Evaluation of serological lateral flow assays for severe acute respiratory syndrome coronavirus-2

Abstract

Background COVID-19 has resulted in significant morbidity and mortality worldwide. Lateral flow assays can detect anti-Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) antibodies to monitor transmission. However, standardized evaluation of their accuracy and tools to aid in interpreting results are needed. Methods We evaluated 20 IgG and IgM assays selected from available tests in April 2020. We evaluated the assays’ performance using 56 pre-pandemic negative and 56 SARS-CoV-2-positive plasma samples, collected 10–40 days after symptom onset, confirmed by a molecular test and analyzed by an ultra-sensitive immunoassay. Finally, we developed a user-friendly web app to extrapolate the positive predictive values based on their accuracy and local prevalence. Results Combined IgG + IgM sensitivities ranged from 33.9 to 94.6%, while combined specificities ranged from 92.6 to 100%. The highest sensitivities were detected in Lumiquick for IgG (98.2%), BioHit for both IgM (96.4%), and combined IgG + IgM sensitivity (94.6%). Furthermore, 11 LFAs and 8 LFAs showed perfect specificity for IgG and IgM, respectively, with 15 LFAs showing perfect combined IgG + IgM specificity. Lumiquick had the lowest estimated limit-of-detection (LOD) (0.1 μg/mL), followed by a similar LOD of 1.5 μg/mL for CareHealth, Cellex, KHB, and Vivachek. Conclusion We provide a public resource of the accuracy of select lateral flow assays with potential for home testing. The cost-effectiveness, scalable manufacturing process, and suitability for self-testing makes LFAs an attractive option for monitoring disease prevalence and assessing vaccine responsiveness. Our web tool provides an easy-to-use interface to demonstrate the impact of prevalence and test accuracy on the positive predictive values.

Longitudinal profile of antibody response to SARS-CoV-2 in patients with COVID-19 in a setting from Sub–Saharan Africa: A prospective longitudinal study

“…Furthermore, positivity rate for the assay Cellex IgM was found to be very low in this study, which is similar to previous report [ 30 ]. In contrast, others have reported higher positivity rate, ranging between 55.4% and 87.5% [ 22 , 31 ]. The differences between the studies might be attributed to differences in sampling time, clinical severity status and study population immune responses.…”

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“… 13 , 20 Serological tests cannot be used to diagnose acute or active COVID-19 infection. 31 , 40 , 41 The performance characteristics of such tests are assessed based on their clinical sensitivity and specificity using a 95% confidence interval. The sensitivity or the true positive rate (TPR) is evaluated based on the ability of the test to identify the samples with antibodies to SARS-CoV-2.…”

COVID-19 Amongst Travelers at Points of Entry in Nepal: Screening, Testing, Diagnosis and Isolation Practices

“…Although the gold standard for the diagnosis of SARS-CoV-2 is detection of viral RNA through nucleic acid amplification and real time polymerase chain reaction (RT-PCR), the LFA test is a reasonable alternative because it is inexpensive, widely available, easy to use and provides results in 15-30 min [5]. The LFA test has high specificity, approaching 100% in some studies, but sensitivity is much lower and crucially dependent on viral load [6,7]. While cases can therefore be missed, this does mean, however, that the LFA test is likely to identify people with COVID-19 who have high viral loads, who, in turn, are those most likely to transmit infection to others.…”