Prinsippemeriksaan kuantitatif antibodi spesifik SARS COV 2 ini menggunakan pemeriksaan laboratorium imunoserologi pada sebuah alat automatik (autoanalyzer) untuk mendeteksi antibodi terhadap SARS-CoV-2 atau pemeriksaan ini biasa disebut dengan ECLIA (ELECTRO CHEMILUMINESCENCE IMMUNOASSAY). PemeriksaanAntis SARS-CoV 2 S Kuantitatif metode CMIA digunakan mengukur antibodi kuantitatif termasuk IgG pada receptor binding domain (RBD) protein Spike (S) SARS-CoV-2 dengan tujuan menilai respons imun humoral adaptif terhadap protein Spike SARS-CoV-2. Apa informasi penting tentang Paket Pencegahan & Screening Covid-19? WantaiELISA titer <1:80, Euroimmun IgG titers <1:640 or Diasorin Anti-SARS-CoV-2 values <30 AU/mL can aid in the selection of suitable donors. All three tests were able to exclude low NT titer products with a high likelihood (NPV of low results: 94.2 %, 95.1 % and 97.3 %). In identifying donors with high NT titers (>1:200) the Wantai was Minimal2 minggu setelah vaksin dosis ke 2, seseorang sudah bisa melakukan pemeriksaan Anti-SARS-CoV-2 Kuantitatif. Anti-SARS-CoV-2 Kuantitatif merupakan jenis pemeriksaan untuk mendeteksi suatu protein yang disebut antibodi, khususnya antibodi spesifik terhadap Corona Virus. Jadi, dengan melakukan pemeriksaan ini seseorang bisa mengetahui Yukkcari tahu dengan test Anti Sars CoV-2 di Laboratorium Klinik Populer. Tenang aja, harga terjangkau dan Ada promo Khusus Harga Cuma 200 ribu dan Anda juga bisa mengetahui kondisi kesehatanmu secara berkala dengan pemeriksaan penunjang lainnya. PROMO INI JUGA BISA KAMU NIKMATI DI SEMUA CABANG LABORATORIUM KAMI DI. Jl. PEMERIKSAANAnti-SARS-CoV-2 Kuantitatif ialah pemeriksaan yang dapat mengukur titer antibodi atau antibodi penetral dalam tubuh seseorang terhadap virus penyebab Covid-19. Pemeriksaan ini mampu mengevaluasi respons imun seseorang terhadap virus SARS-CoV-2 sehingga memungkinkan dokter menilai respons imun pada virus dari waktu ke waktu. nRFe. Dear Editor,The Coronavirus disease 2019 COVID-19 pandemic has caused over 670 million cases and million deaths worldwide, many of which are attributed to cardiovascular complications. Virus-induced endothelial damage, endothelial barrier dysfunction, thrombosis, and cytokine storm are implicated in heart and multi-organ failure. The prognosis is worsened by comorbidities, including diabetes and arterial hypertension, characterized by an inflammatory and pro-thrombotic milieu and upregulation of total and glycosylated Angiotensin-Converting Enzyme 2 ACE2 in pericytes represent a preferential target of SARS-CoV-2 These perivascular cells preserve vascular integrity through physical and paracrine crosstalk with capillary endothelial cells. Pericyte dysfunction and detachment favor the SARS-CoV-2 to spread from the bloodstream and damage the infection starts with the engagement of the Spike S-protein with its cellular ACE-2 and CD147 receptors. Due to the homology with human proteins, the S-protein also acts as a natural ligand activating the ERK1/2 MAPK signaling pathway in cardiac Some evidence suggests that the S-protein, CD147, cyclophilin, and MAPK axis are essential in triggering the cytokine However, an in vivo demonstration of the S-protein’s direct damaging effect on cardiac pericytes is present study investigated the acute effects of intravenously injected S-protein on the heart microvasculature of otherwise healthy mice. Moreover, we analyzed the expressional changes caused by the S-protein in primary cultures of human cardiac pericytes using bulk RNA-Sequencing. Finally, the RNA-Sequencing data were cross-referenced with single-nuclei sn-RNA-Sequencing datasets of COVID-19 patients’ hearts to determine how expressional changes after SARS-CoV-2 infection overlap with those caused by the S-protein healthy CD1 mice 6 male, 6 female were randomized to receive either 10 µg endotoxin-free S-protein resuspended in 100 µL sterile PBS or PBS only, intravenously. They were culled three days later for molecular and histological analyses Fig. 1a. S-protein immunoreactive levels in the circulation were like those reported in COVID-19 patients early after infection and before seroconversion ± ng/mL.7 Immunohistochemistry of the hearts demonstrated that the S-protein, although not altering the capillary density, increased the fraction that expresses ICAM-1, an adhesion molecule implicated in leucocyte-endothelial interactions Fig. 1b and remarkably reduced the pericyte density, coverage, and viability Fig. 1c–e. SARS-CoV-2 can trigger direct or indirect activation of all three complement Here, we show that the in vivo administration of S-protein increased complement-activated C5a protein levels in peripheral blood and the heart Fig. 1f, g. Moreover, the S-protein increased the heart’s abundance of CD45+ immune cells ± cells/mm2 vs. ± cell/mm2 in PBS-treated mice, specifically Ly6G/6C+ neutrophils/monocytes Fig. 1h and F4/80+ macrophages Fig. 1i. Leucocytes can crawl along pericyte processes to enlarged gaps between adjacent pericytes in an ICAM-1-dependent manner during inflammation. Controls for immunohistochemistry stainings are provided in Supplementary Fig. 1a–i Injection of S-protein in vivo in mice. a Experimental design of the in vivo study in mice. b Representative immunofluorescence images of mice hearts showing capillaries IB4, green and activated endothelium ICAM-1, red. Bar graphs summarize the quantitative analysis of capillaries positive for ICAM-1, expressed as a percentage of total vessels. c Representative immunofluorescence images showing capillaries IB4, green and pericytes PDGFRβ, red. Bar graphs summarize the quantitative analysis of pericyte density. d Representative immunofluorescence images showing longitudinal capillaries IB4, green covered by pericytes PDGFRβ, red. Bar graphs report the quantitative analysis of pericyte coverage. e Representative immunofluorescence images of mice hearts showing endothelial cells IB4, green, pericytes PDGFRβ, red, and TUNEL-positive nuclei apoptotic nuclei, magenta. Bar graphs report the quantification of TUNEL+ pericytes. f Measurement of C5a in mice plasma using ELISA. g Immunohistochemistry/DAB staining and a bar graph showing the accumulation of the activated complement factor C5a in the mice hearts. Nuclei are shown in blue Haematoxylin. The graph reports the integrated optical density IOD values. Representative immunofluorescence images of mice hearts showing the presence of neutrophils/monocytes h—Ly6G/6 C, green and macrophages i—F4/80, green. Cardiomyocytes are labeled with α-Sarcomeric Actin red. Bar graphs report the density of Ly6G/6 C+ neutrophils/monocytes and F4/80+ macrophages. In all immunofluorescence images, DAPI labels nuclei in blue. For all images, the scale bar is 50 μm. For all analyses, n = 6 per group. All data are presented as individual values and means ± SEM. Statistical tests after a normality test, an unpaired t-Test was applied. j–l RNA-Sequencing analysis of human cardiac pericytes challenged with the S-protein in vitro. n = 3 patients. j Experimental design and volcano plot showing transcripts differentially expressed in S-protein-treated nM human cardiac pericytes vs. PBS vehicle-treated pericytes. The terms of the most relevant genes were reported. k Bar graph indicating all differentially expressed KEGG pathways. l Bar graphs indicating the most relevant differentially expressed Reactome pathways. FDR = false discovery rate. Genes were considered differentially expressed for FDR ≤ m–p Sn-RNA-Sequencing analysis of pericytes from COVID-19 patients’ hearts. n = 22 COVID patients, n = 25 controls. m Plots show the ordering of pericytes in pseudo-time. The starting point of pseudo-time is from the pericytes of healthy donors. n A heatmap summarizing the mean expression of normalized unique molecular identifiers UMIs of genes in the modules resulting from the pseudo-time analysis. o A volcano plot showing fold-change of module expression COVID-19 compared to healthy donors and enrichment significance of each module and differentially expressed genes from bulk RNA-Sequencing comparing PBS-vehicle and Spike. p A plot summarising overlapped/similar Reactome and Gene Ontology terms overrepresented in each module and differentially expressed genes in bulk RNA-Sequencing. q Schematic summarizing major findings and candidate mechanisms underpinning the S-protein damaging action. Left panel We provide novel evidence that S-protein alone can damage the heart microvasculature of otherwise healthy mice. On one side, the S-protein acts as a ligand activating intracellular pericyte signaling, which results in pericyte detachment, death, and decreased vascular coverage, thus disrupting the coronary microcirculation. On the other, the S-protein triggers endothelial activation ICAM-1+ endothelial cells, resulting in increased homing of leukocytes to the heart and accumulation of activated complement protein C5a. Right panel A comparison between the expressional changes induced by the S-protein in primary human cardiac pericytes in vitro and single-nuclei sn-RNA-Sequencing pseudo-time trajectories analysis in pericytes extracted from the heart of deceased COVID-19 patients revealed overlapping expressional responses as indicated. These findings suggest that at least some of the in vivo effects of SARS-CoV-2 on human cardiac pericytes may be due to the modulation of inflammatory and epigenetic pathways triggered by the S-protein interaction with its cell surface receptors. The drawing was created with size imageTo further validate the theory of the S-protein acting as a direct transcriptomic influencer, we added it or the PBS vehicle to human primary cardiac pericytes in vitro for 48 h. RNA-Sequencing analysis indicated the differential modulation of 309 RNA transcripts, with 201 genes being up-regulated and 108 genes down-regulated by the S-protein at FDR < Fig. 1j. KEGG pathway analysis showed an overrepresentation of inflammatory pathways, for example, TNF, IL-17, and NF-kappa B signaling pathways, cytokine-cytokine receptor interaction, and cell adhesion molecules CAMs. Moreover, there was an enrichment for pathways associated with infectious diseases, including Legionellosis, Pertussis, Malaria, Herpes virus, and Epstein-Barr virus infection Fig. 1k. An overview of the pathway analysis based on the Reactome database further pinpointed the transcriptional induction of cytokine signaling pathways, such as IL-10, IL-4, and IL-13 signaling and Toll-like receptor cascade Fig. 1l and Supplementary Fig. S2, and the downregulation of pathways implicated in histone deacetylation and methylation and chromatin modification, and RNA polymerase-related mechanisms controlling promoter opening and clearance, transcription, and chain elongation Fig. 1l and Supplementary Fig. S2. The analysis of modulated biological processes confirmed the upregulation of cellular responses to stress and the downregulation of homeostatic responses associated with healing and angiogenesis processes Supplementary Fig. S3. A comprehensive list of regulated pathways is provided in Supplementary Dataset to dissect clinically relevant targets further, we cross-interrogated the transcriptional landscape of pericytes exposed in vitro to the recombinant S-protein and pericytes from the hearts of COVID-19 patients. Additionally, we employed a pseudo-time inference approach to probe individual genes’ expression dynamics along with the progression of the disease. To this aim, we extracted pericytes from the integrated Seurat, R object downloaded from Delorey et al., 20219 using marker genes followed by a pseudo-time analysis of pericytes collected from the heart of COVID-19 patients Fig. 1m. The pseudo-time analysis allowed the identification of pericyte genes that are differential and co-expressed along the trajectory. This resulted in the recognition of 37 gene clusters Fig. 1n. Next, to identify common signals between ex vivo and in vivo datasets, we tested for the overrepresentation of expressional changes in pericytes exposed to S-protein and gene clusters in the human heart. We observed that seven gene clusters 1, 2, 6, 13, 15, 20, and 27, FDR < significantly overlapped with the expressional changes observed in pericytes exposed to the S-protein experiment Fig. 1o. Cluster 15 was enriched for cytokine-related pathways, metallothioneins, and regulation of histone acetylation, while clusters 1, 6 and 27 were overrepresented for extracellular matrix organization, elastic fibre formation, and integrin cell surface interactions Fig. 1p and Supplementary Dataset 2. Studies have reported that COVID-19 can cause cardiovascular complications due to impaired extracellular matrix organisation and reduced elastic fibre levels, potentially leading to blood These findings suggest a convergence of signals that proteins of the virion envelope mediate at least part of the transcriptional changes induced by the virus in the hearts of infected people. Therefore, some of the in vivo effects of SARS-CoV-2 on human cardiac pericytes may be attributable to the interaction between the S-protein and the host’s transcriptomic program modulating inflammatory and epigenetic we performed drug target enrichment analysis using the LINCS L1000CDS and DrugBank databases. This analysis allowed us to identify drugs that reverse the expressional changes induced by the S-protein in pericytes Supplementary Dataset 3 and 4. Among the top fifty compounds, we found a prevalence of anti-tumoral, pro-apoptotic, anti-viral, anti-inflammatory and anti-thrombotic drugs, some of which have already been trialed in COVID-19 patients. Although more research is needed to determine if pharmacological interference with the signaling emanating from the S-protein can alleviate COVID-19 outcomes, these data suggest a competitive effect of anti-inflammatory and anti-tumoral drugs. In addition, several compounds like Quercetin or ubiquitin-conjugating enzyme inhibitors may help moderate inflammation by eliminating S-Protein-induced senescent summarized in Fig. 1q provide novel evidence of the SARS-CoV-2 S-protein’s direct pathogenic action on cardiac pericytes and the heart’s microvasculature. It is plausible that the harmful effects observed in healthy mice three days after a single systemic injection of the S-protein might be intensified in the presence of cardiovascular risk factors and prolonged exposure. These possibilities merit further investigation. Moreover, we showed that the S-protein modifies the transcriptional program of human cells to the virus’ advantage. This new information could have significant implications for the treatment of COVID-19, for instance, using anti-S-protein engineering approaches to protect vascular cells. Data availabilityThe article’s data can be obtained as reasonably required from the corresponding author. The main datasets underlying transcriptomic analyses are provided as supplementary datasets Dataset 1–4. The bulk RNA-Seq raw data have been deposited in NCBI’s Gene Expression Omnibus and are accessible through GEO Series accession number N. et al. Glycated ACE2 receptor in diabetes open door for SARS-COV-2 entry in cardiomyocyte. Cardiovasc. Diabetol. 20, 99 2021.Article PubMed PubMed Central Google Scholar Sardu, C. et al. Could Anti-Hypertensive Drug Therapy Affect the Clinical Prognosis of Hypertensive Patients With COVID-19 Infection? 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The SARS-CoV-2 Spike protein disrupts human cardiac pericytes function through CD147 receptor-mediated signalling a potential non-infective mechanism of COVID-19 microvascular disease. Clin. Sci. 135, 2667–2689 2021.Article CAS Google Scholar Afzali, B., Noris, M., Lambrecht, B. N. & Kemper, C. The state of complement in COVID-19. Nat. Rev. Immunol. 22, 77–84 2022.Article CAS PubMed Google Scholar Delorey, T. M. et al. COVID-19 tissue atlases reveal SARS-CoV-2 pathology and cellular targets. Nature 595, 107–113 2021.Article CAS PubMed PubMed Central Google Scholar Shi, S. et al. Association of Cardiac Injury With Mortality in Hospitalized Patients With COVID-19 in Wuhan, China. JAMA Cardiol. 5, 802–810 2020.Article PubMed PubMed Central Google Scholar Download referencesAcknowledgementsThe authors wish to acknowledge the members of the University of Bristol COVID-19 Emergency Research Group UNCOVER for their scientific support. Drawings were generated with work was supported by the British Heart Foundation BHF project grant “Targeting the SARS-CoV-2 S-protein binding to the ACE2 receptor to preserve human cardiac pericytes function in COVID-19” PG/20/10285 to and European Commission H2020 CORDIS project COVIRNA project/id/101016072 to and and BHF Chair award CH/15/1/31199 to In addition, it was supported by a grant from the National Institute for Health Research NIHR Biomedical Research Centre at University Hospitals Bristol NHS Foundation Trust and the University of Bristol. is a postdoctoral researcher supported by the Heart Research UK translational project grant “Targeting pericytes for halting pulmonary hypertension in infants with congenital heart disease” RG2697/21/23 to and is an investigator of the Wellcome Trust 106115/Z/14/Z.Author informationAuthor notesThese authors contributed equally Elisa Avolio, Prashant K SrivastavaAuthors and AffiliationsBristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UKElisa Avolio, Michele Carrabba, Christopher T. W. Tsang, Yue Gu, Anita C. Thomas & Paolo MadedduNational Heart & Lung Institute, Imperial College, London, UKPrashant K. Srivastava, Jiahui Ji & Costanza EmanueliSchool of Biochemistry, University of Bristol, Bristol, UKKapil Gupta & Imre BergerAuthorsElisa AvolioYou can also search for this author in PubMed Google ScholarPrashant K. SrivastavaYou can also search for this author in PubMed Google ScholarJiahui JiYou can also search for this author in PubMed Google ScholarMichele CarrabbaYou can also search for this author in PubMed Google ScholarChristopher T. W. TsangYou can also search for this author in PubMed Google ScholarYue GuYou can also search for this author in PubMed Google ScholarAnita C. ThomasYou can also search for this author in PubMed Google ScholarKapil GuptaYou can also search for this author in PubMed Google ScholarImre BergerYou can also search for this author in PubMed Google ScholarCostanza EmanueliYou can also search for this author in PubMed Google ScholarPaolo MadedduYou can also search for this author in PubMed Google research conception and design. manuscript writing. histological analyses of mice hearts. cellular and molecular biology experiments. transcriptomic analyses in pericytes. in vivo procedures with mice. production and provision of Spike protein. funding, supervision of transcriptomic studies, and manuscript editing. funding provision. study supervision. All authors data interpretation and manuscript revision. All authors approved the authorship and the final version of the manuscript for authorCorrespondence to Paolo declarations Competing interests The authors declare no competing interests. Ethics declarations The animal study was covered by a license from the British Home Office PPL 1377882 and complied with EU Directive 2010/63/EU. Procedures were carried out according to the principles in the Guide for the Care and Use of Laboratory Animals The Institute of Laboratory Animal Resources, 1996. Termination was conducted according to humane methods outlined in the Guidance on the Operation of the Animals Scientific Procedures Act 1986 Home Office 2014. The collection of human patients’ cardiac waste tissue was covered by the ethical approval number 15/LO/1064 from the North Somerset and South Bristol Research Ethics Committee. Patients gave informed written consent. Supplementary informationRights and permissions Open Access This article is licensed under a Creative Commons Attribution International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original authors and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit Reprints and PermissionsAbout this articleCite this articleAvolio, E., Srivastava, Ji, J. et al. Murine studies and expressional analyses of human cardiac pericytes reveal novel trajectories of SARS-CoV-2 Spike protein-induced microvascular damage. Sig Transduct Target Ther 8, 232 2023. citationReceived 11 January 2023Revised 28 April 2023Accepted 08 May 2023Published 02 June 2023DOI . 2022 Jan;941388-392. doi Epub 2021 Aug 31. Affiliations PMID 34415572 PMCID PMC8426838 DOI Free PMC article Correlation between a quantitative anti-SARS-CoV-2 IgG ELISA and neutralization activity Ramona Dolscheid-Pommerich et al. J Med Virol. 2022 Jan. Free PMC article Abstract In the current COVID-19 pandemic, a better understanding of the relationship between merely binding and functionally neutralizing antibodies is necessary to characterize protective antiviral immunity following infection or vaccination. This study analyzes the level of correlation between the novel quantitative EUROIMMUN Anti-SARS-CoV-2 QuantiVac ELISA IgG and a microneutralization assay. A panel of 123 plasma samples from a COVID-19 outbreak study population, preselected by semiquantitative anti-SARS-CoV-2 IgG testing, was used to assess the relationship between the novel quantitative ELISA IgG and a microneutralization assay. Binding IgG targeting the S1 antigen was detected in 106 samples using the QuantiVac ELISA, while 89 samples showed neutralizing antibody activity. Spearman's correlation analysis demonstrated a strong positive relationship between anti-S1 IgG levels and neutralizing antibody titers rs = p < High and low anti-S1 IgG levels were associated with a positive predictive value of for high-titer neutralizing antibodies and a negative predictive value of for low-titer neutralizing antibodies, respectively. These results substantiate the implementation of the QuantiVac ELISA to assess protective immunity following infection or vaccination. Keywords COVID-19; ELISA; SARS-CoV-2; microneutralization. © 2021 The Authors. Journal of Medical Virology Published by Wiley Periodicals LLC. Conflict of interest statement Sandra Saschenbrecker and Katja Steinhagen are employed by EUROIMMUN Medizinische Labordiagnostika AG, a manufacturer of diagnostic reagents and co‐owner of a patent application pertaining to the detection of antibodies to the SARS‐CoV‐2 S1 antigen. Katja Steinhagen is designated as an inventor. The other authors declare that there are no conflict of interests. Figures Figure 1 Correlation between quantitative ELISA and microneutralization assay. Binding anti‐SARS‐CoV‐2 S1 IgG was determined quantitatively using the QuantiVac ELISA and titers of neutralizing antibodies were determined using the CPE reduction NT assay n = 123. Neutralization titers correspond to reciprocal plasma dilutions protecting 50% of the wells at incubation with 100 TCID50 of SARS‐CoV‐2. Samples with a cytopathic effect CPE equal or similar to the negative control are depicted on the y‐axis. 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Trop Med Infect Dis. 2023 Mar 23;84185. doi Trop Med Infect Dis. 2023. PMID 37104311 Free PMC article. Convalescent Plasma Treatment of Patients Previously Treated with B-Cell-Depleting Monoclonal Antibodies Suffering COVID-19 Is Associated with Reduced Re-Admission Rates. Ioannou P, Katsigiannis A, Papakitsou I, Kopidakis I, Makraki E, Milonas D, Filippatos TD, Sourvinos G, Papadogiannaki M, Lydaki E, Chamilos G, Kofteridis DP. Ioannou P, et al. Viruses. 2023 Mar 15;153756. doi Viruses. 2023. PMID 36992465 Free PMC article. Characterisation of the Antibody Response in Sinopharm BBIBP-CorV Recipients and COVID-19 Convalescent Sera from the Republic of Moldova. Ulinici M, Suljič A, Poggianella M, Milan Bonotto R, Resman Rus K, Paraschiv A, Bonetti AM, Todiras M, Corlateanu A, Groppa S, Ceban E, Petrovec M, Marcello A. Ulinici M, et al. Vaccines Basel. 2023 Mar 13;113637. doi Vaccines Basel. 2023. PMID 36992221 Free PMC article. References Krammer F, Simon F. Serology assays to manage COVID‐19. Science. 2020;3681060‐1061. - PubMed Lee CY, Lin RTP, Renia L, Ng LFP. Serological approaches for COVID‐19 Epidemiologic perspective on surveillance and control. Front Immunol. 2020;11879. - PMC - PubMed Theel ES, Slev P, Wheeler S, Couturier MR, Wong SJ, Kadkhoda K. The role of antibody testing for SARS‐CoV‐2 is there one? J Clin Microbiol. 2020;5858. - PMC - PubMed Zost SJ, Gilchuk P, Case JB, et al. Potently neutralizing and protective human antibodies against SARS‐CoV‐2. Nature. 2020;584443‐449. - PMC - PubMed Rogers TF, Zhao F, Huang D, et al. Isolation of potent SARS‐CoV‐2 neutralizing antibodies and protection from disease in a small animal model. Science. 2020;369956‐963. - PMC - PubMed Publication types MeSH terms Substances LinkOut - more resources Full Text Sources Europe PubMed Central Ovid Technologies, Inc. PubMed Central Wiley Medical Genetic Alliance Miscellaneous NCI CPTAC Assay Portal Evaluation of Three Quantitative Anti-SARS-CoV-2 Antibody Immunoassays Sabine Chapuy-Regaud et al. Microbiol Spectr. 2021. Free PMC article Abstract The severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 emerged in December 2019 and caused a dramatic pandemic. Serological assays are used to check for immunization and assess herd immunity. We evaluated commercially available assays designed to quantify antibodies directed to the SARS-CoV-2 Spike S antigen, either total Wantaï SARS-CoV-2 Ab ELISA or IgG SARS-CoV-2 IgG II Quant on Alinity, Abbott, and Liaison SARS-CoV-2 TrimericS IgG, Diasorin. The specificities of the Wantaï, Alinity, and Liaison assays were evaluated using 100 prepandemic sera and were 98, 99, and 97%, respectively. The sensitivities of all three were around 100% when tested on 35 samples taken 15 to 35 days postinfection. They were less sensitive for 150 sera from late infections >180 days. Using the first WHO international standard NIBSC, we showed that the Wantai results were concordant with the NIBSC values, while Liaison and Alinity showed a proportional bias of and 7, respectively. The results of the 3 immunoassays were significantly globally pairwise correlated and for late infection sera P < They were correlated for recent infection sera measured with Alinity and Liaison P < However, the Wantai results of recent infections were not correlated with those from Alinity or Liaison. All the immunoassay results were significantly correlated with the neutralizing antibody titers obtained using a live virus neutralization assay with the SARS-CoV-2 strain. These assays will be useful once the protective anti-SARS-CoV-2 antibody titer has been determined. IMPORTANCE Standardization and correlation with virus neutralization assays are critical points to compare the performance of serological assays designed to quantify anti-SARS-CoV-2 antibodies in order to identify their optimal use. We have evaluated three serological immunoassays based on the virus spike antigen that detect anti-SARS-CoV-2 antibodies a microplate assay and two chemiluminescent assays performed with Alinity Abbott and Liaison Diasorin analysers. We used an in-house live virus neutralization assay and the first WHO international standard to assess the comparison. This study could be useful to determine guidelines on the use of serological results to manage vaccination and treatment with convalescent plasma or monoclonal antibodies. Keywords COVID; SARS-CoV-2; binding antibodies; immunoassay; neutralizing antibodies. Conflict of interest statement The authors declare no conflict of interest. Figures FIG 1 Distribution of the results. A Wantaï, B Liaison, and C Alinity assays according to patient groups. Black lines = median of each group. Red lines = manufacturer’s negative/positive threshold. Zero 0 values in the Liaison negative group n = 92, the Liaison late infection group n = 15, the Alinity negative group n = 14, and the Alinity late infection group n = 7 are not shown. FIG 2 ROC curves for Wantaï black line, Liaison green line and Alinity red line. Gray line y = x. The AUROCs were Wantaï 95% CI to Liaison 95% CI to and Alinity 95% CI to indicating their capacity to accurately detect anti-SARS-CoV-2 antibodies. FIG 3 Quantification of anti-SARS-CoV-2 antibodies relative to the NIBSC international standard. Serial dilutions of the NIBSC 20/136 standard were assayed with the A Wantaï, B Liaison, and C Alinity assay. Neutralizing antibodies NAb were also determined with a live method D. The black line represents the regression line and the dashed lines its 95% CI. The dashed red line represents the y = x line. AU arbitrary units. BAU binding antibody unit. The equations were y = x − slope 95% CI to y-intercept 95% CI − to for Wantaï; y = x − slope 95% CI to y-intercept 95% CI − to for Liaison; y = x - slope 95% CI to y-intercept 95% CI − to for Alinity and y = x + slope 95% CI to y-intercept 95% CI − to for NAb titers. FIG 4 Correlation between the immunoassay results. Pairwise distribution of the Wantaï, Liaison, and Alinity assays values for all positive results A to C, recent infections D to F, and late infections G to I. When the Spearman rank coefficient r indicated a significant correlation, the regression line was drawn. Dashed lines 95% CI limits. FIG 5 Immunoassays results and neutralizing antibody titers. Distribution of the Wantaï, Liaison, and Alinity assay values and the NAb titers for all positive results A to C The NAb titers were determined in a live virus neutralization assay using the B strain. Spearman’s rank coefficients r and their P value are indicated. The box extends from the 25th to 75th percentiles and whiskers from minimal to maximal values. Similar articles Performance evaluation of three automated quantitative immunoassays and their correlation with a surrogate virus neutralization test in coronavirus disease 19 patients and pre-pandemic controls. Jung K, Shin S, Nam M, Hong YJ, Roh EY, Park KU, Song EY. Jung K, et al. J Clin Lab Anal. 2021 Sep;359e23921. doi Epub 2021 Aug 8. J Clin Lab Anal. 2021. PMID 34369009 Free PMC article. Inference of SARS-CoV-2 spike-binding neutralizing antibody titers in sera from hospitalized COVID-19 patients by using commercial enzyme and chemiluminescent immunoassays. Valdivia A, Torres I, Latorre V, Francés-Gómez C, Albert E, Gozalbo-Rovira R, Alcaraz MJ, Buesa J, Rodríguez-Díaz J, Geller R, Navarro D. Valdivia A, et al. Eur J Clin Microbiol Infect Dis. 2021 Mar;403485-494. doi Epub 2021 Jan 6. Eur J Clin Microbiol Infect Dis. 2021. PMID 33404891 Free PMC article. Serological Assays for Assessing Postvaccination SARS-CoV-2 Antibody Response. Mahmoud SA, Ganesan S, Naik S, Bissar S, Zamel IA, Warren KN, Zaher WA, Khan G. Mahmoud SA, et al. Microbiol Spectr. 2021 Oct 31;92e0073321. doi Epub 2021 Sep 29. Microbiol Spectr. 2021. PMID 34585943 Free PMC article. Overview of Neutralization Assays and International Standard for Detecting SARS-CoV-2 Neutralizing Antibody. Liu KT, Han YJ, Wu GH, Huang KA, Huang PN. Liu KT, et al. Viruses. 2022 Jul 18;1471560. doi Viruses. 2022. PMID 35891540 Free PMC article. Review. Recent Developments in SARS-CoV-2 Neutralizing Antibody Detection Methods. Banga Ndzouboukou JL, Zhang YD, Fan XL. Banga Ndzouboukou JL, et al. Curr Med Sci. 2021 Dec;4161052-1064. doi Epub 2021 Dec 21. Curr Med Sci. 2021. PMID 34935114 Free PMC article. Review. Cited by Diagnostic performance of four lateral flow immunoassays for COVID-19 antibodies in Peruvian population. Calderon-Flores R, Caceres-Cardenas G, Alí K, De Vos M, Emperador D, Cáceres T, Eca A, Villa-Castillo L, Albertini A, Sacks JA, Ugarte-Gil C. Calderon-Flores R, et al. PLOS Glob Public Health. 2023 Jun 2;36e0001555. doi eCollection 2023. PLOS Glob Public Health. 2023. PMID 37267241 Free PMC article. Correlation of Postvaccination Fever With Specific Antibody Response to Severe Acute Respiratory Syndrome Coronavirus 2 BNT162b2 Booster and No Significant Influence of Antipyretic Medication. Tani N, Ikematsu H, Goto T, Gondo K, Inoue T, Yanagihara Y, Kurata Y, Oishi R, Minami J, Onozawa K, Nagano S, Kuwano H, Akashi K, Shimono N, Chong Y. Tani N, et al. Open Forum Infect Dis. 2022 Sep 23;910ofac493. doi eCollection 2022 Oct. Open Forum Infect Dis. 2022. PMID 36267253 Free PMC article. Current immunoassays and detection of antibodies elicited by Omicron SARS-CoV-2 infection. Migueres M, Chapuy-Regaud S, Miédougé M, Jamme T, Lougarre C, Da Silva I, Pucelle M, Staes L, Porcheron M, Diméglio C, Izopet J. Migueres M, et al. J Med Virol. 2023 Jan;951e28200. doi Epub 2022 Oct 17. J Med Virol. 2023. PMID 36207814 Free PMC article. SARS-CoV-2 anti-spike antibodies after a fourth dose of COVID-19 vaccine in adult solid-organ transplant recipients. Perrier Q, Lupo J, Gerster T, Augier C, Falque L, Rostaing L, Pelletier L, Bedouch P, Blanc M, Saint-Raymond C, Boignard A, Bonadona A, Noble J, Epaulard O. Perrier Q, et al. Vaccine. 2022 Oct 19;40446404-6411. doi Epub 2022 Sep 6. Vaccine. 2022. PMID 36184404 Free PMC article. Can the COVID-19 Pandemic Improve the Management of Solid Organ Transplant Recipients? Del Bello A, Marion O, Izopet J, Kamar N. Del Bello A, et al. Viruses. 2022 Aug 24;1491860. doi Viruses. 2022. PMID 36146666 Free PMC article. Review. 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J Clin Microbiol 58e00461-20. doi - DOI - PMC - PubMed Publication types MeSH terms Substances LinkOut - more resources Full Text Sources Atypon Europe PubMed Central PubMed Central Medical Genetic Alliance MedlinePlus Health Information Miscellaneous NCI CPTAC Assay Portal Estimates of SARS-CoV-2 Seroprevalence and Incidence of Primary SARS-CoV-2 Infections Among Blood Donors, by COVID-19 Vaccination Status — United States, April 2021–September 2022 Jefferson M. Jones, MD1; Irene Molina Manrique, MS2; Mars S. Stone, PhD3; Eduard Grebe, PhD3; Paula Saa, PhD4; Clara D. Germanio, PhD3; Bryan R. Spencer, PhD4; Edward Notari, MPH4; Marjorie Bravo, MD3; Marion C. Lanteri, PhD5; Valerie Green, MS5; Melissa Briggs-Hagen, MD1; Melissa M. Coughlin, PhD1; Susan L. Stramer, PhD4; Jean Opsomer, PhD2; Michael P. Busch, MD, PhD3 View author affiliations View suggested citationSummary What is already known about this topic? SARS-CoV-2 hybrid immunity immunity derived from both previous infection and vaccination has been reported to provide better protection than that from infection or vaccination alone. What is added by this report? By the third quarter of 2022, an estimated of persons aged ≥16 years in a longitudinal blood donor cohort had SARS-CoV-2 antibodies from previous infection or vaccination, including from infection alone and from vaccination alone; had hybrid immunity. Hybrid immunity prevalence was lowest among adults aged ≥65 years. What are the implications for public health practice? Low prevalence of infection-induced and hybrid immunity among older adults, who are at increased risk for severe disease if infected, reflects the success of public health infection prevention efforts while also highlighting the importance of this group staying up to date with recommended COVID-19 vaccination, including at least 1 bivalent dose. Altmetric Citations Views Views equals page views plus PDF downloads Changes in testing behaviors and reporting requirements have hampered the ability to estimate the SARS-CoV-2 incidence 1. Hybrid immunity immunity derived from both previous infection and vaccination has been reported to provide better protection than that from infection or vaccination alone 2. To estimate the incidence of infection and the prevalence of infection- or vaccination-induced antibodies or both, data from a nationwide, longitudinal cohort of blood donors were analyzed. During the second quarter of 2021 April–June, an estimated of persons aged ≥16 years had infection- or vaccination-induced SARS-CoV-2 antibodies, including from vaccination alone, from infection alone, and from both. By the third quarter of 2022 July–September, had SARS-CoV-2 antibodies from previous infection or vaccination, including from infection alone and from vaccination alone; had hybrid immunity. Prevalence of hybrid immunity was lowest among persons aged ≥65 years the group with the highest risk for severe disease if infected, and was highest among those aged 16–29 years Low prevalence of infection-induced and hybrid immunity among older adults reflects the success of public health infection prevention efforts while also highlighting the importance of older adults staying up to date with recommended COVID-19 vaccination, including at least 1 bivalent dose.*,† Since July 2020, SARS-CoV-2 seroprevalence in the United States has been estimated by testing blood donations 3. CDC, in collaboration with Vitalant, American Red Cross, Creative Testing Solutions, and Westat, established a nationwide cohort of 142,758 blood donors in July 2021; the cohort included persons who had donated blood two or more times in the preceding year.§ All blood donations collected during April–June 2021 were tested for antibodies against the spike S and nucleocapsid N proteins. Beginning in 2022, up to one blood donation sample per donor was randomly selected each quarter and tested using the Ortho VITROS SARS-CoV-2 Quantitative S immunoglobulin G¶ and total N antibody** tests. Both SARS-CoV-2 infection and COVID-19 vaccination result in production of anti-S antibodies, whereas anti-N antibodies only result from infection. At each donation, blood donors were asked if they had received a COVID-19 vaccine. Using vaccination history and results of antibody testing, the prevalence of the population aged ≥16 years with vaccine-induced, infection-induced, or hybrid immunity was estimated for four 3-month periods April–June 2021, January–March 2022, April–June 2022, and July–September 2022; in addition, the proportion of persons who transitioned from one immune status to another by quarter was estimated. Analysis was limited to 72,748 donors for whom it was possible to ascertain immune status during each period using their prior classification previously infected or vaccinated, antibody testing results, and their vaccination status at the time of each donation.†† The sample data were weighted to account for selection into the study cohort, for nonresponse during the four analysis periods, and for demographic differences between the blood donor population and the overall population. The weights were obtained through a combination of stratification and raking, an iterative weighting adjustment procedure 4. Rates of infection among those previously uninfected were estimated for each period by determining the percentage of anti-N–negative persons seroconverting to anti-N–positive from one 3-month period included in the study to the next. Estimates were stratified by age group 16–29, 30–49, 50–64, and ≥65 years and race and ethnicity§§ Asian, Black or African American [Black], White, Hispanic or Latino [Hispanic], and other. SAS version SAS Institute was used to compute the final weights, and R version R Foundation was used to calculate all the estimates and create the plots.¶¶ Seroprevalence and infection rates were estimated as weighted means and compared by demographic group and vaccination status using two-sided t-tests with a significance level of α = This activity was reviewed by CDC and conducted consistent with applicable federal law and CDC policy.*** During the first quarter examined April–June 2021, an estimated 95% CI = of persons aged ≥16 years had SARS-CoV-2 antibodies from previous infection or vaccination, including 95% CI = from vaccination alone, 95% CI = from infection alone, and 95% CI = from both Figure 1 Supplementary Figure 1, During January–March 2022, 95% CI = of persons aged ≥16 years had antibodies from previous infection or vaccination, including 95% CI = from vaccination alone, 95% CI = from infection alone, and 95% CI = from both. During July–September 2022, 95% CI = of persons had antibodies from previous infection or vaccination, including 95% CI = with vaccine-induced immunity alone, 95% CI = with infection-induced immunity alone, and 95% CI = with hybrid immunity. During July–September 2022, the prevalence of infection-induced immunity was 95% CI = among unvaccinated persons and 95% CI = among vaccinated persons. During July–September 2022, the lowest prevalence of hybrid immunity, 95% CI = was observed in persons aged ≥65 years, and the highest, 95% CI = in adolescents and young adults aged 16–29 years Figure 2 Supplementary Figure 2, During all periods, higher prevalences of hybrid immunity were observed among Black and Hispanic populations than among White and Asian populations Supplementary Figure 3, Among persons with no previous infection, the incidence of first infections during the study period conversion from anti-N–negative to anti-N–positive was higher among unvaccinated persons Table. From April–June 2021 through January–March 2022, the incidence of first SARS-CoV-2 infections among unvaccinated persons was compared with among vaccinated persons p< From January–March 2022 through April–June 2022, the incidence among unvaccinated persons was and was among vaccinated persons. Between April–June 2022 and July–September 2022, the incidence among unvaccinated persons was compared with among vaccinated persons p< Incidence of first SARS-CoV-2 infections was higher among younger than among older persons and was lower among Asian persons than among other racial and ethnic populations, but the differences among groups narrowed over time. Discussion Both infection-induced and hybrid immunity increased during the study period. By the third quarter of 2022, approximately two thirds of persons aged ≥16 years had been infected with SARS-CoV-2 and one half of all persons had hybrid immunity. Compared with vaccine effectiveness against any infection and against severe disease or hospitalization, the effectiveness of hybrid immunity against these outcomes has been shown to be higher and wane more slowly 2. This increase in seroprevalence, including hybrid immunity, is likely contributing to lower rates of severe disease and death from COVID-19 in 2022–2023 than during the early pandemic.††† The prevalence of hybrid immunity is lowest in adults aged ≥65 years, likely due to higher vaccination coverage and earlier availability of COVID-19 vaccines for this age group, as well as to higher prevalences of behavioral practices to avoid infection 5. However, lower prevalences of infection-induced and hybrid immunity could further increase the risk for severe disease in this group, highlighting the importance for adults aged ≥65 years to stay up to date with COVID-19 vaccination and have easy access to antiviral medications. COVID-19 vaccine efficacy studies have reported reduced effectiveness against SARS-CoV-2 infection during the Omicron-predominant period compared with earlier periods and have shown that protection against infection wanes more rapidly than does protection against severe disease 6,7. In this study, unvaccinated persons had higher rates of infection as evidenced by N antibody seroconversion than did vaccinated persons, indicating that vaccination provides some protection against infection. The differences in incidence could also be due to systematic differences between vaccinated and unvaccinated persons in terms of the prevalence of practicing prevention behaviors such as masking and physical distancing. The relative difference in infection rates narrowed during the most recent months, possibly because of waning of vaccine-induced protection against infection in the setting of increased time after vaccination or immune evasion by the SARS-CoV-2 Omicron variant. The narrowing of difference in infection rates might also be attributable to increasing similarities in behavior among vaccinated and unvaccinated persons during late 2022 8. The findings in this report are subject to at least six limitations. First, although COVID-19 booster vaccine doses and reinfections can strengthen immunity 9,10, this analysis did not account for these effects because blood donor vaccination history did not include the number of doses received, and data on reinfections were not captured. Second, immunity wanes over time, but time since vaccination or infection was not included in the analysis 2. Third, vaccination status was self-reported, potentially leading to misclassification. Fourth, although the results were adjusted based on differences in blood donor and general population demographics, estimates from blood donors might not be representative of the general population; thus, these results might not be generalizable. Fifth, vaccinated and unvaccinated persons might differ in other ways not captured by this analysis 8, nor can causality be inferred from the results on relative infection incidence. Finally, if both vaccination and infection occurred between blood donations included in the study, the order of occurrence could not be determined, and some unvaccinated donors might have been vaccinated before infection and thus misclassified; in 2022, this was uncommon and occurred in < of donors during any 3-month period. This report found that the incidence of first-time SARS-CoV-2 infection was lower among persons who had received COVID-19 vaccine than among unvaccinated persons and that infection-induced and hybrid immunity have increased but remain lowest in adults aged ≥65 years. These adults have consistently had a higher risk for severe disease compared with younger age groups, underscoring the importance of older adults staying up to date with recommended COVID-19 vaccination, including at least 1 bivalent dose. Acknowledgments Brad Biggerstaff, Matthew McCullough, CDC; Roberta Bruhn, Brian Custer, Xu Deng, Zhanna Kaidarova, Kathleen Kelly, Anh Nguyen, Graham Simmons, Hasan Sulaeman, Elaine Yu, Karla Zurita-Gutierrez, Vitalant Research Institute; Akintunde Akinseye, Jewel Bernard-Hunte, Robyn Ferg, Rebecca Fink, Caitlyn Floyd, Isaac Lartey, Sunitha Mathews, David Wright, Westat; Jamel Groves, James Haynes, David Krysztof, American Red Cross; Ralph Vassallo, Vitalant; Sherri Cyrus, Phillip Williamson, Creative Testing Solutions; Paul Contestable, QuidelOrtho; Steve Kleinman, University of British Columbia; CDC, Vitalant Research Institute, Westat, American Red Cross, and Creative Testing Solutions staff members; blood donors whose samples were analyzed and who responded to surveys for this study. Corresponding author Jefferson M. Jones, ioe8 Center for Immunization and Respiratory Diseases, CDC; 2Westat, Rockville, Maryland; 3Vitalant Research Institute, San Francisco, California; 4American Red Cross, Washington, DC; 5Creative Testing Solutions, Tempe, authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed. * † § Blood donors who donated at least twice during the year before July 2021 were included in the cohort, because they might represent persons who were more likely to donate frequently. Among donors who donated more than once during a quarter, one sample was selected at random for testing. ¶ ** †† §§ Persons of Hispanic origin might be of any race but are categorized as Hispanic; all racial groups are non-Hispanic. ¶¶ Jackknife replication was used to compute replicate weights. Weights were adjusted for nonresponse using adjustment cells created by age category, vaccination and previous infection status, and blood collection organization Vitalant or American Red Cross. Raking was used to further adjust the weights to account for demographic differences between the blood donor population and population. The demographic variables used for raking were sex female and male, age group 16–24, 25–34, 35–44, 45–54, 55–64, and ≥65 years, and race and ethnicity Asian, Black, White, Hispanic, and other. *** 45 part 46, 21 part 56; 42 Sect. 241d; 5 Sect. 552a; 44 Sect. 3501 et seq. ††† Accessed May 25, 2023. References Rader B, Gertz A, Iuliano AD, et al. Use of at-home COVID-19 tests—United States, August 23, 2021–March 12, 2022. MMWR Morb Mortal Wkly Rep 2022;71489–94. PMID35358168 Bobrovitz N, Ware H, Ma X, et al. Protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against the Omicron variant and severe disease a systematic review and meta-regression. Lancet Infect Dis 2023;23556–67. PMID36681084 Jones JM, Stone M, Sulaeman H, et al. Estimated US infection- and vaccine-induced SARS-CoV-2 seroprevalence based on blood donations, July 2020–May 2021. JAMA 2021;3261400–9. PMID34473201 Deville J-C, Särndal C-E, Sautory O. Generalized raking procedures in survey sampling. J Am Stat Assoc 1993;881013–20. Steele MK, Couture A, Reed C, et al. Estimated number of COVID-19 infections, hospitalizations, and deaths prevented among vaccinated persons in the US, December 2020 to September 2021. JAMA Netw Open 2022;5e2220385. PMID35793085 Higdon MM, Wahl B, Jones CB, et al. A systematic review of coronavirus disease 2019 vaccine efficacy and effectiveness against severe acute respiratory syndrome coronavirus 2 infection and disease. Open Forum Infect Dis 2022;9ofac138. PMID35611346 Feikin DR, Higdon MM, Abu-Raddad LJ, et al. Duration of effectiveness of vaccines against SARS-CoV-2 infection and COVID-19 disease results of a systematic review and meta-regression. Lancet 2022;399924–44. PMID35202601 Thorpe A, Fagerlin A, Drews FA, Shoemaker H, Scherer LD. Self-reported health behaviors and risk perceptions following the COVID-19 vaccination rollout in the USA an online survey study. Public Health 2022;20868–71. PMID35717747 Sette A, Crotty S. Immunological memory to SARS-CoV-2 infection and COVID-19 vaccines. Immunol Rev 2022;31027–46. PMID35733376 Atti A, Insalata F, Carr EJ, et al.; SIREN Study Group and the Crick COVID Immunity Pipeline Consortium. Antibody correlates of protection from SARS-CoV-2 reinfection prior to vaccination a nested case-control within the SIREN study. J Infect 2022;85545–56. PMID36089104 FIGURE 1. Prevalences of vaccine-induced, infection-induced, and hybrid* immunity† against SARS-CoV-2 among blood donors aged ≥16 years — United States, April 2021–September 2022 * Immunity derived from a combination of vaccination and infection. † Ascertained by the presence of anti-spike antibodies present in both COVID-19–vaccinated and SARS-CoV-2–infected persons and anti-nucleocapsid antibodies present only in previously infected persons and self-reported history of vaccination. FIGURE 2. Prevalences of vaccine-induced, infection-induced, and hybrid* immunity† against SARS-CoV-2 among blood donors aged ≥16 years, by age group — United States, April 2021–September 2022 * Immunity derived from a combination of vaccination and infection. † Ascertained by the presence of anti-spike antibodies present in both COVID-19–vaccinated and SARS-CoV-2–infected persons and anti-nucleocapsid antibodies present only in previously infected persons and self-reported history of vaccination. TABLE. Estimated percentage* of persons infected with SARS-CoV-2 for the first time among blood donors, by analysis quarter, sociodemographic characteristics, and vaccination status — United States, April 2021–September 2022 Characteristic Period, % 95% CI Apr–Jun 2021 to Jan–Mar 2022 Jan–Mar 2022 to Apr–Jun 2022 Apr–Jun 2022 to Jul–Sep 2022 Overall Total Unvaccinated Vaccinated Age group, yrs 16–29 Total Unvaccinated Vaccinated 30–49 Total Unvaccinated Vaccinated 50–64 Total Unvaccinated Vaccinated ≥65 Total Unvaccinated Vaccinated Race and ethnicity§ Asian Total Unvaccinated Vaccinated Black or African American Total Unvaccinated Vaccinated White Total Unvaccinated Vaccinated Hispanic or Latino Total Unvaccinated Vaccinated Other and multiple races¶ Total Unvaccinated Vaccinated * Percentage of uninfected persons anti-nucleocapsid–negative in the previous 3-month period seroconverting to anti-nucleocapsid–positive. If both vaccination and infection occurred between donations included in the study, the order could not be determined, and some unvaccinated donors might have been vaccinated before infection and thus misclassified. † If donors who transitioned from no antibodies to hybrid immunity between April–June 2021 and January–March 2022 were excluded, an estimated 95% CI = of unvaccinated donors were infected. For other periods, exclusion did not substantially change results. Between January–March and April–June 2022, of persons shifted from no antibodies to hybrid immunity. Between April–June and July–September 2022, of persons shifted from no antibodies to hybrid immunity. § Persons of Hispanic or Latino Hispanic origin might be of any race but are categorized as Hispanic; all racial groups are non-Hispanic. ¶ Includes American Indian or Alaska Native and non-Hispanic persons of other races. Suggested citation for this article Jones JM, Manrique IM, Stone MS, et al. Estimates of SARS-CoV-2 Seroprevalence and Incidence of Primary SARS-CoV-2 Infections Among Blood Donors, by COVID-19 Vaccination Status — United States, April 2021–September 2022. MMWR Morb Mortal Wkly Rep 2023;72601–605. DOI MMWR and Morbidity and Mortality Weekly Report are service marks of the Department of Health and Human Services. Use of trade names and commercial sources is for identification only and does not imply endorsement by the Department of Health and Human Services. References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication. All HTML versions of MMWR articles are generated from final proofs through an automated process. This conversion might result in character translation or format errors in the HTML version. Users are referred to the electronic PDF version and/or the original MMWR paper copy for printable versions of official text, figures, and tables. Questions or messages regarding errors in formatting should be addressed to mmwrq The development timeline of COVID-19 vaccines is unprecedented, with more than 300 vaccine developers active worldwide. Vaccine candidates developed with various technology platforms targeting different epitopes of SARS-CoV-2 are in the pipeline. Vaccine developers are using a range of immunoassays with different readouts to measure immune responses after vaccination, making comparisons of the immunogenicity of different COVID-19 vaccine candidates April, 2020, in a joint effort, the Coalition for Epidemic Preparedness Innovations CEPI, the National Institute for Biological Standards and Control NIBSC, and WHO provided vaccine developers and the entire scientific community with a research reagent for an anti-SARS-CoV-2 antibody. The availability of this material was crucial for facilitating the development of diagnostics, vaccines, and therapeutic preparations. This effort was an initial response when NIBSC, in its capacity as a WHO collaborating centre, was working on the preparation of the WHO International Standards. This work included a collaborative study that was launched in July, 2020, to test serum samples and plasma samples sourced from convalescent patients with the aim of selecting the most suitable candidate material for the WHO International Standards for anti-SARS-CoV-2 immunoglobulin. The study involved 44 laboratories from 15 countries and the use of live and pseudotype-based neutralisation assays, ELISA, rapid tests, and other methods. The outcomes of the study were submitted to WHO in November, 2020. The inter-laboratory variation was reduced more than 50 times for neutralisation and 2000 times for ELISA when assay values were reported relative to the International International Standard and International Reference Panel for anti-SARS-CoV-2 immunoglobulins were adopted by the WHO Expert Committee on Biological Standardization on Dec 10, WHO International Standard for anti-SARS-CoV-2 Scholar The International Standard allows the accurate calibration of assays to an arbitrary unit, thereby reducing inter-laboratory variation and creating a common language for reporting data. The International Standard is based on pooled human plasma from convalescent patients, which is lyophilised in ampoules, with an assigned unit of 250 international units IU per ampoule for neutralising activity. For binding assays, a unit of 1000 binding antibody units BAU per mL can be used to assist the comparison of assays detecting the same class of immunoglobulins with the same specificity eg, anti-receptor-binding domain IgG, anti-N IgM, etc The International Standard is available in the NIBSC have been launched for the harmonisation of immune response assessment across COVID-19 vaccine candidates, including the CEPI Global Centralised Laboratory for Epidemic Preparedness InnovationsCEPI establishes global network of laboratories to centralise assessment of COVID-19 vaccine Scholar CEPI centralised laboratories will achieve harmonisation of the results from different vaccine clinical trials with the use of common standard operating procedures and the same crucial reagents, including a working standard calibrated to the international basic tool for any harmonisation is the global use of an International Standard and IU to which assay data need to be calibrated with the use of a reliable method. It is therefore crucial that the International Standard is properly used by all vaccine developers, national reference laboratories, and academic groups worldwide, and that immunogenicity results are reported as an international standard unit IU/mL for neutralising antibodies and BAU/mL for binding assay formats.In this manner, the results from clinical trials expressed in IU would allow for the comparison of the immune responses after natural infection and induced by various vaccine candidates. This comparison is particularly important for the identification of correlates of protection against COVID-19; should neutralising antibodies be further supported as a component of the protective response, the expression of antibody responses in IU/mL is essential to gather a consensus from several clinical trials and other studies on the titre required for the correlate of protection against SARS-2-CoV has not yet been unequivocally defined, antibodies are likely to be at least part of the protective response. The effect of new variants on the evaluation of antibodies is obvious and unequivocal comparisons are required. Reporting the immunological responses from vaccine clinical trials against the International Standard is essential for the evaluation of clinical data submitted to national regulatory authorities as well as to WHO for emergency use listing, especially as placebo-controlled efficacy studies become operationally unfeasible. There will be a substantial effect on the use of the International Standard if regulatory authorities worldwide request data in IU/mL or BAU/mL. We also encourage journal editors and peer reviewers to ensure that the international standard is used as the benchmark in publications and that data from serology assays are reported in International Standard declare no competing TT Cramer JP Chen R Mayhew S Evolution of the COVID-19 vaccine development Rev Drug Discov. 2020; 19 WHO International Standard for anti-SARS-CoV-2 for Epidemic Preparedness InnovationsCEPI establishes global network of laboratories to centralise assessment of COVID-19 vaccine infoPublication historyPublished March 23, 2021IdentificationDOI Copyright © 2021 Published by Elsevier Ltd. All rights this article on ScienceDirectView Large ImageDownload Hi-res image Download .PPT

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