Study of the cellular and humoral immune responses to SARS-CoV-2 vaccination.

Our understanding of cellular immunity in response to COVID-19 infection or vaccination is limited because of less commonly used techniques. We investigated both the cellular and humoral immune responses before and after the administration of a third dose of the SARS-CoV-2 vaccine among a group of healthcare workers. Cellular immunity was evaluated using the VIDAS interferon-gamma (IFNγ) RUO test, which enables automated measurement of IFNγ levels after stimulating peripheral blood lymphocytes. Booster doses significantly enhanced both cellular and humoral immunity. Concerning cellular response, the booster dose increased the percentage of positive IFNγ release assay (IGRA) results but no difference in IFNγ release was found. The cellular response was not associated with protection against SARS-CoV-2 infection. Interestingly, vaccinated and infected healthcare workers exhibited the highest levels of anti-spike and neutralizing antibodies. In conclusion, the IGRA is a simple method for measuring cellular immune responses after vaccination. However, its usefulness as a complement to the study of humoral responses is yet to be demonstrated in future research.

Evaluation of two anti-SARS-CoV-2 antibody immunoassays for monitoring patients on pre-exposure prophylaxis.

Pre-exposure prophylaxis (PrEP) is crucial to prevent severe COVID-19 in immunocompromised patients. A reliable method is needed to quantify anti-SARS-CoV-2 antibody levels for personalized monitoring during PrEP. We measured the binding antibody concentrations of 63 immunocompromised patients receiving 300mg or 600mg tixagevimab/cilgavimab on PrEP day and twice during the following 3 months. All blood samples were tested using the Abbott anti-SARS-CoV-2 IgG II Quant assay, the Roche Elecsys anti-SARS-CoV-2 S assay, and live virus-based neutralization assays. The results of the two immunoassays were correlated on day 0, 1 month, and 3 months post-PrEP. Passing-Bablok regression demonstrated higher anti-S concentration values measured with the Roche immunoassay compared to those measured with the Abbott immunoassay. Antibody concentrations were higher after 600 mg tixagevimab/cilgavimab prophylaxis than after 300 mg. The neutralizing antibody titers obtained using the omicron BA.5 and BA.2.75 strains were low. Both automated immunoassays are suitable for monitoring immunocompromised patients on PrEP.

Comparison of Estetrol Exposure between Women and Mice to Model Preclinical Experiments and Anticipate Human Treatment.

Estetrol (E4) is a natural estrogen with promising therapeutic applications in humans. The European Medicines Agency and the Food and Drug Administration have approved the use of 15 mg E4/3 mg drospirenone for contraceptive indication. Phase III clinical trials with 15-20 mg E4 for the relief of climacteric complaints are currently running. Relevant data from preclinical animal models are needed to characterize the molecular mechanisms and the pharmacological effects of E4 and possibly to reveal new therapeutic applications and to anticipate potential adverse effects. Therefore, it is important to design experimental procedures in rodents that closely mimic or anticipate human E4 exposure. In this study, we compared the effects of E4 exposure after acute or chronic administration in women and mice. Women who received chronic E4 treatment per os at a dose of 15 mg once daily reached a steady state within 6 to 8 days, with a mean plasma concentration of 3.20 ng/mL. Importantly, with subcutaneous, intraperitoneal or oral administration of E4 in mice, a stable concentration over time that would mimic human pharmacokinetics could not be achieved. The use of osmotic minipumps continuously releasing E4 for several weeks provided an exposure profile mimicking chronic oral administration in women. Measurements of the circulating concentration of E4 in mice revealed that the mouse equivalent dose necessary to mimic human treatment does not fit with the allometric prediction. In conclusion, this study highlights the importance of precise definition of the most appropriate dose and route of administration to utilize when developing predictive preclinical animal models to mimic or anticipate specific human treatment.

Weaker Effects of the Fourth Dose of BNT162b2 SARS-CoV-2 Vaccine on the Elderly Human Population.

The vaccines presently available are less effective in older people due to senescence of their immune systems. We measured the antibody responses of 42 adults living in nursing homes after the third and the fourth doses of an mRNA vaccine and found that the strain (BA.2 and BA.2.75: from 64 to 128, BA.5: from 16 to 32, BQ.1.1: from 16 to 64 among the uninfected) influenced the effect of the fourth dose of vaccine on neutralizing antibodies. The fourth dose also increased binding antibodies (from 1036 BAU/mL to 5371 BAU/mL among the uninfected, from 3700 BAU/mL to 6773 BAU/mL among the BA.5 infected). This effect was less significant than that of the third dose of vaccine for both neutralizing (BA.2: from 8 to 128, BA.5: from 2 to 16, BA.2.75: from 8 to 64, BQ.1.1: from 2 to 16) and binding antibodies (from 139.8 BAU/mL to 2293 BAU/mL). However, the fourth dose attained the 5000 BAU/mL threshold conferring approximately 80% protection against a SARS-CoV-2 BA.2 infection in most individuals, unlike the third.

Family Refusal of Heart Valve Donation.

BACKGROUND: Impairment of the heart valves can occur due to many diseases that cause deterioration of the contractile function and harm the body, making it necessary for the heart valves to be transplanted. This study's objective was to analyze families' refusal to donate heart valves between 2001 and 2020. METHODS: This was a cross-sectional study conducted in accordance with the Terms of Family Authorization for Donation of Organs and Tissues from patients diagnosed with brain death by an Organ Procurement Organization in the state of São Paulo. The variables analyzed were sex, age, cause of death, hospital type (private or public), and refusal to donate heart valves. Data analysis was performed using Stata software version 15.0  (StataCorp, LLC, College Station, Tex, United States) in a descriptive and inferential way. RESULTS: A total of 236 people (9.65%) refused to specifically donate heart valves of their relatives, the majority of whom were between 41 and 59 years old. Most potential donors had suffered a stroke and had been in a private hospital. From 2001 to 2009, there was a decreasing trend in males and the age group from 0 to 11 years old, whereas there was an increasing trend in those aged 60 years or older and in the general population. Between 2010 and 2020, there was a downward trend in the 41- to 59-year-old age group and the general population. CONCLUSIONS: The specific refusal to donate heart valves was associated with age, diagnosis, and whether the institution was public or private.

Self-Care Requisites for People with Intestinal Ostomies: A Scoping Review / Requisitos de autocuidado para pessoas com estomias intestinais: revisão de escopo / Requisitos de autocuidado a personas con ostomías intestinales: revisión de alcance

Self-care is one of the main factors altered in the life of a person with an ostomy. Self-care requisites with nursing support are necessary. Objectives: To map the self-care requisites for people with intestinal ostomies in their adaptive process, guided by Orem's theory. Materials and methodology: A scoping review was conducted between May and June 2022, in which studies published from 2000 to 2022 were selected, based on Orem's self-care deficit nursing theory. The sources of evidence used were Medical Literature Analysis and Retrieval System Online, Cinahl, Scopus, Latin American and Caribbean Health Sciences Literature, Nursing database, Índice Bibliográfico Español en Ciencias de la Salud, Web of Science, Scientific Electronic Library Online, Brazilian Digital Library of Theses and Dissertations, Open Access Scientific Repositories of Portugal, Theses Canada, DART-Europe E-Theses Portal, and National ETD Portal. Studies presenting at least one requisite of self-care for people with intestinal ostomies, whether or not they addressed Orem's theory, and that were published in full were included. We followed the recommendations of the Joanna Briggs Institute and the PRISMA International Guide, registered in the Open Science Framework (10.17605/OSF.IO/XRH5K). The following descriptors and search strategies were used: (ostomy OR colostomy OR ileostomy OR stoma) AND (self-care OR self-management) AND (adaptation OR adjustment). Results: The final sample was composed of 87 studies. In universal requisites, studies in the category "nutritional aspects" predominated, of which the most frequent was "eat regularly and follow a balanced diet" (23; 26.4%); in developmental requisites, the prevalent category was "stoma and peristomal skin care" and requisite "assess peristomal skin integrity" (27; 31.0%); in the health deviation requisites, the predominant category was "choice of collection equipment and adjuvant products" and the requisite "use hydrocolloid powder to absorb moisture in cases of dermatitis" (13; 14.9%). Conclusions: The study contributes to guiding the assistance to the person with an ostomy, improving the self-care learning process. However, new intervention studies are still needed.

O autocuidado é um dos principais fatores alterados na vida da pessoa com estomia. Requisitos de autocuidado com o apoio da enfermagem são necessários. Objetivos: mapear os requisitos de autocuidado para pessoas com estomia intestinal em seu processo adaptativo, norteado pela teoria de Orem. Materiais e método: revisão de escopo realizada entre maio e junho de 2022, na qual foram selecionados estudos publicados de 2000 a 2022, com base no referencial da teoria de enfermagem do déficit do autocuidado de Orem. Utilizaram-se como fontes de evidência Medical Literature Analysis and Retrieval System Online, Cinahl, Scopus, Literatura Latino-Americana e do Caribe em Ciências da Saúde, Base de dados em Enfermagem, Índice Bibliográfico Español en Ciencias de la Salud, Web of Science, Scientific Electronic Library Online, Biblioteca Digital Brasileira de Teses e Dissertações, Repositório Científico de Acesso Aberto de Portugal, Theses Canada, DART-Europe E-Theses Portal e National ETD Portal. Incluíram-se estudos que apresentassem pelo menos um requisito de autocuidado para pessoas com estomias intestinais, que abordassem ou não a teoria de Orem e publicados na íntegra. Seguiram-se as recomendações da Joanna Briggs Institute e do Prisma International Guide, com registro na Open Science Framework (10.17605/OSF.IO/XRH5K). Usaram-se os seguintes descritores e estratégias de busca: (ostomy OR colostomy OR ileostomy OR stoma) AND (self care OR self-management) AND (adaptation OR adjustment). Resultados: a amostra final foi composta de 87 estudos. Nos requisitos universais, predominaram estudos na categoria "aspectos nutricionais", dos quais o mais frequente foi "comer regularmente e seguir uma dieta equilibrada" (23; 26,4 %); nos requisitos de desenvolvimento, a categoria prevalente foi "cuidados com a estomia e a pele periestomal" e o requisito, "avaliar a integridade da pele periestomal" (27; 31,0 %); nos requisitos de desvio de saúde, a categoria predominante foi "escolha do equipamento coletor e dos produtos adjuvantes", e o requisito, "usar pó hidrocoloide para absorver a umidade em casos de dermatite" (13; 14,9 %). Conclusões: o estudo contribui para nortear a assistência à pessoa com estomia, melhorando o processo de aprendizado do autocuidado. Contudo, novos estudos de intervenção ainda são necessários.

El autocuidado es uno de los principales factores en la vida de la persona con ostomía. Requisitos de autocuidado con el soporte de la enfermería son necesarios. Objetivos: mapear los requisitos de autocuidado a personas con ostomía intestinal en su proceso adaptativo, norteado por la teoría de Orem. Materiales y método: revisión de alcance llevada a cabo entre mayo y junio de 2022, en la que se seleccionaron estudios publicados de 2000 a 2022, desde el marco de la teoría de enfermería del déficit del autocuidado de Orem. Se emplearon como fuentes de evidencia Medical Literature Analysis and Retrieval System Online, Cinahl, Scopus, Literatura Latinoamericana y del Caribe en Ciencias de la Salud, Base de datos en Enfermería, Índice Bibliográfico Español en Ciencias de la Salud, Web of Science, Scientific Electronic Library Online, Biblioteca Digital Brasileira de Teses e Dissertações, Repositório Científico de Acesso Aberto de Portugal, Theses Canada, DART-Europe E-Theses Portal y National ETD Portal. Se incluyeron estudios que presentaran al menos un requisito de autocuidado a personas con ostomías intestinales, que abordaran o no la teoría de Orem y publicados en la íntegra. Se siguieron las recomendaciones de Joanna Briggs Institute y Prisma International Guide, con registro en la Open Science Framework (10.17605/OSF.IO/XRH5K). Se emplearon los siguientes descriptores y estrategias de búsqueda: (ostomy OR colostomy OR ileostomy OR stoma) AND (self care OR self-management) AND (adaptation OR adjustment). Resultados: la muestra final fue de 87 estudios. En los requisitos universales, predominaron estudios en la categoría "aspectos nutricionales", de los cuales el más frecuente fue "comer regularmente y seguir una dieta balanceada" (23; 26,4 %); en los requisitos de desarrollo, la categoría prevalente fue "cuidados con la ostomía y la piel periestomal" y el requisito, "evaluar la integridad de la piel periestomal" (27; 31,0 %); en los requisitos de desviación de la salud, la categoría predominante fue "selección del equipo recolector y los productos adyuvantes", y el requisito, "usar polvo hidrocoloide para absorber la humidad en casos de dermatitis" (13; 14,9 %). Conclusiones: el estudio aporta a la orientación de la atención a la persona con ostomía, lo que puede mejorar el proceso de aprendizaje del autocuidado. Sin embargo, nuevos estudios de intervención aún son necesarios.

The + 3010/C single nucleotide polymorphism (rs1710) at the HLA-G 3' untranslated region is associated with a short transcript exhibiting a deletion of 92 nucleotides.

The physiological expression of HLA-G is mainly observed in the placenta, playing an essential role in maternal-fetal tolerance. Among the HLA-G mRNA alternative transcripts, the one lacking 92 bases at the HLA-G 3' untranslated region (3'UTR), the 92bDel transcript, is more stable, is associated with increased HLA-G soluble levels, and was observed in individuals presenting a 14 bp insertion (14 bp+) at the 3'UTR. We investigated the presence of the 92bDel transcript in placenta samples, correlating its expression levels with the HLA-G polymorphisms at the 3'UTR. The 14 bp+ allele correlates with the presence of the 92bDel transcript. However, the polymorphism triggering this alternative splicing is the + 3010/C allele (rs1710, allele C). Most 14 bp+ haplotypes (UTR-2/-5/-7) present allele + 3010/C. However, 14 bp- haplotypes such as UTR-3 are also associated with + 3010/C, and the 92bDel transcript can be detected in homozygous samples for the 14 bp- allele carrying at least one copy of UTR-3. The UTR-3 haplotype is associated with alleles G*01:04 and the HLA-G lineage HG0104, which is a high-expressing lineage. The only HLA-G lineage that is not likely to produce this transcript is HG010101, associated with the + 3010/G allele. This functional difference may be advantageous, considering the high worldwide frequency of the HG010101 lineage. Therefore, HLA-G lineages are functionally distinct regarding the 92bDel transcript expression, and the 3010/C allele triggers the alternative splicing that produces this shorter and more stable transcript.

Effects of the Quality of Life on the Adaptation of People With An Intestinal Stoma.

The study aimed to examine the effects of the quality of life on the adaptation of people with an intestinal stoma. Cross-sectional study with 152 people with an ostomy. Three instruments were used: the sociodemographic and clinical characterization, Scale for the Level of Adaptation of Ostomy Patients, and City of Hope Quality of Life - Ostomy Questionnaire. The multiple linear regression model, multivariate technique, and cluster were used. The determination coefficient showed that 94.1% of the variability of the Adaptation scores is explained by the dimensions of quality of life. It can be seen that the highest standardized coefficients are the psychological dimension (ß = .386) and the social dimension (ß = .365), in which they produce the greatest changes in the average adaptation scores. The psychological and social well-being dimensions are the ones that most contribute to raising the levels of adaptation.

Current immunoassays and detection of antibodies elicited by Omicron SARS-CoV-2 infection.

The present study aimed to determine whether current commercial immunoassays are adequate for detecting anti-Omicron antibodies. We analyzed the anti-SARS-CoV-2 antibody response of 23 unvaccinated individuals 1-2 months after an Omicron infection. All blood samples were tested with a live virus neutralization assay using a clinical Omicron BA.1 strain and four commercial SARS-CoV-2 immunoassays. We assessed three anti-Spike immunoassays (SARS-CoV-2 IgG II Quant [Abbott S], Wantaï anti-SARS-CoV-2 antibody ELISA [Wantaï], Elecsys Anti-SARS-CoV-2 S assay [Roche]) and one anti-Nucleocapsid immunoassay (Abbott SARS-CoV-2 IgG assay [Abbott N]). Omicron neutralizing antibodies were detected in all samples with the live virus neutralization assay. The detection rate of the Abbott S, Wantai, Roche, and Abbott N immunoassays were 65.2%, 69.6%, 86.9%, and 91.3%, respectively. The sensitivities of Abbott S and Wantai immunoassays were significantly lower than that of the live virus neutralization assay (p = 0.004, p = 0.009; Fisher's exact test). Antibody concentrations obtained with anti-S immunoassays were correlated with Omicron neutralizing antibody concentrations. These data provide clinical evidence of the loss of performance of some commercial immunoassays to detect antibodies elicited by Omicron infections. It highlights the need to optimize these assays by adapting antigens to the circulating SARS-CoV-2 strains.

Antibody Titers and Protection against Omicron (BA.1 and BA.2) SARS-CoV-2 Infection.

The emergence of the SARS-CoV-2 variants of concern has greatly influenced the immune correlates of protection, and there are little data about the antibody threshold concentrations to protect against infection with SARS-CoV-2 Omicron BA.1 or BA.2. We analyzed the antibody responses of 259 vaccinated healthcare workers, some of whom had been previously infected by SARS-CoV-2. The median follow-up was 179 days (IQR: 171-182) after blood collection. We detected 88 SARS-CoV-2 Omicron infections during the follow-up period, 55 (62.5%) with SARS-CoV-2 BA.1, and 33 (37.5%) with SARS-CoV-2 BA.2. A neutralizing antibody titer below 8 provided no protection against a BA.1 infection, a titer of 16 or 32 gave 73.2% protection, and a titer of 64 or 128 provided 78.4% protection. Conversely, the BA.2 infection rate did not vary as a function of anti-BA.2 neutralizing antibody titers. Binding antibody concentrations below 6000 BAU/mL provided no protection against Omicron BA.1 infection, 6000-20,000 BAU/mL provided 55.6% protection, and 20,000 or more provided 87.7% protection. There was no difference in BA.2 infection depending on the binding antibody concentration. Further studies are needed to investigate the relationship between antibody concentrations and infection with the Omicron BA.4/5 variants that are becoming predominant worldwide.

Decreased Efficiency of Neutralizing Antibodies from Previously Infected or Vaccinated Individuals against the B.1.617.2 (Delta) SARS-CoV-2 Variant.

The neutralizing antibody response is a key component of adaptive immunity and a primary protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The increased transmissibility of the SARS-CoV-2 Delta variant and its capacity to cause more severe disease could be linked to a significant reduction in neutralizing antibodies generated during a previous infection or vaccination. We analyzed blood samples from 162 unvaccinated health care workers (HCWs) collected 1 to 3 months postinfection and from 263 vaccinated health care workers 1 month after the last injection. We have compared the neutralizing antibody titers obtained using two virus strains, B.1.160 and B.1.617.2 (Delta variant). Binding antibody concentrations were measured by an immunoassay. The median neutralizing antibody titer against the B.1.160 strain was 128 (interquartile range [IQR], 16 to 256) and 32 (IQR, 8 to 128) against the Delta variant. To obtain a neutralizing antibody titer of 32 or 64, a binding antibody concentration of 182 binding antibody units (BAU)/mL (IQR, 81 to 974) was required with the strain B.1.160, while a concentration of 2,595 BAU/mL (IQR, 1,176 to 5,353) was required with the Delta variant. Our data indicate that antibodies neutralize the SARS-CoV-2 Delta variant 4 times less efficiently than they neutralize an earlier strain. Half of the HCWs had decreased protection from 94% to 76.8% or less for the same total antibody concentration. But neutralization might be correlated with other immune responses. The contributions of other responses, such as those of the T cell and B cell systems, to protection require further investigation. IMPORTANCE Recent studies showed that the neutralizing antibody titer is an important contributor to protection against SARS-CoV-2. With the emergence of new variants, the question arises of maintaining the neutralizing capacities of vaccines and/or of a past infection. We had protective data associated with total antibody concentrations and neutralizing antibody titers for a B.1.160 strain. We showed that to maintain the same levels of protection and, therefore, the same levels of neutralizing antibodies, a total antibody concentration 8.5 times greater is required with the Delta strain. (This study has been registered at ClinicalTrials.gov under registration no. NCT04385108.).

Global Impact of the COVID-19 Pandemic on Cerebral Venous Thrombosis and Mortality.

BACKGROUND AND PURPOSE: Recent studies suggested an increased incidence of cerebral venous thrombosis (CVT) during the coronavirus disease 2019 (COVID-19) pandemic. We evaluated the volume of CVT hospitalization and in-hospital mortality during the 1st year of the COVID-19 pandemic compared to the preceding year. METHODS: We conducted a cross-sectional retrospective study of 171 stroke centers from 49 countries. We recorded COVID-19 admission volumes, CVT hospitalization, and CVT in-hospital mortality from January 1, 2019, to May 31, 2021. CVT diagnoses were identified by International Classification of Disease-10 (ICD-10) codes or stroke databases. We additionally sought to compare the same metrics in the first 5 months of 2021 compared to the corresponding months in 2019 and 2020 (ClinicalTrials.gov Identifier: NCT04934020). RESULTS: There were 2,313 CVT admissions across the 1-year pre-pandemic (2019) and pandemic year (2020); no differences in CVT volume or CVT mortality were observed. During the first 5 months of 2021, there was an increase in CVT volumes compared to 2019 (27.5%; 95% confidence interval [CI], 24.2 to 32.0; P<0.0001) and 2020 (41.4%; 95% CI, 37.0 to 46.0; P<0.0001). A COVID-19 diagnosis was present in 7.6% (132/1,738) of CVT hospitalizations. CVT was present in 0.04% (103/292,080) of COVID-19 hospitalizations. During the first pandemic year, CVT mortality was higher in patients who were COVID positive compared to COVID negative patients (8/53 [15.0%] vs. 41/910 [4.5%], P=0.004). There was an increase in CVT mortality during the first 5 months of pandemic years 2020 and 2021 compared to the first 5 months of the pre-pandemic year 2019 (2019 vs. 2020: 2.26% vs. 4.74%, P=0.05; 2019 vs. 2021: 2.26% vs. 4.99%, P=0.03). In the first 5 months of 2021, there were 26 cases of vaccine-induced immune thrombotic thrombocytopenia (VITT), resulting in six deaths. CONCLUSIONS: During the 1st year of the COVID-19 pandemic, CVT hospitalization volume and CVT in-hospital mortality did not change compared to the prior year. COVID-19 diagnosis was associated with higher CVT in-hospital mortality. During the first 5 months of 2021, there was an increase in CVT hospitalization volume and increase in CVT-related mortality, partially attributable to VITT.

Understanding of Brazilian Nursing Assistants and Technicians of Brain Death.

BACKGROUND: Brain death (BD) is defined as the total and irreversible cessation of brain functions including the brain stem. The team that assists the patient in this situation is made up of higher-level and technical health professionals. Our objective was to analyze the understanding of nursing assistants and technicians of BD. METHODS: Descriptive and exploratory research with a qualitative approach was carried out with nursing assistants and technicians who were members of the Regional Nursing Council of São Paulo, Brazil. After collection, the data were submitted to the thematic-category content analysis technique. RESULTS: From the analysis, the following categories emerged: an understanding of BD; religiosity and hope in the reversal of BD; and "brain death associated with the possibility of organ donation." CONCLUSIONS: This study reinforces the need to train professionals at a technical nursing level on the subject in order to improve nursing care and avoid mistaken beliefs that can negatively influence the process of donating organs and tissues for transplantation.

Influence of the Delta Variant and Vaccination on the SARS-CoV-2 Viral Load.

Studies comparing SARS-CoV-2 nasopharyngeal (NP) viral load (VL) according to virus variant and host vaccination status have yielded inconsistent results. We conducted a single center prospective study between July and September 2021 at the drive-through testing center of the Toulouse University Hospital. We compared the NP VL of 3775 patients infected by the Delta (n = 3637) and Alpha (n = 138) variants, respectively. Patient's symptoms and vaccination status (2619 unvaccinated, 636 one dose and 520 two doses) were recorded. SARS-CoV-2 RNA testing and variant screening were assessed by using Thermo Fisher® TaqPath™ COVID-19 and ID solutions® ID™ SARS-CoV-2/VOC evolution Pentaplex assays. Delta SARS-CoV-2 infections were associated with higher VL than Alpha (coef = 0.68; p ≤ 0.01) independently of patient's vaccination status, symptoms, age and sex. This difference was higher for patients diagnosed late after symptom onset (coef = 0.88; p = 0.01) than for those diagnosed early (coef = 0.43; p = 0.03). Infections in vaccinated patients were associated with lower VL (coef = -0.18; p ≤ 0.01) independently of virus variant, symptom, age and sex. Our results suggest that Delta infections could lead to higher VL and for a longer period compared to Alpha infections. By effectively reducing the NP VL, vaccination could allow for limiting viral spread, even with the Delta variant.

Evaluation of Three Quantitative Anti-SARS-CoV-2 Antibody Immunoassays.

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 1.3 and 7, respectively. The results of the 3 immunoassays were significantly globally pairwise correlated and for late infection sera (P < 0.001). They were correlated for recent infection sera measured with Alinity and Liaison (P < 0.001). 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 B1.160 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.