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

Abstract

Introduction/ObjectiveThe extraordinary circumstances of the highly contagious SARS-CoV-2 pandemic have led the FDA to approve diagnostic assays with emergency use authorizations (EUA). One of these assays is the Abbott RealTime SARS-CoV-2 assay (Abbott Park, Ill.). However, the literature is sparse on the validation of EUA assays for SARS-CoV-2 assays for this crisis; therefore, we present the Veteran Affairs Medical Center (VAMC) experience in validating/verifying this test for clinical use.MethodsValidation/verification was performed in three parts as part of quality assurance/quality improvement; 1) sample/patient correlation, 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 be put for clinical use.ResultsFor the sample/patient correlation, a total of 68 known positive and 59 known negative samples were run; these included 56 positive contrived samples or controls, 12 known positive patient 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 agreement except for one sample that was quantity not sufficient for testing. The precision study with 4 known positive and 4 known negative samples run once per day for 5 days yielded perfect 100% precision for both the positive and negative samples. Replicates to determine accuracy at the lower LOD (100 virus copies/ml per instructions for use of the assay) demonstrated accuracy 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.ConclusionThe validation/verification indicated that the Abbott RealTime SARS-CoV-2 assay performed with expectations including with real patient samples and could be put into clinical use at the VAMC. After this validation/verification, the assay has been very successfully used for in-house testing for SARS-CoV-2. In fact, the validation demonstrated an LOD as low as 50 virus copies/ml, suggesting the assay may be even more sensitive to low levels of viremia than is stated in the EUA.