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Comparative Evaluation of Two Automated Multiplex RT-PCR Tests for Rapid Detection of Influenza and Respiratory Syncytial Viruses by Kyu-Hwa Hur, Heungsup Sung, Mi-Na Kim

Background: Rapid and accurate diagnosis of influenza virus (Flu) and respiratory syncytial virus (RSV) is important for managing both the patient and laboratory. We compared the cobas Influenza A/B & RSV assay (cobas Liat) with the Simplexa Flu A/B & RSV assay (Simplexa) to evaluate which test method is more advantageous considering the resources of the laboratory and results of test performance.
Methods: A total of 236 respiratory specimens from patients referred for respiratory virus testing were retrospectively evaluated; 53 specimens tested positive for each of Flu A, Flu B, and RSV, and 77 specimens tested negative based on the results of the reference method, i.e., the Seegene Allplex Respiratory Panel 1/2/3 (Seegene, Seoul, Korea). The turnaround time (TAT) was 20 minutes per specimen for cobas Liat and 78 minutes per eight speci-mens for Simplexa. The total hands-on time was around one minute per specimen for both tests. The specimen volume required for testing was 200 µL for cobas Liat and 50 µL for Simplexa. Seegene Allplex Respiratory Panel 1/2/3 was used as the reference method.
Results: The number of invalid results was 1 (0.4%) for cobas Liat and 10 (4.2%) for Simplexa (p < 0.05). All results were consistent with those of the reference method in cobas Liat. The sensitivity and specificity for Flu A, Flu B, and RSVA were 100% with Simplexa. However, the sensitivity for RSVB was 80.0% with Simplexa, which was a statistically significant difference with the finding for cobas Liat (p < 0.05). Comparison of the cycle threshold (Ct) values of RSV for Simplexa with the reference method showed correlation as continuous variables (p < 0.001) with a higher propensity for obtaining Ct values with Simplexa, the exception being the six false negative results; their Ct values were more than 30 in the reference method.
Conclusions: Cobas Liat showed accurate performance with a rapid TAT and a good workflow efficiency. Cobas Liat is more efficient than Simplexa as a point-of-care test for the detection of RSV.

DOI: 10.7754/Clin.Lab.2020.201024