Accuracy of Rapid Point-of-Care Antibody Test in patients with suspected or confirmed COVID-19

AbstractObjectivesTo 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.

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Assessment of the Field Utility of a Rapid Point-of-Care Test for SARS-CoV-2 Antibodies in a Household Cohort

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.21-0592 ◽

2021 ◽

Author(s):

Mehal Churiwal ◽

Kelly D. Lin ◽

Salman Khan ◽

Srijana Chhetri ◽

Meredith S. Muller ◽

...

Keyword(s):

Cohort Study ◽

Confidence Interval ◽

Point Of Care ◽

Natural Infection ◽

Field Performance ◽

Antibody Test ◽

Asymptomatic Infection ◽

Point Of Care Test ◽

Antibody Tests ◽

Rapid Antibody

Point-of-care (POC) tests to detect SARS-CoV-2 antibodies offer quick assessment of serostatus after natural infection or vaccination. We compared the field performance of the BioMedomics COVID-19 IgM/IgG Rapid Antibody Test against an ELISA in 303 participants enrolled in a SARS-CoV-2 household cohort study. The rapid antibody test was easily implemented with consistent interpretation across 14 users in a variety of field settings. Compared with ELISA, detection of seroconversion lagged by 5 to 10 days. However, it retained a sensitivity of 90% (160/177, 95% confidence interval [CI] 85–94%) and specificity of 100% (43/43, 95% CI 92–100%) for those tested 3 to 5 weeks after symptom onset. Sensitivity was diminished among those with asymptomatic infection (74% [14/19], 95% CI 49–91%) and early in infection (45% [29/64], 95% CI 33–58%). When used appropriately, rapid antibody tests offer a convenient way to detect symptomatic infections during convalescence.

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Combined point of care SARS-CoV-2 nucleic acid and antibody testing in suspected moderate to severe COVID-19 disease

10.1101/2020.06.16.20133157 ◽

2020 ◽

Author(s):

Petra Mlcochova ◽

Dami Collier ◽

Allyson Ritchie ◽

Sonny M. Assennato ◽

Myra Hosmillo ◽

...

Keyword(s):

Nucleic Acid ◽

Diagnostic Tests ◽

Point Of Care ◽

Standard Laboratory ◽

Reference Standard ◽

Rt Pcr ◽

A Genome ◽

Antibody Tests ◽

Composite Reference Standard

AbstractBackgroundRapid COVID-19 diagnosis in hospital is essential for patient management and identification of infectious patients to limit the potential for nosocomial transmission. The diagnosis of infection is complicated by 30-50% of COVID-19 hospital admissions with nose/throat swabs testing negative for SARS-CoV-2 nucleic acid, frequently after the first week of illness when SARS-CoV-2 antibody responses become detectable. We assessed the diagnostic accuracy of combined rapid antibody point of care (POC) and nucleic acid assays for suspected COVID-19 disease in the emergency department.MethodsWe developed (i) an in vitro neutralization assay using a lentivirus expressing a genome encoding luciferase and pseudotyped with spike (S) protein and (ii) an ELISA test to detect IgG antibodies to nucleocapsid (N) and S proteins from SARS-CoV-2. We tested two lateral flow rapid fingerprick tests with bands for IgG and IgM. We then prospectively recruited participants with suspected moderate to severe COVID-19 and tested for SARS-CoV-2 nucleic acid in a combined nasal/throat swab using the standard laboratory RT-PCR and a validated rapid POC nucleic acid amplification (NAAT) test. Additionally, serum collected at admission was retrospectively tested by in vitro neutralisation, ELISA and the candidate POC antibody tests. We evaluated the performance of the individual and combined rapid POC diagnostic tests against a composite reference standard of neutralisation and standard laboratory based RT-PCR.Results45 participants had specimens tested for nucleic acid in nose/throat swabs as well as stored sera for antibodies. Using the composite reference standard, prevalence of COVID-19 disease was 53.3% (24/45). Median age was 73.5 (IQR 54.0-86.5) years in those with COVID-19 disease by our composite reference standard and 63.0 (IQR 41.0-72.0) years in those without disease. The overall detection rate against the composite reference standard was 79.2% (95CI 57.8-92.9%) for rapid NAAT, decreasing from 100% (95% CI 65.3-98.6%) in days 1-4 to 50.0% (95% CI 11.8-88.2) for days 9-28 post symptom onset. Correct identification of COVID-19 with combined rapid POC diagnostic tests was 100% (95CI 85.8-100%) with a false positive rate of 5.3-14.3%, driven by POC LFA antibody tests.ConclusionsCombined POC tests have the potential to transform our management of COVID-19, including inflammatory manifestations later in disease where nucleic acid test results are negative. A rapid combined approach will also aid recruitment into clinical trials and in prescribing therapeutics, particularly where potentially harmful immune modulators (including steroids) are used.

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The QuantuMDx Q-POC SARS-CoV-2 RT-PCR assay for rapid detection of COVID-19 at point-of-care: preliminary evaluation of a novel technology

10.1101/2021.07.12.21260119 ◽

2021 ◽

Author(s):

Jessica Caffry ◽

Matthew Selby ◽

Katie Barr ◽

George Morgan ◽

David McGurk ◽

...

Keyword(s):

Point Of Care ◽

Reference Laboratory ◽

Preliminary Evaluation ◽

Rt Pcr ◽

Reference Test ◽

Pcr Assay ◽

Current Standard ◽

Primary Analysis ◽

Point Of Care Test ◽

Control And Management

Background: Accurate, affordable, and rapid point-of-care (PoC) diagnostics are critical to the global control and management of the COVID-19 pandemic. The current standard for accurate diagnosis of SARS-CoV-2 is laboratory-based reverse transcription polymerase chain reaction (RT-PCR). Here, we report a preliminary prospective performance evaluation of the QuantuMDx Q-POC SARS CoV-2 RT-PCR assay. Methods: Between November 2020 and March 2021, we obtained 49 longitudinal nose and throat swabs from 29 individuals hospitalised with RT-PCR confirmed COVID-19 at St Georges' NHS Foundation Trust, London (UK). In addition, we obtained 101 mid nasal swabs from healthy volunteers in June 2021. We then used these samples to evaluate the Q-POC SARS-CoV-2 RT-PCR assay. The primary analysis was to compare the sensitivity and specificity of the Q-POC test against a reference laboratory-based RT-PCR assay. Results: The overall sensitivity of the Q-POC test compared with the reference test was 96.88% (83.78%- 99.92% CI) for a cycle threshold (Ct) cut-off value for the reference test of 35 and 80.00% (64.35% to 90.95% CI) without altering the reference test's Ct cut-off value of 40. Conclusions: The Q-POC test is a sensitive, specific and rapid point-of-care test for SARS-CoV-2 at a reference Ct cut-off value of 35. The Q-POC test provides an accurate and afforda-ble option for RT-PCR at point-of-care without the need for sample pre-processing and laboratory handling. The Q-POC test would enable rapid diagnosis and clinical triage in acute care and other settings.

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Seroprevalence study of SARS-CoV-2 infection in General Practice in Ireland

BJGP Open ◽

10.3399/bjgpo.2021.0038 ◽

2021 ◽

pp. BJGPO.2021.0038

Author(s):

Michael Edmund O'Callaghan ◽

Elizabeth Ryan ◽

Cathal Walsh ◽

Peter Hayes ◽

Monica Casey ◽

...

Keyword(s):

General Practice ◽

Average Length ◽

Point Of Care ◽

Antibody Test ◽

Igg Antibodies ◽

Antibody Testing ◽

Igg Antibody ◽

Seroprevalence Study ◽

History Of ◽

Pcr Test

Background: SARS-CoV-2 antibody testing in community settings may help us better understand the immune response to this virus and therefore help guide public health efforts. Aim: Conduct a seroprevalence study of IgG antibodies in Irish GP clinics. Design and Setting: Participants were 172 staff and 799 patients of 15 general practices in the Midwest region of Ireland. Methods: This seroprevalence study utilised 2 manufacturers’ point-of-care (POC) SARS-CoV-2 IgM-IgG combined antibody tests, offered to patients and staff in general practice from mid-June to mid-July 2020. Results: Immunoglobulin G (IgG) seroprevalence was 12.6% in patients attending general practice and 11.1% in staff working in general practice, with administrative staff having the lowest seroprevalence at 2.5% and nursing staff having the highest at 17.6%. Previous symptoms suggestive of SARS-CoV-2 and history of a polymerase chain reaction (PCR) test were associated with higher seroprevalence. IgG antibodies were detected in approximately 80% of participants who had a previous PCR-confirmed infection. Average length of time between participants’ positive PCR test and positive IgG antibody test was 83 days. Conclusion: Patients and healthcare staff in general practice in Ireland had relatively high rates of IgG to SARS-CoV-2 compared to the national average at the time (1.7%). Four-fifths of participants with a history of confirmed COVID-19 disease still had detectable antibodies an average of 12 weeks post-infection. While not proof of immunity, SARS-CoV-2 POC testing can be used to estimate IgG seroprevalence in general practice settings.

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Clinical validation of a point-of-care antibody test for COVID-19

10.1101/2020.12.16.20248303 ◽

2020 ◽

Author(s):

Monila Patel ◽

Yogesh Lakhotia ◽

Sneha Shah ◽

Nilay Suthar ◽

Cherry Shah ◽

...

Keyword(s):

Confidence Interval ◽

Sensitivity And Specificity ◽

Significant Role ◽

Point Of Care ◽

Antibody Test ◽

Lateral Flow ◽

Clinical Validation ◽

Rt Pcr ◽

Antibody Tests ◽

Spike Proteins

AbstractThe objective of this study was to evaluate the performance of a lateral flow antibody test for COVID-19, approved for use in India. Although many point-of-care antibody tests are available globally, they have been subjected to limited clinical validation. This has led to suboptimal outcomes in the field, where antibody tests play a significant role in tracking the immunity of individuals and communities. In this study an antibody test, ImmunoQuick that recognizes antibodies to the Nucleocapsid and Spike proteins of SARS CoV-2 was tested in 100 symptomatic patients with a positive or negative diagnosis of COVID-19, based on RT-PCR results. The overall sensitivity of the test was found to be 86.1% (95% CI: 76.4% to 92.8%) and specificity 100% (95% confidence interval: 73.5% to 100%). The sensitivity reached a peak of 95.7% with samples taken 17 days after the onset of symptoms. Overall, the sensitivity and specificity of the test are sufficient for assessing seroprevalence.

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Development of a rapid antibody test for point-of-care diagnosis of animal African trypanosomosis

Veterinary Parasitology ◽

10.1016/j.vetpar.2016.11.017 ◽

2017 ◽

Vol 233 ◽

pp. 32-38 ◽

Cited By ~ 13

Author(s):

Alain Boulangé ◽

Davita Pillay ◽

Cyrille Chevtzoff ◽

Nicolas Biteau ◽

Vanessa Comé de Graça ◽

...

Keyword(s):

Point Of Care ◽

Antibody Test ◽

Rapid Antibody

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Evaluation of a Point-of-Care Test for Pre-Vaccination Testing to Detect Antibodies against Canine Adenoviruses in Dogs

Viruses ◽

10.3390/v13020183 ◽

2021 ◽

Vol 13 (2) ◽

pp. 183

Author(s):

Michèle Bergmann ◽

Mike Holzheu ◽

Yury Zablotski ◽

Stephanie Speck ◽

Uwe Truyen ◽

...

Keyword(s):

Predictive Value ◽

Neutralizing Antibodies ◽

Immune Status ◽

Point Of Care ◽

Reference Standard ◽

Antibody Testing ◽

Point Of Care Test ◽

Specific Pathogen ◽

Privately Owned ◽

Positive Results

(1) Background: Antibody testing is commonly used to assess a dog’s immune status. For detection of antibodies against canine adenoviruses (CAVs), one point-of-care (POC) test is available. This study assessed the POC test´s performance. (2) Methods: Sera of 198 privately owned dogs and 40 specific pathogen-free (SPF) dogs were included. The reference standard for detection of anti-CAV antibodies was virus neutralization (VN) using CAV-1 and CAV-2 antigens. Specificity, sensitivity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy (OA) of the POC test were assessed. Specificity was considered most important. (3) Results: Prevalence of CAV-1 neutralizing antibodies (≥10) was 76% (182/238) in all dogs, 92% (182/198) in the subgroup of privately owned dogs, and 0% (0/40) in SPF dogs. Prevalence of CAV-2 neutralizing antibodies (≥10) was 76% (181/238) in all dogs, 91% (181/198) in privately owned dogs, and 0% (0/40) in SPF dogs. Specificity for detection of CAV-1 antibodies was lower (overall dogs, 88%; privately owned dogs, 56%; SPF dogs, 100%) compared with specificity for detection of CAV-2 antibodies (overall dogs, 90%; privately owned dogs, 65%; SPF dogs, 100%). (4) Conclusions: Since false positive results will lead to potentially unprotected dogs not being vaccinated, specificity should be improved to reliably detect anti-CAV antibodies that prevent infectious canine hepatitis in dogs.

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The Use of Antigenic SARS-CoV-2 Point-of-Care Test: The Italian Pediatric Real-Life Experience

Clinical Pediatrics ◽

10.1177/00099228211053916 ◽

2021 ◽

pp. 000992282110539

Author(s):

Federica Ferrari ◽

Fortunata Civitelli ◽

Francesca Ardenti Morini ◽

Federico Angelo Carmelo Buonaiuto ◽

Gianluca Frega ◽

...

Keyword(s):

Life Experience ◽

Close Contact ◽

Point Of Care ◽

Pediatric Population ◽

Real Life ◽

Gastrointestinal Symptoms ◽

Point Of Care Test ◽

Large Numbers ◽

History Of ◽

Acute Rhinitis

In Italy, during the second epidemic wave of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rapid antigenic (Ag) test at point-of-care (POCT) station were employed to quickly evaluate large numbers of swabs. We collected data of all children who underwent the Ag test in our hospital. All positive patients were recalled to perform reverse transcription polymerase chain reaction. A total of 2133 tests were collected over 1 month. Clinical data of 1941 children (median age = 3.7 years) were analyzed: 1343 (69.2%) patients complained of symptoms, 594 (30.6%) had a history of close contact with SARS-CoV-2-positive individuals. Among symptoms reported, acute rhinitis was the most frequent (67.9%), followed by cough (42.6%) and fever (31.5%). Among all tests, 95.8% resulted negative, 4.2% positive: 37/89 were confirmed. In confirmed cases, fever (56.2% vs 32.2%; P = .041) and gastrointestinal symptoms (18.8% vs 6.25%; P = .041) were significantly more frequent compared with negative children. The use of POCT for Ag test seems appropriate for SARS-CoV-2 screening in the pediatric population. In children, fever and gastrointestinal symptoms may constitute red flags of SARS-CoV-2.

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Antibody seroprevalence and rate of asymptomatic infections with SARS-CoV-2 in Austrian hospital personnel

10.1101/2021.02.01.21250898 ◽

2021 ◽

Author(s):

Iris Leister ◽

Elisabeth Ponocny-Seliger ◽

Herwig Kollaritsch ◽

Peter Dungel ◽

Barbara Holzer ◽

...

Keyword(s):

Antibody Test ◽

World Health ◽

Antibody Concentration ◽

Study Cohort ◽

Living Situation ◽

Rehabilitation Facilities ◽

Specific Igg ◽

Antibody Tests ◽

Time Point ◽

Rapid Antibody

AbstractContextOn March 11, the World Health Organization (WHO) announced the current corona virus disease 2019 (COVID-19) outbreak as a pandemic. The first laboratory-confirmed case of COVID-19 in Austria was announced on February 27, 2020. Since then, the incidence of infection followed an exponential increase until a complete lockdown in March 2020. Thereafter easing of restrictions was gradually introduced and until mid-August daily infections remained mostly below 5 per 100.000 population.ObjectivesThe aims of this study are to determine i) how many employees in Austrian trauma hospitals and rehabilitation facilities have virus specific IgG and IgM, and/or neutralizing antibodies against SARS-CoV-2, ii) how many are active virus carriers (symptomatic and asymptomatic) during the study, iii) the antibody decline in seropositive subjects over a period of around six months, and iv) the utility of rapid antibody tests for outpatient screening.Study DesignOpen uncontrolled observational cross-sectional study.Setting/ParticipantsA total of 3301 employees in 11 Austrian trauma hospitals and rehabilitation facilities of the Austrian Social Insurance for Occupational Risks (AUVA) participated in the study.Study Interventions and MeasuresRapid antibody tests for SARS-CoV-2 specific IgG and IgM antibodies, and RT-PCR tests based on oropharyngeal swab samples, as well as laboratory-based antibody tests using ELISA/PRNT were performed. The tests were conducted twice, with an interval of 42.4±7.7 (Min=30, Max=64) days. Additionally, participants filled out a questionnaire including questions related to personal health, traveling activities, living situation, as well as inquiries of symptoms and comorbidities. Antibody positive tested participants were re-tested with ELISA/PRNT tests at a third time point on average 188.0±12.8 days after their initial test.ResultsIn our study cohort, only 27 out of 3301 participants (0.81%) had a positive antibody test at any time point during the study confirmed via neutralization test. Among participants who had positive test results in either of the antibody tests, 50.4% did not report any symptoms consistent with common manifestations of COVID-19 during the study period or within the preceding six weeks. In the group who tested positive during or prior to study inclusion the most common symptoms of an acute viral illness were rhinitis (21.9%), and loss of taste and olfactory sense (21.9%).The rapid antibody test was generally more sensitive based on serum (sensitivity=86.6%) as compared to whole blood (sensitivity=65.4). Concerning both ELISA tests overall the Roche test detected 24 (sensitivity=88.9%) and the Diasorin test 22 positive participants (sensitivity=81.5%).In participants with a positive PRNT, a significant decrease in PRNT concentration from 31.8±22.9 (Md=32.0) at T1 to 26.1±17.6 (Md=21.3) at T2 to 21.4±13.4 (Md=16.0) at T3 (χ2=23.848, df=2, p<0.001) was observed (χ2=23.848, df=2, p<0.001) – with an average time of 42.4±7.7 days between T1 and T2 and 146.9±13.8 days between T2 and T3.ConclusionsDuring the study period (May 11th – December 21th) only 0.81% were tested positive for antibodies in our study cohort. The antibody concentration decreases significantly over time with 14.8% (4 out of 27) losing detectable antibodies.

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Cohen’s kappa statistics as a convenient means to identify accurate SARS-CoV-2 rapid antibody tests

10.1101/2020.06.13.20130070 ◽

2020 ◽

Author(s):

Harukazu Iseki

Keyword(s):

Symptom Onset ◽

The Body ◽

Kappa Statistics ◽

List Type ◽

Rt Pcr ◽

Convenient Means ◽

Antibody Tests ◽

Level Of Agreement ◽

Rapid Antibody ◽

Elisa Data

AbstractThere are many available rapid antibody tests, but the performance of such tests remains unclear. Moreover, it is difficult to compare among the various devices regarding their sensitivity & specificity.In order to compare the performance of such devices, we used Cohen’ kappa statistics to assess the level of agreement between RT-PCR and rapid antibody tests. In doing this study, we considered the term of validity after symptom-onset to compare two tests. It takes more than a week to produce antibodies in the body, and RT-PCR thus gives negative result in the convalescent period. On ELISA data from the literature kappa statistics was calculated as 1.0 beyond 10 days after symptom-onset. By taking these factors into consideration, we evaluated agreement with samples collected beyond 10 days of symptom-onset during the active period.We calculated the data from 9 devices, and the kappa statistics for English data were calculated as 0.64 on average. The same finding was 0.75 for Chinese data. These results corresponded with the values from sensitivity & specificity of their reports. Both reports had no details about the collection procedures. Kappa statistics might become even more accurate, if samples could be restricted to ones collected beyond 10 days. Regarding the data from our hospital’, the kappa statistics was 0.97 when restricted to samples collected beyond 10 days, which thus showed excellent agreement.By using kappa statistics, the performances of rapid antibody tests can be shown as one figure, so that their comparison becomes easy to carry out.Highlights▪Using kappa statistics, agreement between PCR and ELISA was perfect from the data beyond 10 days of symptom-onset.▪The results of kappa statistics corresponded with the values from sensitivity & specificity of the English and the Chinese literatures.▪Kappa statistics was calculated as 0.97 from the data beyond 10 days of symptom-onset, and sensitivity & specificity were 95.2% and 100% in our hospital.▪Kappa statistics is a convenient means to identify accurate rapid antibody tests.

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