Validation/Verification of Abbott RealTime SARS-CoV-2 Assay on the Abbott m2000 System: The Veteran Affairs Medical Center (VAMC) Experience

Abstract

Introduction/Objective The extraordinary circumstances of the highly contagiousSARS-CoV-2 pandemic have led the FDA to approve diagnosticassays with emergency use authorizations (EUA). One of theseassays is the Abbott RealTime SARS-CoV-2 assay (Abbott Park, Ill.). However, the literature is sparse on the validation of EUAassays for SARS-CoV-2 assays for this crisis; therefore, wepresent the Veteran Affairs Medical Center (VAMC) experiencein validating/verifying this test for clinical use. Methods Validation/verification was performed in three parts as part of quality assurance/quality improvement; 1) sample/patientcorrelation, 2) precision, and 3) validation/verification of accuracy at the lower limit of detection (LOD). The results from these studies was compiled, reviewed by the laboratory, and after performance was deemed satisfactory, the test would beput for clinical use. Results For the sample/patient correlation, a total of 68 known positive and 59 known negative samples were run; these included 56positive contrived samples or controls, 12 known positivepatient samples, 31 negative contrived or controls, and 28 known negative patient samples. All results from the assay were as expected with 100% positive and negative percent agreementexcept for one sample that was quantity not sufficient fortesting. The precision study with 4 known positive and 4 knownnegative samples run once per day for 5 days yielded perfect100% precision for both the positive and negative samples.Replicates to determine accuracy at the lower LOD (100 viruscopies/ml per instructions for use of the assay) demonstratedaccuracy even with dilutions down to 50 virus copies/ml. For this third step, 3 replicates each had been performed at 1000,500, 250, 70, 60 and 50 virus copies/ml. As 100 virus copies/ml was the provided manufacturer LOD, 7 replicates were performed at 100 virus copies/ml. Conclusion The validation/verification indicated that the Abbott RealTimeSARS-CoV-2 assay performed with expectations including with real patient samples and could be put into clinical use at theVAMC. After this validation/verification, the assay has been verysuccessfully used for in-house testing for SARS-CoV-2. In fact, the validation demonstrated an LOD as low as 50 viruscopies/ml, suggesting the assay may be even more sensitive tolow levels of viremia than is stated in the EUA.