Field Evaluation of a Duplex RT-RAA Assay for Rapid Detection of SARS-CoV-2 - Hebei Province, China, January 2021

Abstract

Introduction: Recently, a local cluster epidemic has occurred in Shijiazhuang City, Hebei Province. Failure to promptly identify patients with fever in rural areas was the major reason for this epidemic.

Methods: We presented the field evaluation of a new real-time reverse transcription recombinase-aided amplification (RT-RAA) kit incorporating an endogenous internal control in a single-tube format, completed at the Hebei CDC from January 17, 2021 to January 27, 2021.

Results: We evaluated the diagnostic performance of RT-RAA assay using automatic extracted RNA of 808 clinical samples. Compared with reverse transcriptase real-time quantitative PCR (qRT-PCR), RT-RAA kit achieved 92.41% sensitivity, 98.78% specificity and a 96.29% coincidence rate, demonstrating an excellent agreement between the RT-RAA assay and qRT-PCR assay. Furthermore, 58 samples were extracted using a manual extraction method within 5 minutes, but only samples with high nucleic acid concentration (cycle threshold value not higher than 32) could be stably detected.

Discussion: The RT-RAA is more suitable to meet the needs of rapid, sensitive, and accurate detection in community-level medical institutions.

Keywords: COVID-19; RT-RAA kit; SARS-CoV-2; the field evaluation.

Figure 1

Schematic diagram of the endogenous internal controlled RT-RAA assay for detection of SARS-CoV-2.

Figure 2

Sensitivity of the duplex RT-RAA assays for SARS-CoV-2 RNA using diluted National Reference (S1–S6).

Figure 3

Scatter diagram analysis of RT-RAA threshold time (TT) (y-axis) and qRT-PCR cycle threshold values (Ct) (x-axis).