6 monthsBaseline6 monthsBaseline6 monthsMedian (IQR)46 (21, 98)37 (21, 81)6 (3, 11)5 (3, 8)1230 (550, 2050)200 (110, 370)N (%) > cut-off*8 (10.1%)4 (5.8%)8 (10.1%)5 (7.2%)62 (78.5%)8 (11.6%)Univariate RR for VO2 max <80% predicted at 1 year1.74(0.99, 3.04)1.15(0.41, 3.18)1.34(0.66, 2.71)0.44(0.07, 2.57)1.42(0.66, 3.06)0.84(0.33, 2.14)*Cut-offs: see MethodsIn a multiple model adjusted for age and sex, baseline NT-proBNP >300 pg/mL was associated with a relative risk (RR) of 2.31 (95% CI 1.10, 4.86; p=0.027) for VO2max <80% predicted on 1-year CPET, whereas DD and hsTnT did not influence this risk.Conclusion: In a prospective cohort of patients with a first episode of PE without preexisting severe cardiopulmonary comorbidity, baseline NT-proBNP >300 pg/mL predicted a greater than 2-fold increased risk of abnormal CPET at 1 year after PE. This finding may allow early identification of PE patients at increased risk of poor longterm outcome after PE. Further analyses are in progress to assess the relationship between changes in biomarker levels from baseline to 6 months and 1-year CPET result.Funding: Canadian Institutes of Health Research (MOP-93627) DisclosuresWells:BMS/Pfizer: Research Funding; Bayer: Honoraria.

Oxidative damage in dengue fever

Oxidative stress may be important in the pathogenesis of dengue infection. Using accurate markers of oxidative damage, we assessed the extent of oxidative damage in dengue patients. The levels of hydroxyeicosatetraenoic acid products (HETEs), F 2-isoprostanes (F 2-IsoPs), and cholesterol oxidation products (COPs) were measured in 28 adult dengue patients and 28 age-matched study controls during the febrile, defervescent, and convalescent stages of infection. We compared the absolute and the percentage change in these markers in relation to key clinical parameters and inflammatory markers. The levels of total HETEs and total HETEs/arachidonate, total F 2-IsoPs/arachidonate, and COPs/cholesterol were higher during the febrile compared to the convalescent level. Total HETEs correlated positively with admission systolic blood pressure ( r = 0.52, p < 0.05), whereas an inverse relationship was found between 7β-hydroxycholesterol and systolic and diastolic blood pressure ( r = −0.61 and −0.59, respectively, p < 0.01). The urinary F 2-IsoP level was higher in urine during the febrile stage compared to the convalescent level. Despite lower total cholesterol levels during the febrile stage compared to convalescent levels, a higher percentage of cholesterol was found as COPs (7β-, 24-, and 27-hydroxycholesterol). The levels of platelet-activating factor–acetylhydrolase activity, vascular cellular adhesion molecule-1, tumor necrosis factor-α, and high-sensitivity C-reactive protein were higher during the febrile stage compared to their convalescent levels ( p < 0.01). Markers of oxidative damage are altered during the various stages of dengue infection.

The effect of Plasmodium falciparum infection on expression of monocyte surface molecules

Plasmodium falciparum infection may result in severe malaria in susceptible individuals. The pathogenesis of severe disease is probably a combination of the sequestration of infected erythrocytes and overstimulation of the immune response. Monocytes are a key source of many of the pro-inflammatory agents implicated but also are found sequestered in blood vessels. However, little is known about the monocyte phenotype in malaria disease. Flow cytometry was performed on fresh whole blood to determine surface expression of four receptors during acute severe and non-severe malaria and again during convalescence when uninfected. Three hundred and fifty-six children with P. falciparum infection were studied and were found to show increased expression of intercellular adhesion molecule-1 (ICAM-1), urokinase plasminogen activator receptor (uPAR), CD23 and chemokine receptor 5 (CCR5) (P<0.001) during acute disease compared with convalescent levels. Using multivariate analysis, it was found that large increases in expression of ICAM-1 (odds ratio (OR) 2.44, 95% CI 1.80-3.32) and uPAR (OR 3.14, 95% CI 1.93-5.09) but small increases in expression of CD23 (OR 0.82, 95% CI 0.68-0.96) were independently associated with severe malaria. These results give an insight into the cellular processes occurring in severe malaria and suggest that pathology is based on a complex repertoire of pro- and anti-inflammatory processes.

Increased nitric oxide production in acute diarrhoea is associated with abnormal gut permeability, hypokalaemia and malnutrition in tropical Australian Aboriginal children

Australian Aboriginal children hospitalized with diarrhoeal disease have severe manifestations with acidosis, hypokalaemia, osmotic diarrhoea and abnormal small bowel permeability. Nitric oxide (NO) production is increased in diarrhoeal disease, but its relationship to mucosal function and diarrhoeal complications is not known. We examined the relationship between NO production and complications of acute diarrhoea in Aboriginal and non-Aboriginal children between February 1998 and February 2000. We enrolled 318 children admitted to Royal Darwin Hospital into one of three groups: acute diarrhoea, non-diarrhoeal controls with no inflammatory illness, and non-diarrhoeal controls with inflammatory illness. Nitric oxide production was measured by urine nitrate-creatinine (NO x /Cr) excretion on a low nitrate diet. Small bowel intestinal permeability was measured by the lactulose-rhamnose (L/R) ratio on a timed blood specimen. The NO x /Cr ratios were markedly elevated in Aboriginal diarrhoeal cases (geometric mean [GM] = 1.23, 95% confidence interval [95% CI] 1.07–1.44), lowest in non-Aboriginal non-inflammatory controls (GM = 0.13, 95% CI 0.10–0.16) and intermediate in all other groups (GM = 0.35, 95% CI 0.28–0.43). Convalescent levels (day 5) in the Aboriginal diarrhoeal group (GM= 1.02, 95% CI 0.82–1.28) were slower to fall than L/R ratios. Multivariate analysis in the diarrhoeal group indicated that high NO production was associated with abnormal permeability, hypokalaemia and malnutrition, but not with the severity of diarrhoea, acidosis or osmotic diarrhoea. We concluded that increased NO production may contribute to impaired mucosal barrier function and hypokalaemia in acute gastroenteritis, which may be the cost of the known gut-protective and antimicrobial effects mediated by NO in acute intestinal inflammation.

Responsiveness of human immunodeficiency virus type 1-infected Kenyan women with or without prior pneumococcal disease to pneumococcal vaccine.

In East Africa, Streptococcus pneumoniae is a common and serious, but potentially preventable, human immunodeficiency virus type 1 (HIV-1)-associated pathogen. For 54 HIV-1-infected women, baseline levels of capsule-specific antibody to 2 of 4 pneumococcal serotypes were lower than levels in 15 seronegative women (P < .05). After immunization, specific antibody to all 4 serotypes increased in HIV-1-infected and -uninfected women (P < .05). Convalescent levels for 2 of 4 serotypes were greater in seronegative women, but the levels were not different between HIV-1-infected women with (n = 21) or without (n = 33) prior invasive pneumococcal disease. The baseline functional activity to kill S. pneumoniae type 14 was lower in HIV-1-infected than -uninfected women but also rose significantly in all groups after immunization. It is concluded that HIV-1 infection in Kenyan women is associated with decreased levels of natural antibody to selected pneumococcal capsular serotypes, but the vaccine is immunogenic in these patients who are at high risk of invasive pneumococcal disease.

Fibrin (ogen)-derived peptide Bβ 30–43 is a sensitive marker of activated neutrophils during fibrinolytic-treated acute myocardial infarction in man

Neutrophils, elastase, the specifically elastase-derived fibrin split product, Bβ 30–43, and C-reactive protein were determined in 30 consecutive patients with acute myocardial infarction. At admission to the coronary care unit 4.2 ± 0.8 hours after the onset of symptoms, all elements were increased above the reference levels, while compared with convalescent levels, only neutrophils and Bβ 30–43 were increased. After the streptokinase treatment, neutrophils, elastase, and Bβ 30–43 increased abruptly and peaked ( p < 0.0001) within 1.5 hours. Plasma creatine kinase MB and C-reactive protein reached their peak levels after about 12 and 24 hours, respectively. Peak indices of neutrophils and creatine kinase correlated ( r = 0.60, p < 0.0006). Compared with the age-matched reference range, the convalescent level of Bβ 30–43 was increased ( p < 0.0001). Of the tested elements suggestive of neutrophil activation, Bβ 30–43 showed signs of being the most sensitive. In keeping with animal studies, neutrophils are activated early during the course of acute myocardial infarction and their activation seems to become accelerated by fibrinolytic treatment. Neutrophils may remain activated in the convalescent phase.

Frequency and clinical significance of Lyme seropositivity in patients with isolated optic neuritis

We evaluated antibody reactivity against Borrelia burgdorferi in 20 consecutive patients with newly diagnosed isolated optic neuritis who resided in a region endemic for Lyme disease. Four (20%) patients had positive serology. All three patients who had follow-up serologies showed rising convalescent levels of Borrelia-specific IgM. One patient refused lumbar puncture, one had normal CSF constituents except for an elevated Lyme antibody index, and two had CSF lymphocytic pleocytosis that remained unexplained after extensive evaluations for causes other than Lyme disease. We treated both patients who had CSF pleocytosis with intravenous ceftriaxone; the pleocytosis and optic nerve function improved. The other two patients received oral antibiotics and showed excellent recovery of visual acuity. We believe that serologic testing for Lyme disease is warranted for individuals with optic neuritis who reside in an endemic region, and patients with rising convalescent antibody levels or unexplained CSF pleocytosis should receive antibiotic treatment for Lyme disease.

Avian Influenza Antibody Detection by Immunodiffusion

Convalescent levels of influenza antibodies were demonstrated by an agar gel precipitin (AGP) test in turkey sera after field outbreaks. The AGP test was positive with chicken sera for at least 8 weeks after laboratory exposure to any of 3 influenza strains, and positive with turkey sera for at least 12 weeks after exposure. The AGP test facilitates a diagnosis of avian influenza using a suspect virus or paired sera without the influences of strain-to-strain antigenic differences, which limit the usefulness of the hemagglutination-inhibition test.

Serum gonadotropin levels during medical stress (myocardial infarction)

Twenty-one men and 10 postmenopausal women with acute myocardial infarction were studied for changes in circulating gonadotropin levels (radioimmunoassay). In the men the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) values did not change significantly during the first 5 days and were similar to convalescent levels. The values also did not differ significantly from a group of normal men. Postmenopausal women demonstrated a wide range of values and frequently marked daily fluctuations which were probably not induced by the myocardial infarction.

RUBELLA ANTIBODY DETERMINATIONS

Four methods were used to determine rubella antibody titers in patients with acquired and congenital rubella and in gamma-globulin. These methods include hemagglutination inhibition (HI), neutralization (Neut), fluorescence (FA), and complement fixation (CF). With acquired rubella, all four methods showed a rapid development of antibody shortly after the occurrence of rash. Maximum titers appeared within a few weeks, following which HI and CF titers began to decrease and the FA tests showed a weakening of fluorescence. HI titers were four- to sixteenfold higher than Neut, FA, and CF levels. Ten or 20 years after rubella, HI, Neut, and FA tests continued to show detectable antibody but half of the patients no longer had CF antibody. HI titers were still higher than Neut and FA but were considerably lower than convalescent levels. There was complete agreement between HI and Neut tests in the detection of antibody in young adults. For congenital rubella, HI, Neut, and FA antibody persisted in the affected children at least through adolescence. HI and CF antibody increased occasionally during the period 8 to 12 months after birth. Gamma-globulin titers with the HI and Neut methods were in close agreement. Convalescent rubella gamma-globulin gave titers two- to fourfold higher than standard commercial gamma-globulin. Variations in the HA and HI tests were caused by modification of the method of treatment of the antigen, the concentration of red cells used, the size of the test (macro versus micro), the pH of the test, and the treatment of sera. The most significant effects were related to the treatment used to eliminate nonspecific inhibitors in the sera. Improper treatment can give false negative or false positive tests. When properly performed and appropriately controlled, the HI test gives results essentially identical to the Neut method, although the titers are consistently higher than the Neut test. This new method, then, is rapid and convenient for obtaining reliable information on the antibody status and susceptibility of patients.