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Highlights • Rapid antibody test was 100% sensitive detecting 42/42 SARS-CoV-2 positive samples. • SARS-CoV-2 Rapid Antibody Test was 96.86% (155/159) specific at 10 min. readout time. • Cold-like-symptom samples had no cross-reactivity with the Rapid Antibody Test., Objectives The true prevalence and seropositivity of SARS-CoV-2 infection remains unknown, due to the number of asymptomatic infections and limited access to high-performance antibody tests. To fill this gap, the clinical performance of a point-of-care SARS-CoV-2 Rapid Antibody Assay, a chromatographic immunoassay for detection of IgM/IgG antibodies, in near-patient settings was assessed. Methods 42 Anti-SARS-Cov-2 positive (CoV+) and 92 Anti-SARS-Covid-2 negative (CoV-) leftover samples from before December 2019 were assessed, using the Elecsys® Anti-SARS-CoV-2 as the reference assay. Analytical specificity was tested using leftover samples collected before December 2019 from patients with common cold symptoms. Results The SARS-CoV-2 Rapid Antibody Test was 100.0% (95% CI 91.59–100.00) sensitive and 96.74% (95% CI 90.77–99.32) specific, with 0.00% assay failure rate. No cross-reactivity was observed against the common cold panel. Method comparison was additionally conducted by two external laboratories, using 100 CoV+/275 CoV- samples, also comparing whole blood versus plasma matrix. The comparison demonstrated 96.00% positive/96.36% negative percent agreement for plasma with the Elecsys Anti-SARS-CoV-2 and 99.20% percent overall agreement between whole blood and EDTA plasma. Conclusion The SARS-CoV-2 Rapid Antibody Test demonstrated similar performance to the manufacturer’s data and a centralized automated immunoassay, with no cross-reactivity with common cold panels.

Objective: We aimed to use SARS-CoV-2 antibody tests to assess the asymptomatic seroprevalence of individuals in high-risk hospital cohorts who's previous COVID-19 exposure is unknown; staff, and patients requiring haemodialysis or chemotherapy after the first wave.Methods: In a single Center, study participants had five SARS-CoV-2 antibody tests done simultaneously; one rapid diagnostic test (RDT) (Superbio Colloidal Gold IgM/IgG), and four laboratory tests (Roche Elecsys® Anti-SARS-CoV-2 IgG [RE], Abbott Architect i2000SR IgG [AAr], Abbott Alinity IgG [AAl], and Abbott Architect IgM CMIA). To determine seroprevalence, only positive test results on laboratory assay were considered true positives.Results: There were 157 participants, of whom 103 (65.6%) were female with a median age of 50 years (range 19–90). The IgG component of the RDT showed a high number of false positives (n = 18), was inferior to the laboratory assays (p < 0.001 RDT vs. AAl/AAr, p < 0.001 RDT vs. RE), and had reduced specificity (85.5% vs. AAl/AAr, 87.2% vs. RE). Sero-concordance was 97.5% between IgG laboratory assays (RE vs. AAl/AAr). Specificity of the IgM component of the RDT compared to Abbott IgM CMIA was 95.4%. Ten participants had positivity in at least one laboratory assay, seven (9.9%) of which were seen in HCWs. Two (4.1%) hematology/oncology (H/O) patients and a single (2.7%) haemodialysis (HD) were asymptomatically seropositive. Asymptomatic seroprevalence of HCWs compared to patients was not significant (p = 0.105).Conclusion: HCWs (9.9%) had higher, although non-significant asymptomatic seroprevalence of SARS-CoV-2 antibodies compared to high-risk patients (H/O 4.1%, HD 2.7%). An IgM/IgG rapid diagnostic test was inferior to laboratory assays. Sero-concordance of 97.5% was found between IgG laboratory assays, RE vs. AAl/AAr.

Objetivo: Determinar la positividad y los patrones de los resultados positivos de las pruebas rápidas de anticuerpos contra el SARS-CoV-2 en los pacientes atendidos en un Servicio de Emergencia. Materiales y métodos: Evaluación retrospectiva de las pruebas rápidas de anticuerpos contra el SARS-CoV-2 aplicadas durante el mes de junio/2020 en el Servicio de Emergencia del Hospital EsSalud G. Almenara, Lima, Perú. Resultados: Fueron evaluadas 1 805 pruebas realizadas en igual número de pacientes. En 864 (48%) de las pruebas fueron positivas, en el siguiente orden: patrón combinado de IgM-IgG en 635 (73%), IgM en 134 (16%) y, finalmente, de IgG en 95 (11%). Conclusiones: La positividad de las pruebas rápidas de anticuerpos contra el SARS-CoV-2 fue de 48%, y el patrón combinado de IgM-IgG fue el más frecuente, en tres cuartas partes de los casos confirmados. Objective: To determine the positivity and patterns of positive results of rapid antibody tests against SARS-CoV-2 in patients attending to an Emergency Service. Material and methods: Retrospective evaluation of the rapid antibody tests against SARS-CoV-2 applied during the month of June 2020 in the Emergency Service of the Hospital EsSalud G.Almenara, Lima, Peru. Results: We included 1805 tests performed on the same number of patients. In 864 (48%) of the tests were positive, in the following order: combined IgM-IgG pattern in 635 (73%), IgM in 134 (16%) and finally IgG in 95 (11%). Conclusions: The positivity of the rapid antibody tests against SARS-CoV-2 was 48%, and the combined pattern of IgM-IgG was the most frequent in three quarters of the confirmed cases.

ObjectivesTo assess the real-world diagnostic accuracy of the Livzon point-of-care rapid test for antibodies to SARS-COV-2DesignProspective cohort studySettingDistrict general hospital in EnglandParticipants173 Patients and 224 hospital staff with a history of COVID-19 symptoms, and who underwent PCR and/or reference antibody testing for COVID-19.InterventionsThe Livzon point-of-care (POC) lateral flow immunoassay rapid antibody test (IgM and IgG) was conducted at least 7 days after onset of symptoms and compared to the composite reference standard of PCR for SARS-COV-2 plus reference laboratory testing for antibodies to SARS-COV-2. The SARS-CoV-2 RT-PCR was tested using the available molecular technology during the study time (PHE laboratories, GeneXpert®system Xpert, Xpress SARS-CoV-2 and Source bioscience laboratory). All molecular platforms/assays were PHE/NHSE approved. The reference antibody test was the Elecsys Anti-SARS-CoV-2 assay (Roche diagnostics GmBH).Main outcome measuresSensitivity and specificity of the rapid antibody testResultsThe reference antibody test was positive in 190/268 (70.9%) of participants with a history of symptoms suggestive of COVID-19; in the majority (n=312) the POC test was taken 35 days or more after onset of symptoms. The POC antibody test had an overall sensitivity of 90.1% (292/328, 95% CI 86.3 – 93.1) and specificity of 100% (68/68, 95% CI 94.7 - 100) for confirming prior SARS-CoV-2 infection when compared to the composite reference standard. Sensitivity was 97.8% (89/92, 95% CI 92.3% to 99.7%) in participants who had been admitted to hospital and 84.4% (124/147, 95% CI 77.5% to 89.8%) in those with milder illness who had never been seen in hospital.ConclusionsThe Livzon point-of-care antibody test had comparable sensitivity and specificity to the reference laboratory antibody test, so could be used in clinical settings to support decision-making about patients presenting with more than 10 days of symptoms of COVID-19.What is already known on this topic-Presence of IgG and IgM antibodies to SARS-COV-2 indicates that the person was infected at least 7 days previously and is usually no longer infectious.-Rapid point-of-care tests for antibodies to SARS-COV-2 are widely available, cheap and easy to use-Preliminary evaluations suggested that rapid antibody tests may have insufficient accuracy to be useful for testing individual patients.What this study adds-The rapid point-of-care test for antibodies to SARS-COV-2 was 90.1% sensitive and 100% specific compared to reference standards for prior infection with COVID-19.-This is comparable to reference antibody tests-The point-of-care test evaluated in this study could be used to support clinical decision-making in real time, for patients presenting with symptoms of possible COVID-19 with at least 10 days of symptoms.

BACKGROUND Although the detection of viral particles by reverse transcription polymerase chain reaction (RT-PCR) is the gold standard diagnostic test for coronavirus disease 2019 (COVID-19), the false-negative results constitute a big challenge. AIM To examine a group of patients diagnosed and treated as possible COVID-19 pneumonia whose multiple nasopharyngeal swab samples were negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by RT-PCR but then serological immunoglobulin M/immunoglobulin G (IgM/IgG) antibody against SARS-CoV-2 were detected by rapid antibody test. METHODS Eighty possible COVID-19 patients who had at least two negative consecutive COVID-19 RT-PCR test and were subjected to serological rapid antibody test were evaluated in this study. RESULTS The specific serological total IgM/IgG antibody against SARS-CoV-2 was detected in twenty-two patients. The mean age of this patient group was 63.2± 13.1-years-old with a male/female ratio of 11/11. Cough was the most common symptom (90.9%). The most common presenting chest computed tomography findings were bilateral ground glass opacities (77.2%) and alveolar consolidations (50.1%). The mean duration of time from appearance of first symptoms to hospital admission, to hospital admission, to treatment duration and to serological positivity were 8.6 d, 11.2 d, 7.9 d, and 24 d, respectively. Compared with reference laboratory values, serologically positive patients have shown increased levels of acute phase reactants, such as C-reactive protein, ferritin, and procalcitonin and higher inflammatory markers, such as erythrocyte sedimentation rate, lactate dehydrogenase enzyme, and fibrin end-products, such as D-dimer. A left shift on white blood cell differential was observed with increased neutrophil counts and decreased lymphocytes. CONCLUSION Our study demonstrated the feasibility of a COVID-19 diagnosis based on rapid antibody test in the cases of patients whose RT-PCR samples were negative. Detection of antibodies against SARS-CoV-2 with rapid antibody test should be included in the diagnostic algorithm in patients with possible COVID-19 pneumonia. © The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved. 2-s2.0-85116515535

The ongoing coronavirus disease 2019 (COVID-19) epidemic has made a huge impact on health, economies, and societies all over the world. Although reverse transcription-polymerase chain reaction (RT-PCR)-based nucleic acid detection has been primarily used in the diagnosis of COVID-19, it is time-consuming with limited application scenarios and must be operated by qualified personnel. Antibody test, particularly point-of-care antibody testing, is a suitable complement to nucleic acid test as it provides rapid, portable, and cost-effective detection of infections. In this study, a Rapid Antibody Test Kit was developed based on fluorescence immunochromatography for the sensitive, accurate, and automated detection of immunoglobulin M (IgM) and IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human serum, plasma, and whole blood samples within 10 min. The sensitivity, specificity, precision, and stability of the test kit were of good performance. No cross-activity and no interference was observed. In the multiple-center parallel study, 223 samples from hospitalized patients were used to evaluate the clinical specificity of the test. Both SARS-CoV-2 IgM and IgG achieved a clinical specificity of 98.21%. The clinical sensitivities of SARS-CoV-2 IgM and IgG were 79.54% and 87.45%, respectively, among 733 reverse transcription-polymerase chain reaction (RT-PCR) confirmed SARS-CoV-2 samples. For the combined IgM and IgG assays, the sensitivity and specificity were 89.22% and 96.86%, respectively. Our results demonstrate that the combined use of IgM and IgG could serve as a more suitable alternative detection method for patients with COVID-19, and the developed kit is of great public health significance for the prevention and control of the COVID-19 pandemic.

Objective:This study aims to assess the effectivity of a rapid antibody test on detecting the occupational exposure in healthcare professionals who have been working in a pandemic hospital since the initial cases were seen in our country.Methods:Prevention of Coronavirus disease 2019 (COVID-19) in our institution was managed according to the Republic of Turkey (T.C.) Ministry of Health recommendations. Between 20.04.2020 and 05.05.2020, 376 high-risk professionals (triage, emergency room, COVID-19 outpatient unit, COVID-19 clinic and intensive care unit) were screened by rapid antibody test for COVID-19. Positive cases were retrospectively examined in terms of COVID-19 diagnosis or potential symptoms of COVID-19 infection (fever, perspiration, debility, cough, myalgia, sour throat, nasal flow, diarrhea, loss of smell/taste sensation).Results:The mean age was 32.7±8.9 years, 222 patients were female and 154 were male. Positive rapid antibody test was detected in 27 (7.2%) patients: 24 of those had COVID-19 diagnosis or potential symptoms of COVID-19 infection, where 3 patients had no signs or symptoms of the disease.Conclusion:During pandemic, the reliability of rapid antibody tests has become under question due to validation issues. However, rapid antibody test may be feasible for COVID-19 screening among healthcare professionals in order to assess the precautions and prevent nosocomial infection.