Evaluation of 32 rapid tests for detection of antibodies against SARS-CoV-2.

AIMS: To evaluate the analytical performance of 32 rapid tests for detection of antibodies against coronavirus SARS-CoV-2. MATERIALS AND METHODS: We used at total of 262 serum samples (197 pre-pandemic and 65 convalescent COVID-19), and three criteria to evaluate the rapid tests under standardized and optimal conditions: (i) Immunoglobulin G (IgG) specificity "good" if lower limit of the 95% confidence interval was ≥ 97.0%, "acceptable" if point estimate was ≥ 97.0%, otherwise "not acceptable". (ii) IgG sensitivity "good" if point estimate was ≥ 90.0%, "acceptable" if ≥ 85.0%, otherwise "not acceptable". (iii) User-friendliness "not acceptable" if complicated to perform or difficult to read result, otherwise "good". We also included partial evaluations of three automated immunoassay systems. RESULTS: Sensitivity and specificity varied considerably; IgG specificity between 90.9% (85.9-94.2) and 100% (97.7-100.0), and IgG sensitivity between 53.8% (41.9-65.4) and 98.5% (91.0-100.0). Combining our evaluation criteria, none of the 28 rapid tests that detected IgG had an overall performance considered "good", seven tests were considered "acceptable", while 21 tests were considered "not acceptable". Four tests detected only total antibodies and were not given an overall evaluation. IgG sensitivity and/or specificity of the automated immunoassays did not exceed that of many rapid tests. CONCLUSION: When prevalence is low, the most important analytical property is a test's IgG specificity, which must be high to minimize false positive results. Out of 32 rapid tests, none had a performance classified as "good", but seven were classified as "acceptable".

Evaluation of eleven rapid tests for detection of antibodies against SARS-CoV-2.

Objectives: SARS-CoV-2, causing COVID-19, has emerged to cause a human pandemic. Detection of SARS-CoV-2 in respiratory samples by using PCR is the standard laboratory diagnostic tool. Our aim was to perform a limited evaluation of the diagnostic performance and user-friendliness of eleven rapid tests for detection of antibodies against SARS-CoV-2. Methods: All participants were tested with PCR against SARS-CoV-2 at a clinical microbiology laboratory. Comparing with results from PCR tests, we evaluated the rapid tests' performances in three arms; 1) 20 hospitalized patients with PCR-confirmed COVID-19, 2) 23 recovered outpatients with former PCR-confirmed COVID-19, and 3) 49 participants with suspected COVID-19 presenting at a primary care emergency room. Results: All eleven tests detected antibodies in hospitalized COVID-19 patients, though with varying sensitivities. In former outpatients recovered from COVID-19, there were differences between tests in the immunoglobulin type G (IgG) sensitivity, with five tests having a sensitivity below 65%. In participants with suspected COVID-19 infection, the rapid tests had very low sensitivities. Most rapid tests were easy to perform and interpret. Conclusions: Rapid tests were not suited as stand-alone tests to detect present infection in a Norwegian primary care emergency room population. All the rapid tests were able to detect SARS-CoV-2 antibodies, although sensitivities varied and were generally higher in the study arm of more severely affected participants. Rapid tests with high IgG sensitivity (and specificity) may be useful for confirmation of past infection. An independent evaluation should be performed in the intended population before introducing a rapid test.