Introduction Some studies suggest that the monovalent mRNA-1273 vaccine is more effective than BNT162b2 in producing higher levels of antibodies. However, limited data are available, and the methods used are not directly comparable. Material and methods Blood samples were obtained before the booster (third dose) and after 14, 90, and 180 days in two similar cohorts who received the original BNT162b2 or mRNA-1273 vaccine designed to target wild type SARS-CoV-2. The aim of our study is to compare their effectiveness by assessing the levels of binding and neutralizing antibodies specifically against each of the BA.1 variant, BA.5 variant, and the XBB.1.5 subvariant. Results Once the peak was reached after two weeks, a drastic decline in binding and neutralizing antibodies was observed up to 6 months after the homologous booster administration. The humoral response was however more sustained with the mRNA-1273 booster, with half-lives of 167, 55, and 48 days for binding, BA.1, and BA.5 neutralizing antibodies compared to 144, 30, and 29 days for the BNT162b2 booster, respectively. Compared to the BA.1 variant, the neutralizing capacity was significantly decreased at 6 months with the BA.5 variant (fold-decrease: 1.67 to 3.20) and the XBB.1.5. subvariant (fold-decrease: 2.86 to 5.48). Conclusion Although the decrease in the humoral response was observed with both mRNA vaccines over time, a more sustained response was observed with the mRNA-1273 vaccine. Moreover, the emergence of Omicron-based variants causes a reduced neutralizing capacity, notably with the XBB.1.5. subvariant. The administration of subsequent boosters would therefore be needed to restore a sufficiently high neutralizing response.

Introduction Studies about the duration of the humoral and cellular response following the bivalent booster administration are still scarce. We aimed at assessing the humoral and cellular response in a cohort of healthcare workers that received this booster. Material and methods Blood samples were collected before the administration of the bivalent booster from Pfizer-BioNTech and after 14, 28, 90, and 180 days. Neutralizing antibodies against either the D614G strain, the delta variant, the BA.5 variant, or the XBB.1.5 subvariant were measured. The cellular response was assessed by measurement of the release of interferon gamma (IFNγ) from T cells in response to an in vitro SARS-CoV-2 stimulation. Results A substantial waning of neutralizing antibodies was observed after 6 months (23.1‐fold decrease), especially considering the XBB.1.5 subvariant. The estimated T of neutralizing antibodies was 16.1 days (95% CI=10.2–38.4 days). Although most participants still present a robust cellular response after 6 months (i.e., 95%), a significant decrease was also observed compared to the peak response (0.41 versus 0.95 UI/L, p=0.0083). Conclusion A significant waning of the humoral and cellular response was observed after 6 months. These data can also help national competent authorities in their recommendation regarding the administration of an additional booster.

IntroductionAn increase evasion of the SARS-CoV-2 virus towards vaccination strategies and natural immunity has been rapidly described notably due to mutations in the spike receptor binding domain and the N-terminal domain.Material and methodsParticipants of the CRO-VAX HCP study who received the bivalent booster were followed at 6 months. A pseudovirus‐neutralization test was used to assess the neutralization potency of antibodies against D614G, Delta, BA.1, BA.5, XBB.1.5, BA.2.86, FL.1.5.1, and JN-1.ResultsThe neutralizing capacity of antibodies against Omicron variant or subvariants was significantly reduced compared to D614G and Delta (p<0.0001). The lowest neutralizing response that was observed with JN-1 (GMT=22.1) was also significantly lower compared to XBB.1.5 (GMT=29.5, p<0.0001), BA.2.86 (GMT=29.6, p<0.0001), and FL.1.5.1 (GMT=25.2, p<0.0001). Participants that contracted a breakthrough infection due to XBB.1.5 had significantly higher neutralizing antibodies against all variants compared to uninfected participants, especially against Omicron variant and subvariants.ConclusionOur results confirm that JN.1 is one of the most immune evading variants to date and that the BA.2.86 subvariant did not show an increased immunity escape compared to XBB.1.5. The stronger response in BKI with Omicron variant and subvariants supports the need to use vaccine antigens that target circulating variants.

Studies about the evaluation of the humoral and cellular response following the bivalent booster administration are still scarce. The aim of this study was to assess the humoral and cellular response in a cohort of healthcare workers that received either the BA.1 or the BA.4/5 bivalent booster. Blood samples from participants were collected before the administration of either the BA.1 or BA.4/5 bivalent booster from Pfizer-BioNTech and after 14, 28, and 90 days. The humoral response was evaluated using neutralizing antibodies against the BA.5 Omicron variant and binding total and IgG antibodies. The cellular response was assessed by measurement of the release of interferon gamma (IFNγ) from T cells in response to an in vitro SARS-CoV-2 stimulation. Although most participants still had a robust cellular response before the booster, a significant increase in the cellular response was observed after 2 weeks, especially in participants presenting lower levels of IFNγ before the booster administration. Levels of IFNγ remained stable at 3 months and contrast sharply with the rapid decrease of BA.5-specific neutralizing antibodies. Binding antibodies were only modestly correlated to the neutralizing capacity. The evolution of the humoral and cellular response was non-significantly different between participants that received the BA.1 or the BA.4/5 bivalent booster. The monitoring of the humoral and cellular response could be useful to identify patients with a poor adapted immunity that would need to benefit first from an additional booster shot.

Abstract Objectives The BNT162b2 messenger RNA vaccine is highly effective in reducing COVID‐19 infection, hospitalization and death. However, many subjects developed a breakthrough infection despite a full vaccination scheme. Since the waned efficacy of mRNA vaccines is correlated with the decrease of antibodies occurring over time, we aimed at evaluating whether lower levels of antibodies were associated with an increased risk of breakthrough infection in a cohort of breakthrough subjects that received three vaccine doses. Methods Total binding antibodies against the RBD of the S1 subunit (Roche Diagnostics, Machelen, Belgium) and neutralizing antibodies using the Omicron B.1.1.529 variant pseudovirus were measured. Based on individual kinetic curves, the antibody titer of each subject was interpolated just before the breakthrough infection and compared to a matched-control group that did not develop a breakthrough infection. Results Lower levels of total binding and neutralizing antibodies were observed compared to the control group (6.900 [95% CI; 5.101–9.470] vs. 11.395 BAU/mL [8.627–15.050] [p=0.0301] and 26.6 [18.0–39.3] vs. 59.5 dilution titer−1 [32.3–110] [p=0.0042], respectively). The difference between breakthrough and control subjects was mostly observed for neutralizing antibodies before three months after the homologous booster administration (46.5 [18.2–119] vs. 381 [285–509] [p=0.0156]). Considering the measurement of total binding antibodies before 3 months, there was no significant difference (p=0.4375). Conclusions In conclusion, our results showed that subjects that developed a breakthrough infection had lower levels of neutralizing and total binding antibodies compared to controls. The difference was mostly noticeable considering neutralizing antibodies, especially for infections occurring before 3 months after the booster administration.

Dear Editor, Despite a substantial reduction in humoral immunity, COVID-19 vaccines still show robust protection against severe COVID-19 disease, even against highly mutated variants.1Wherry E.J. Barouch D.H. T cell immunity to COVID-19 vaccines.Science. 2022; 377 (PubMed PMID: 35981045. Epub 20220818): 821-822Crossref PubMed Scopus (72) Google Scholar, 2Moss P. The T cell immune response against SARS-CoV-2.Nat Immunol. 2022; 23 (PubMed PMID: 35105982. Epub 2022/02/03): 186-193Crossref PubMed Scopus (521) Google Scholar Accumulating evidence suggests that T cell response plays a key role in the protection against severe disease (i.e., hospitalization and death).1Wherry E.J. Barouch D.H. T cell immunity to COVID-19 vaccines.Science. 2022; 377 (PubMed PMID: 35981045. Epub 20220818): 821-822Crossref PubMed Scopus (72) Google Scholar, 3Ledford H. 'Killer' immune cells still recognize Omicron variant.Nature. 2022; 601 (PubMed PMID: 35017690. Epub 2022/01/13): 307Crossref PubMed Scopus (13) Google Scholar, 4Lippi G. Mattiuzzi C. Henry B.M. Is cellular immunity the future key for deciphering and monitoring COVID-19 vaccines efficacy?.J Lab Precis Med. 2022; 7Crossref Scopus (7) Google Scholar Two recent papers published in Journal of Infection5Pighi L. Henry B.M. De Nitto S. Salvagno G.L. Lippi G. Cellular immunity against SARS-CoV-2 depends on the serological status.J Infect. 2023; (Epub ahead of print)https://doi.org/10.1016/j.jinf.2023.04.003Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar, 6Bonnet B. Chabrolles H. Archimbaud C. Brebion A. Godignon M. Dutheil F. et al.Comparative T and B immune responses of four different anti-COVID-19 vaccine strategies 6 months after vaccination.J Infect. 2022; 84: e45-e47Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar found that the cellular immunity as assessed with an interferon gamma (IFNγ) release assay (IGRA) declined progressively 6–12 months after full vaccination with various COVID-19 vaccines, especially in those with no history of SARS-CoV-2 infection. In the present study, we would like to confirm these findings and to show the impact of the second booster administration on the cellular immunity; a feature not explored in the two above-mentioned studies. On September 2022, 54 participants of the CRO-VAX-HCP study7Favresse J. Gillot C. Bayart J.L. David C. Simon G. Wauthier L. et al.Vaccine-induced binding and neutralizing antibodies against Omicron 6 months after a homologous BNT162b2 booster.J Med Virol. 2023; 95e28164Crossref PubMed Scopus (10) Google Scholar received the second and bivalent adapted BNT162b2 booster. Forty were females (median age = 51.0 years; IQR = 43.3–58.8) and 14 were males (median age = 52.5 years; IQR = 43.8–59.8). Age was not different between females and males (p = 0.60, Man-Whitney test). Most of the participants (45/54; 83.3%) had a history of SARS-CoV-2 infection. Blood was collected in lithium heparin and serum separator tubes (BD Vacutainer, Becton Dickinson, New Jersey, USA) just before and 28 days after the booster administration. The study was approved by a central ethical committee (CHU UCL Namur, Yvoir, Belgium; approval number: 2020-006149-21). Total antibodies against the NCP (Roche Diagnostics) were measured using the Elecsys Anti-SARS-CoV-2 assay. Results above 1.0 cut-off index (COI) were considered positive and indicate a previous SARS-CoV-2 infection. Moreover, the T cell-mediated immune response was assessed using the cobas IGRA SARS-COV-2 Tubes and the Elecsys IGRA SARS‑CoV‑2 assay (Roche Diagnostics). The test measures the release of interferon gamma (IFNγ) from T cells in response to an in vitro SARS-CoV-2 stimulation in whole blood samples which have been formerly in contact with SARS-CoV-2 coated antigens.8Salvagno G.L. Pighi L. Henry B.M. Valentini M. Tonin B. Bragantini D. et al.Assessment of humoral and cellular immunity after bivalent BNT162b2 vaccination and potential association with reactogenicity.Clin Chem Lab Med. 2023; (Online ahead of print)https://doi.org/10.1515/cclm-2023-0055Crossref Scopus (6) Google Scholar Median and interquartile range (IQR) were used to present the data. A Mann-Whitney test was used to assess the impact of the second booster on cellular immunity. A multiple comparison test was used to evaluate the effect of anti-NCP levels on the cellular immunity. Results were categorized as<1.0 COI, 1.0–10.0$8COI and>10.0 COI. A Spearman correlation was also performed for the comparison between anti-NCP and IFNγ. Statistical analyses were performed using GraphPad Prism 9.5.1 (GraphPad Software, Massachusetts, USA). p<0.05 was considered statistically significant. Before the second booster administration, we found a significant and positive correlation between anti-NCP and IFNγ (r = 0.39 (95%CI = 0.11–0.61), p = 0.005). Individuals with negative anti-NCP had significantly lower levels of IFNγ as compared to individuals with high anti-NCP, i.e.>10.0 COI (INFγ level of 0.18 versus 1.00 IU/mL, p = 0.007). These data are consistent with those published by Bonnet et al. and Pighi et al.5Pighi L. Henry B.M. De Nitto S. Salvagno G.L. Lippi G. Cellular immunity against SARS-CoV-2 depends on the serological status.J Infect. 2023; (Epub ahead of print)https://doi.org/10.1016/j.jinf.2023.04.003Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar, 6Bonnet B. Chabrolles H. Archimbaud C. Brebion A. Godignon M. Dutheil F. et al.Comparative T and B immune responses of four different anti-COVID-19 vaccine strategies 6 months after vaccination.J Infect. 2022; 84: e45-e47Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar One month after the bivalent booster administration, a significant increase in IFNγ was only observed for individuals with no history of SARS-CoV-2 infection (from 0.18 to 0.51 IU/mL, fold-increase = 2.85, p = 0.04). Mean fold increase 28 days after the bivalent booster in individuals with positive anti-NCP was close to 1 (i.e., 1.09 and 1.02) (Table 1 and Fig. 1). Additionally, the correlation between anti-NCP and IFNγ was no longer significant after the second booster administration (r = 0.14 (−0.14 to 0.40), p = 0.30).Table 1INFγ levels before and after the bivalent booster in subjects with low (<1.0 COI), intermediate (1–10 COI) and high (>10 COI) anti-NCP antibodies.Anti-NCP (COI)Before boosterAfter boosterFold-increaseP value<1(n = 9)0.18 IU/mL95%CI: 0.08–0.900.51 IU/mL95%CI: 0.33–1.872.850.04(*)1–10(n = 21)0.63 IU/mL95%CI: 0.36–0.730.69 IU/mL95%CI: 0.40–1.61.090.22(ns)>10(n = 24)1.00 IU/mL95%CI: 0.48–2.301.02 IU/mL95%CI: 0.60–1.931.020.97(ns) Open table in a new tab Based on these findings, we confirm that individuals with no history of SARS-CoV-2 infection presented a reduced cellular immunity but were those that were more susceptible to benefit from a second booster in terms of cellular immunity. These findings need to be confirmed in other studies with a larger population. None declared.

Background: Anti-Xa assays are used for unfractionated heparin (UFH) monitoring. Dextran sulfate (DS) is used in some assays to overcome the artifactual preanalytical release of platelet factor 4. However, the practical implications of this test modification have not been studied extensively.Objectives: To investigate the impact of the presence of DS in the anti-Xa assay for UFH laboratory monitoring.Methods: We studied factor Xa inhibition, using an assay without DS (Stago Liquid Anti-Xa), in normal pool plasma spiked with various concentrations of UFH (up to 1 IU/ mL) in the presence of increasing concentrations of DS (up to 2560 mu g/mL). We also investigated the effect of DS on FXa inhibition measured after the addition of UFH and heparin antagonists (protamine and Polybrene; Sigma Aldrich). Eventually, we compared the anti-Xa levels measured using the assay without DS to those measured with an assay containing DS (BIOPHEN Heparin LRT, Hyphen BioMed). Results: DS per se had a detectable anti-Xa effect. FXa inhibition in UFH-spiked plasma linearly increased with increasing concentrations of added DS, with a plateau at approximately 160 mu g/mL DS, at which the apparent anti-Xa level had almost doubled. In the presence of heparin antagonists, the addition of DS increased anti-Xa levels, corresponding to the dissociation of the UFH-antagonists complexes in vitro. With the anti-Xa assay containing DS, UFH inhibition was not detected. Conclusion: In the presence of high concentrations of DS, FXa inhibition was much higher than that predicted from added UFH amounts, presumably related to the greater availability of UFH for interaction with antithrombin. While the relevance of measuring this "masked" heparin has not been demonstrated, the presence of DS renders the result inaccurate in the presence of protamine or Polybrene.

Introduction: Urinalysis is essential for diagnosing kidney-related medical conditions. Urine test strip analysis serves as an initial and efficient screening method for reflex testing with accurate quantitative methods.Materials and Methods: Freshly voided urines (n = 206) were analysed using two urine test strip brands on UCMAX (Menarini) and cobas u 601 (Roche Diagnostics) instruments. Ordinal scale categories and reflectance signals (if available) were both used for the comparison with reference quantitative methods for glucose, proteins and albumin (cobas 503). Samples were considered positive when glucose > 15 or >= 54 mg/dL, proteins >= 200 mg/L and albumin >= 10 mg/L. Optimized reflectance thresholds were calculated by ROC curve analysis. Analytical performance specifications (APS) for trueness of test strip were gathered from the EFLM guideline (FPD, FNG, FNC).Results: Reflectance signals were significantly lower in urine samples considered positive by the reference method (p < 0.0001). Reflectance signals were also correlated with quantitative measurements, showing strong correlation (0.754 to 0.969). Only the use of optimized reflectance thresholds on cobas u 601 achieved at least the minimum EFLM APS (FPD < 20%, FNG < 50% and FNC < 10%).Conclusion: The use of reflectance signals from urine test strips enhanced accuracy for glucose, proteins, and albumin measurement and may contribute to improve diagnosis of diverse kidney-related conditions.

Les épreuves classantes nationales informatisées (ECNi) s’appuient actuellement sur une évaluation des connaissances des étudiants et non des compétences cliniques, pourtant déterminantes dans la performance professionnelle. Pour évaluer l’impact potentiel de cette absence de considération, nous avons évalué la concordance entre les rangs des étudiants aux épreuves facultaires cliniques et leur rang aux ECNi.Nous avons inclus les étudiants de 6e année de médecine à Sorbonne Université des promotions 2017 à 2021 et récupéré leurs notes et rangs aux épreuves facultaires théoriques et cliniques et aux ECNi. Les épreuves théoriques sont au même format que les ECNi. Les épreuves cliniques comprennent une évaluation sémiologique au lit du malade et une évaluation des compétences relationnelles lors de deux entretiens cliniques simulés. Nous avons étudié la concordance entre les épreuves facultaires et les ECNi par le coefficient de corrélation intraclasse (CCI).Nous avons inclus 1806 étudiants. La concordance entre le rang aux épreuves facultaires théoriques et le rang aux ECNi est bonne (CCI 0,83; IC 95 % 0,81–0,85) alors que la concordance entre le rang aux épreuves facultaires cliniques et le rang aux ECNi est médiocre (CCI 0,13; IC 95 % 0,09–0,17).L’accord entre le rang de classement aux ECNi et les compétences cliniques évaluées par une épreuve facultaire spécifique est actuellement faible. Incorporer une évaluation pratique dans le classement national, comme le prévoit la réforme du deuxième cycle, motivera l’ensemble des étudiants à investir des efforts dans l’acquisition des compétences cliniques et valorisera les plus performants dans cette dimension.Before attending residency, 6th-year French medical students must validate a final examination including a practical clinical test in their faculty. However, the national ranking that determines their future specialty and region solely relies on a computerized knowledge test. Our goal was to investigate the association between the final faculty test and the national ranking test.In our faculty, the final examination includes a computerized theoretical test (similar to the national one) and a practical test: a standardized evaluation of semiology skills at the bedside and a standardized assessment of relational skills with role plays. The agreements between the national test and faculty computerized and practical tests were analyzed by intraclass correlation coefficients (ICC).Data from 1806 students who underwent the three examinations from 2017 to 2021 were analyzed. There was a good agreement between the ranks in the faculty and national computerized tests: ICC 0.83 (95% CI 0.81–0.85). By contrast, the agreement between the ranks in the faculty practical test and the national computerized test was poor: ICC 0.13 (95% CI 0.08–0.17). Results were stable over the years.The agreement between the ranking of the current national test and the clinical skills assessed by a specific faculty test is poor. This could relate to a true independence or to different levels of motivation to perform well. Indeed, the result of the national test is the most important one as it determines their career. Incorporating a clinical assessment into the national ranking test will motivate students to acquire clinical skills and value those who perform well this practical dimension.

INTRODUCTION:Lupus anticoagulant (LA) testing requires normal pooled plasma (NPP) in performing mixing studies and can be used for normalized ratios of clotting times (CTs). The aims were to demonstrate whether significant differences in clotting times between two batches of a same commercial NPP (CRYOcheck™) directly affect NPP-based cut-off values.METHODS:Diluted Russell Viper venom time (DRVVT) and activated partial thromboplastin time (aPTT) were used for LA testing. Screening, mixing and confirm tests were performed with Stago® instruments and reagents. Two batches of commercial NPP (A1291 and A1301 from CRYOcheck™; frozen) were compared in the determination of cut-off values. Cut-off values were defined as 99th percentile values of 60 healthy donors and compared with Mann-Whitney U test.RESULTS:Cut-off values obtained with the two NPP batches were significantly different for DRVVT (screen normalized ratio: 1.09 vs. 1.24, screen mix: 41.9 s vs. 38.9 s; index of circulating anticoagulant: 5.0 vs. 8.4; all had p-value <.001). On the contrary, no significant differences were observed for aPTT (screen normalized ratio: 1.32 vs. 1.34; p-value = .4068, screen mix: 37.8 s vs. 38.1 s; p-value = .1153) except for index of circulating anticoagulant: 9.6 versus 10.4 (p-value <.05).CONCLUSION:This study demonstrates that differences between two commercial NPP batches produced by a same manufacturer influenced LA cut-off values used for mixing studies and normalized ratios. Adequate cut-off setting, taking into account NPP CTs, is important to provide accurate conclusion about the presence or absence of a LA and avoid potential clinical impact.